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EXECUTIVE COMMITTEE

President Glen W. Yeager

Holly Sugar Corporation Colorado Springs, Colorado Vice President M. A. Woods

Union Sugar Division Santa Maria, California

Secretary Treasurer James H. Fischer Beet Sugar Development Foundation Fort Collins, Colorado Immediate Past President Hugh G. Rounds

The Amalgamated Sugar Company Ogden, Utah

B O A R D O F D I R E C T O R S

Pacific Coast Region: Sam C. Campbell

Intermountain Region: M. Keith Ellis

Eastern Rocky Mountain Region: John A. Worrall

North Central and Great Lakes Region: Alan Dexter

Canada: Stanley George Processing at Large: J. A. E. Rich Agriculture at Large: Stewart Bass

Manuscript submitted for publication and communication pertaining to editorial matters should be sent to James H. Fisher, Secretary-Tresurer, American Society of Sugar Beet Technologists, P. O. Box 1546, Fort Collins, Colorado 80522. Each manuscript received for publication will be appraised for its technical and historical value by a Publications Committee. The Publications Committee shall have final authority regarding publication of manuscripts. The Journal of the American Society of Sugar Beet Technologists shall contain papers presented at General and Regional meetings and articles of immediate interest prepared specifically for this periodical.

JOURNAL of the

American Society of Sugar Beet Technologists

Volume 19 Number 2

October 1976

Published semi-annually by

American Society of Sugar Beet Technologists

Office of the Secretary

P.O. Box 1546

Fort Collins, Colorado 80522

Subscription prices:

$4.50 per year, domestic $5.00 per year, foreign $2.50 per copy, domestic $2.80 per copy, foreign

Made in the United States of America

TABLE OF CONTENTS Title Author Page

Effect of Drying Temperature and F. W. Snyder Fruit Moisture on Germination of Richard J. Patterson Sugarbeet Seed Paul Bergdolt 101

E. G. Ruppell Benomyl-Tolerant Strains of L. M. Burtch

Cercospora Beticola from Arizona A. D. Jenkins 106

The Effect of Aldicarb on Growth of R. E. Peckenpaugh

Sugarbeet C. C. Blickenstaff 108

Sticky Stake Traps for Monitoring Fly Populations of the Sugarbeet Root Maggot and Predicting Maggot C. C. Blickenstaff Populations and Damage Ratings R. E. Peckenpaugh 112

Soil Nitrate and the Response of F.J. Hills Sugarbeets to Fertilizer Nitrogen Albert Ulrich 118

Competition of Annual Weeds and Steven R. Winter

Sugarbeets Allen F. Wiese 125

Effect of Crown Material on Yield and Quality of Sugarbeet Roots: A Grower D. F. Cole Survey G. F. Seiler 130

A Revised Method for Determining G. E. Varvel Phosphate-Phosphorus Levels in G. A. Peterson Sugarbeet Leaf Petioles F. N. Anderson 138

Effects of Weather Variables on the Yields of Sugarbeets Grown in an Irrigated S. Dubetz

Rotation for Fifty Years M. Oosterveld 143

Tests with Fungicides to C. L. Schneider Control Rhizoctonia Crown H. S. Potter Rot of Sugarbeet D. L. Reichard 150

Effect of Fungus Infection on Respiration and Reducing Sugar Accumulation of Sugarbeet Roots and Use of D. E. Mumford Fungicides to Reduce Infection R. E. Wyse 157

Sugarbeet Yield and Theoretical Photosynthesis in the Northern Great Plains E.J. Doering 162

Effect of Drying Temperature and Fruit Moisture on Germination of Sugarbeet Seed1

F. W. SNYDER, R I C H A R D J . P A T T E R S O N , and PAUL B E R G D O L T 2

Received for publication March 17, 1975

Occasional ly , s u g a r b e e t seed m u s t be h a r v e s t e d b e f o r e i t is fully m a t u r e a n d m a d e avai lable for i m m e d i a t e use . T h u s , o n e n e e d s t o know t h e a p p r o x i m a t e s tage o f m a t u r i t y , t he m o i s t u r e c o n t e n t , a n d t h e t e m p e r a t u r e a t which t h e seed can be r ap id ly a n d safely d r i e d w i t h o u t i m p a i r i n g g e r m i n a t i o n .

R e s e a r c h d u r i n g the last d e c a d e has a i d e d in c lar i fying the relat i onsh ips b e t w e e n frui t m o i s t u r e a t ha rves t , seed m a t u r i t y , a n d g e r m i na t ion o f s u g a r b e e t seed ( 2 , 3 , 4).3 We r e p o r t t h e effect on g e r m i n a t i o n of e x p o s i n g frui ts h a r v e s t e d a t va r ious m o i s t u r e c o n t e n t s to d i f f e r en t d r y i n g t e m p e r a t u r e s . Also, w e suggest d r y i n g t e m p e r a t u r e s t h a t d o not affect g e r m i n a t i o n adverse ly .

M e t h o d s and Materials

Frui ts of s u g a r b e e t (Beta vulgaris L.) w e r e h a r v e s t e d at va r ious stages o f m a t u r i t y f r o m ind iv idua l p lan t s o f cul t ivars g r o w n in t h e f i e ld o r in t h e g r e e n h o u s e . S a m p l e s o f t h e freshly h a r v e s t e d frui ts w e r e d r i e d in a fo rced-a i r d r y e r a t t e m p e r a t u r e s not e x c e e d i n g 65.6° C. Fru i t s to be d r i e d w e r e p laced as a s ingle layer in w i r e - m e s h baske t s (6 x 6 in.) . F o u r baskets were p laced vertically a few inches a p a r t . Air at a re la t ive h u m i d i t y of 6 to 11% a n d a velocity of 3.7 ft sec 1 was used for d r y i n g t h e frui ts . Air t e m p e r a t u r e was m e a s u r e d j u s t b e f o r e t he air passed a r o u n d t h e frui ts in t h e f i r s t baske t . Ca lcu la t ions i nd i ca t ed t h a t t h e relat ive h u m i d i t y o f t h e ef f luent a i r was n o t c h a n g e d a p p r e c i a b l y by t h e quan t i t y o f w a t e r r e m o v e d f r o m t h e frui ts d u r i n g d r y i n g . The forced-a i r d r y i n g t e m p e r a t u r e s w e r e m a i n t a i n e d for 3 h o u r s . Since some s a m p l e s d i d n o t a t ta in a i r -d ry e q u i l i b r i u m in t h e 3 h o u r s whi le o t h e r s w e r e s o m e w h a t d r i e r , all s a m p l e s w e r e r e t u r n e d t o t h e l abor tory to a t ta in a i r -d ry e q u i l i b r i u m b e f o r e use in g e r m i n a t i o n tests. Samples of fruits f rom s o m e p l an t s also w e r e p laced d i rec t ly in t h e labortory to equ i l ib ra t e slowly with t h e air . We o v e n - d r i e d a small p o r t i o n of each s a m p l e of frui ts a t 100°C, to ob ta in d r y we igh t s for ca lcu la t ion of

1Cooperative investigations of the Agricultural Research Service, U.S. Department of Agriculture, and the Michigan Agricultural Experiment Station. Approved for publication as Journal Article 6674, Michigan Agricultural Experiment Station.

2Plant Physiologist, Agricultural Research Service, U.S. Department of Agriculture, P.O. Box 1633, East Lansing, Michigan 48823; instructor; and former Graduate Assistant, Agricultural Engineering Department, Michigan Slate University, East Lansing, Michigan 48824, respectively.

3Numbers in parentheses refer to literature cited.

102 JOURNAL OF THE A.S.S.B.T.

moisture contents. All moisture percentages are expressed on the basis of the oven-dry weight of the fruits. The limited quantity of seeds from an individual plant precluded drying a sample at each temperature.

After fruits attained air-dried equilibrium, the corky material was removed from the fruits by hand rubbing. Seedlots were identified by plant number and drying temperature. At least 90 seeds were germinated for 7 days on blotters in a germinator at about 21° C. Germination percentages of the seeds dried at elevated temperatures were compared with those dried at the lower temperatures for indications of heat injury during drying. Corrections were made for fruits containing no seed and those containing seeds judged not to be developed enough to germinate.

Simple and partial correlations were calculated. The data also were used in two simple regression models in our attempt to confirm the relation between fruit moisture and safe drying temperatures derived by inspection of the germination data.

Results At a given drying temperature, the degree of heat injury, as mea

sured by germination percentage, generally was inversely related to fruit moisture (Table 1). Simple correlations (rs) and partial correlations ( r p ) were calculated. Germination percentage and fruit

Table 1.—Effect of drying sugarbeet fruits of different moisture contents at given temperatures on blotter germination.

1Moisture percentages on basis of fruit dry weight.

VOL. 19, No. 2, OCTOBER 1976 103

m o i s t u r e co r r e l a t ed , r s = —0.530**, r p = —0.688**. G e r m i n a t i o n p e r c e n t a g e a n d d r y i n g t e m p e r a t u r e c o r r e l a t e d , r s = —0.468**, r p = — 0.655**. A l inear a n d a q u a d r a t i c r eg res s ion m o d e l failed to re la te fruit m o i s t u r e a n d d r y i n g t e m p e r a t u r e t o t h e p e r c e n t a g e o f g e r m i n a t ion, p robab ly because t he p e r c e n t a g e dec rea se s prec ip i tous ly w h e n t h e d r y i n g t e m p e r a t u r e exceeds t he critical t h r e s h o l d .

At fruit m o i s t u r e c o n t e n t s o f 6 3 % or less (d ry-weigh t basis), d r y i n g t e m p e r a t u r e s up to 65.6° C d id n o t d e p r e s s b lo t t e r g e r m i n a t i o n . Between 63 a n d 2 3 0 % fruit m o i s t u r e , d r y i n g t e m p e r a t u r e s o f 60° C or lower caused relatively little injury. F ru i t s h a r v e s t e d with m o r e t h a n 230% m o i s t u r e w e r e in ju red a t d r y i n g t e m p e r a t u r e s of 54.4° C or h i g h e r (Tab l e 1). T h e d a t a sugges t a p l a n t - b y - d r y i n g - t e m p e r a t u r e in te rac t ion , t h a t seed samples f r o m d i f f e r en t p l an t s d i f f e red in sensitivity to h e a t in jury , a n d tha t this sensitivity does no t s eem to be re la ted solely to f ru i t -mo i s tu re c o n t e n t . Fo r e x a m p l e , seeds o f p l an t n o . 10 (Tab le 1) a t 140% frui t m o i s t u r e a n d p l an t n o . 16 at 2 3 0 % m o i s t u r e b o t h g e r m i n a t e d in excess o f 9 5 % w h e n they w e r e d r i e d a t 60° C. H o w e v e r , w h e n they w e r e d r i e d a t 65.6° C , 3% o f t h e seeds o f p l an t n o . 10 a n d 3 8 % of t h e seeds of p l an t n o . 16 g e r m i n a t e d .

After 3 h o u r s u n d e r o u r forced-a i r d r y i n g c o n d t i o n s , fruits h a v i n g an initial m o i s t u r e of 2 3 0 % or m o r e a n d d r i e d a t 37.8° C d id no t d r y e n o u g h for safe s to rage . In con t ra s t , f rui ts h a v i n g an initial m o i s t u r e of 2 9 0 % a n d d r i e d a t 48.9° C t h e n h a d less t h a n 2 0 % m o i s t u r e . Fru i t s h a v i n g an initial m o i s t u r e of 3 3 0 % a n d d r i e d a t 60° C t h e n h a d less t h a n 10% m o i s t u r e .

Since no t e m p e r a t u r e gu ide l ines exist for fo rced-a i r d r y i n g o f freshly h a r v e s t e d s u g a r b e e t seeds , t h e t e m p e r a t u r e s in F i g u r e 1 a r e sugges t ed as safe l imits. T h e s e t e m p e r a t u r e s a r e a b o u t 2.8° C lower t h a n d r y i n g t e m p e r a t u r e s t h a t a p p e a r e d t o cause n o d e p r e s s i o n i n b lo t te r g e r m i n a t i o n .

Figure 1.—Suggested safe dry ing temperature for freshly harvested sugarbeet seeds.


D i s c u s s i o n

I f d r y i n g e q u i p m e n t s imilar to that used in this s tudy were available, t he a p p r o x i m a t e fruit m o i s t u r e of a s u b s a m p l e cou ld be de t e r m i n e d in 3 h o u r s . A safe d r y i n g t e m p e r a t u r e could t h e n be selected for d r y i n g the seed s amp le . W i t h o u t such e q u i p m e n t , a relatively slow d r y i n g ra te would be p r e f e r a b l e to r i sk ing injury to t he seed.

E v a p o r a t i v e cool ing d u r i n g t h e d r y i n g process can m a i n t a i n t h e t e m p e r a t u r e o f t h e seed below the critical t e m p e r a t u r e tha t causes injury. Since 3 h o u r s of d r y i n g at 54.4 to 60.0° C r e d u c e d fruit m o i s t u r e c o n t e n t to less t h a n 1 5 %, evapora t ive cool ing d u r i n g t h e la t te r p a r t o f d r y i n g m u s t have b e e n min ima l . T h u s , w e believe tha t t h e t e m p e r a t u r e o f t h e seed closely a p p r o x i m a t e d the s u r r o u n d i n g air t e m p e r a t u r e a n d tha t the ind ica ted d r y i n g t e m p e r a t u r e essentially fully affected la ter g e r m i n a t i o n . T h e resul t s o f H a r r i s o n a n d W r i g h t (1) i n d r y i n g ea r s o f seed c o r n sugges t t ha t evapora t ive coo l ing d u r i n g t h e ear ly pa r t o f t h e d r y i n g o p e r a t i o n can actually min imize d a m a g e , w h e r e a s l o n g e r d ry ing may m a r k e d l y d e p r e s s g e r m i n a t i o n .

Ce r t a in gu ide l ines may aid in e s t ima t ing fruit m o i s t u r e a n d sensitivity o f t h e seed to hea t w h e n e q u i p m e n t a n d sufficient t ime a r e no t available for p r e l im ina ry d ry ing . F ru i t s of ind iv idua l s u g a r b e e t p lan ts ha rves t ed 40 days af ter first b l o o m r a n g e d in m o i s t u r e f rom 145 to 2 5 9 % (on basis of d ry frui t weight) (2). Seeds f rom these p lan ts , af ter air d r y i n g a n d h a n d process ing , g e r m i n a t e d f rom 40 to 100% on b lo t te rs in 10 days . Since g e r m i n a t i o n p e r c e n t a g e s a re inversely c o r r e lated with fruit m o i s t u r e (2), t he g e r m i n a t i o n p e r c e n t a g e of a po r t ion of t h e seeds t h a t a r e d r i e d a t l abo ra to ry air t e m p e r a t u r e or a t 37.8° C m u s t be used to d e t e r m i n e w h e t h e r d r y i n g a t h i g h e r t e m p e r a t u r e s i s d e t r i m e n t a l .

Seeds of p lan t n o . 4 (25% fruit m o i s t u r e at harves t ) a n d p lan t n o . 8 (45%) g e r m i n a t e d 96 a n d 97% af ter 3 h o u r s of d r y i n g a t 57.2° C, b u t g e r m i n a t e d only 40 a n d 6 2 % af te r 3 h o u r s d r y i n g a t 37 .8°C ( T a b l e 1). T h e s e l a rge d i f fe rences in g e r m i n a t i o n c a n n o t r easonab ly be a t t r i b u t e d t o c h a n c e , since t he seeds w e r e h a r v e s t e d a n d tes ted on an ind iv idua l -p lan t basis. In ear l ie r s tudies , seedlots subjec ted to m o d e r ately e levated t e m p e r a t u r e s for a p e r i o d of t ime also h a d cons ide rab ly h i g h e r g e r m i n a t i o n t h a n s u b s a m p l e s e x p o s e d t o t e m p e r a t u r e s betw e e n 0 a n d 40° C. In con t ras t , seeds of p lan t n o . 5 with 26%; a n d of p l an t n o . 7 with 4 0 % m o i s t u r e a t ha rves t d i d not r e s p o n d to m o d e r a t e l y h i g h d r y i n g t e m p e r a t u r e , b u t they h a d equal ly h igh g e r m i n a t i o n a t a i r t e m p e r a t u r e a n d a t 57.2° C ( T a b l e 1). We do n o t k n o w wha t m e c h a n i sm s t imula tes g e r m i n a t i o n o f ce r t a in freshly h a r v e s t e d seeds af te r e x p o s u r e to m o d e r a t e l y e levated t e m p e r a t u r e s for a p e r i o d of t ime .

In this s tudy , d r y i n g - t e m p e r a t u r e injury was d e t e c t e d solely by b l o t t e r - g e r m i n a t i o n da ta . In a r ecen t s tudy , t h e p e r f o r m a n c e of seedlots ha rves t ed ove r a r a n g e of ma tu r i t i e s was c o m p a r e d by b lo t t e r g e r m i n a t i o n a n d by e m e r g e n c e t h r o u g h 1.5 in. of f ine , mois t s a n d (3). T h e s e da t a clearly s h o w e d t h a t t h e b l o t t e r - g e r m i n a t i o n test was less

VOL. 19, No. 2, OCTOBER 1976 105

able to de tec t t he a d v e r s e effects (e.g. , lack of vigor) of seed i m m a t u r i t y t h a n the s a n d - e m e r g e n c e test. T h u s , h a d t h e s a n d - e m e r g e n c e test been available for this d r y i n g - t e m p e r a t u r e s tudy , s o m e w h a t d i f fe ren t injury levels migh t h a v e b e e n revea led .

S u m m a r y S u g a r b e e t frui ts w e r e h a r v e s t e d over a r a n g e of frui t m o i s t u r e

c o n t e n t s a n d t h e n d r i e d at d i f fe ren t t e m p e r a t u r e s in air of 6 to 1 1 % relat ive h u m i d i t y a n d a velocity of 3.7 ft s e c - 1 . B lo t t e r g e r m i n a t i o n was used to de tec t in jury to t h e seed.

Seed s a m p l e s f rom d i f fe ren t p l an t s d i f fe red in the i r sensitivity to hea t injury. T h e sensitivity was no t consis tent ly re la ted to t h e fruit m o i s t u r e , b u t h e a t in jury a t a g iven t e m p e r a t u r e was inversely re la ted to fruit m o i s t u r e . A safe d r y i n g t e m p e r a t u r e has been sugges t ed for a r a n g e of frui t m o i s t u r e s a t ha rves t .

A c k n o w l e d g m e n t We a p p r e c i a t e t h e aid o f C h a r l e s Cress , C r o p a n d Soil Sciences

D e p a r t m e n t , Mich igan Sta te Univers i ty , for t h e statistical analyses a n d i n t e r p r e t a t i o n .

Literature Cited (1) HARRISON, C M. and A. H. WRIGHT. 1929. Seed corn drying experi

ments. J. Am. Soc. Agron. 21: 994-1000. (2) SNYDER, F. W. 1971. Relation of sugarbeet germination to maturity and

fruit moisture at harvest. J. Am. Sugar Beet Technol. 16: 541-551. (3) SNYDER, F. W. 1974. Maturity effects on fruit characteristics, germina

tion, and emergence of sugarbeet. J. Am. Soc. Sugar Beet Technol. 18: 87-95.

(4) T E K R O N Y , D. M. 1969. Seed deve lopmen t and germina t ion of monogerm sugar beets (Beta vulgaris L.) as affected bv maturity. Ph.D. Thesis, Oregon Stale University. 120 p.

Benomyl-Tolerant Strains of Cercospora beticola from Arizona1

E. G. R U P P E L , L. M. B U R T C H , a n d A. D. J E N K I N S 2

Received for publication June 2, 1976

Stra ins of t h e s u g a r b e e t (Beta vulgaris L.) leaf spot f u n g u s (Cercospora beticola Sacc.) t o l e r a n t to m e t h y l l - (buty lcarbamoly l-2-benzimic lazo lecarbamate ( b e n o m y l ) h a v e b e e n r e p o r t e d f r o m G r e e c e ( l ) 3

a n d t h e p a n h a n d l e r e g i o n o f T e x a s (4). A l t h o u g h i t was r e c o m m e n d e d t h a t t h e use o f o n e selective fungic ide o n large a c r e a g e s s h o u l d b e d i s c o u r a g e d (4), m o s t g r o w e r s h a v e c o n t i n u e d a l m o s t exclusive use of b e n z i m i d a z o l e s w h e r e leaf spot i s e p i d e m i c .

D i m i n i s h e d effectiveness o f b e n o m y l for c o n t r o l l i n g leaf spot was o b s e r v e d in s u g a r b e e t f ie lds n e a r Willcox, Ar izona, in 1974, a n d in a fung ic ide t r i a l n e a r VVillcox in 1975. C o n s e q u e n t l y , tests w e r e c o n d u c t e d t o d e t e r m i n e i f b e n o m y l - t o l e r a n t s t ra ins w e r e p r e s e n t .

C e r c o s p o r a - i n f e c t e d leaf s a m p l e s w e r e col lected f r o m s u g a r b e e t plots t h a t h a d b e e n s p r a y e d with b e n o m y l o r t r i p h e n y l t i n h y d r o x i d e , a n d f r o m n o n t r e a t e d c o n t r o l p lots . S a m p l e s w e r e d r i e d a t r o o m t e m p e r a t u r e , c r u s h e d , a n d u s e d t o i n o c u l a t e s u g a r b e e t s i n t h e g r e e n h o u s e . W h e n leaf spots d e v e l o p e d , s p o r u l a t i o n was i n d u c e d b y p lac ing t h e p l a n t s in a h u m i d i t y c h a m b e r . Single s p o r e isolat ions (30 p e r s a m p l e ) w e r e m a d e a s previous ly d e s c r i b e d (2), a n d t h e r e s u l t a n t c u l t u r e s w e r e p l a t e d on p o t a t o - d e x t r o s e a g a r (PDA) c o n t a i n i n g 5 μg active i n g r e d i e n t (a.i.) b e n o m y l / m l . A k n o w n benomyl-sens i t ive isolate of C. beticola ( C - l ; A T C C 24078) f r o m C o l o r a d o was i n c l u d e d in all p lates as a c o n t r o l . In this test, all isolates f r o m A r i z o n a grew profuse ly on b e n o m y l - a m e n d e d PDA, w h e r e a s isolate C-l was c o m p l e t e l y i n h i b i t e d .

In a s e c o n d test, 20 r a n d o m l y se lected s ing le-spore isolates f r o m c u l t u r e s d e s c r i b e d above a n d isolate C-l w e r e p l a t e d o n P D A cont a i n i n g 0, 1, 10, 100, 1,000 μg a.i. b e n o m y l / m l . M e a s u r e m e n t s of l inear g r o w t h a f te r 7 days i n c u b a t i o n at 25°C r e v e a l e d t h a t t h e

1Cooperative investigations of the Agricultural Research Service, U.S. Department of Agriculture; Spreckels Sugar Division, Amstar Corporation; the Colorado State University Experiment Station; and the Beet Sugar Development Foundation. Published with approval of the Director, Colorado State University Experiment Station, as Scientific Series Paper No. 2124.

2Research Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, Crops Research Laboratory, Colorado State University, Fort Collins, Colorado 80523; Chief Agronomist and Agronomist, Spreckels Sugar Division, Amstar Corporation, Mendota, California 93640 and Chandler, Arizona 85224, respectively.


VOL. 19. No. 2, OCTOBER 1976 107

A r i z o n a isolates h a d var ied d e g r e e s o f b e n o m y l t o l e r a n c e s imi lar to t h o s e isolates f r o m s u g a r b e e t s g r o w n i n T e x a s (3). T h e E D 5 0 (conc e n t r a t i o n o f b e n o m y l c a u s i n g 5 0 % g r o w t h inhib i t ion) o f n i n e isolates was b e t w e e n 100 a n d 1,000 μg/ml, w h e r e a s f o u r isolates h a d a n E D 5 0

of 100 μg/ml. Six isolates h a d an E D 5 0 b e t w e e n 10 a n d 100, a n d only o n e i s o l a t e h a d a n E D 5 0 o f 1 0 μg/ml. Isolate C-l grew only o n t h e b e n o m y l - f r e e m e d i u m . No isolate was a s t o l e r a n t a s H I - 1 2 ( E D 5 0 = b e t w e e n 1,000 a n d 5,000 μg/ml) f r o m T e x a s (3).

A l t e r n a t i n g b e n z i m i d a z o l e a n d p r o t e c t a n t - t y p e fungic ides has n o t p r o v i d e d a d e q u a t e c o n t r o l o f s u g a r b e e t leaf spot in T e x a s (E. G. R u p p e l , personal observation). T h u s , we r e c o m m e n d t h a t t h e use of b e n z i m i d a z o l e s b e d i s c o n t i n u e d i n a r e a s w h e r e b e n o m y l - t o l e r a n t s t ra ins a r e f o u n d . T h e use o f o t h e r fungic ides, s u c h a s t r i p h e n y l t i n h y d r o x i d e (5), a n d g r o w i n g s u g a r b e e t cult ivars re s i s tant to C. beticola s h o u l d effectively c o n t r o l t h e disease.

Literature Cited

(1) GEORGOPOULOS, S. G. and C. DOVAS. 1973. A serious outbreak of strains of Cercospora beticola resistant to benzimidazole fungicides in northern Greece. Plant Dis. Reptr. 57: 321-324.

(2) RUPPEL, E. G. 1972. Variation among isolates of Cercospora beticola from sugar beet. Phytopathology 62: 134-136.

(3) RUPPEL, E. G. 1975. Biology of benomyl-tolerant strains of Cercospora beticola from sugar beet. Phytopathology 65: 785-789.

(4) RUPPEL, E. G. and P. R. SCOTT. 1974. Strains of Cercospora beticola resistant to benomyl in the U.S.A. Plant Dis. Reptr. 58: 434-436.

(5) SCHNEIDER, C. L., H. S. POTTER, and F. B. RUSSELL. 1971. Gontrol of Cercospora leaf spot of sugarbeet through aerial application of systemic and surface-protecting fungicides. J. Am. Soc. Sugar Beet Technol. 16: 525-529.

The Effect of Aldicarb On Growth of Sugarbeets

R . K . P E C K E N P A U G H a n d C . C . B L I C K E N S T A F F 1

Received for publication February 26, 1976

Introduct ion In o u r field tests with t he systemic insect icide a ld ica rb for con t ro l

of t h e suga rbee t roo t m a g g o t , Tetanops myopaeformis (Rode r ) , the p lants in t r ea t ed plots have of ten p r o d u c e d m o r e d e n s e t o p g r o w t h t han those in u n t r e a t e d plots , even in t he absence of d a m a g i n g p o p u l a t i o n s of root m a g g o t s or o t h e r obvious insect d a m a g e . H o w e v e r , a ld icarb i s regist e r ed for the con t ro l of a variety of insects, mites , a n d n e m a t o d e s . It is possible tha t con t ro l of these pests , each a t seemingly n o n - e c o n o m i c levels, leads to the i m p r o v e d p l an t p e r f o r m a n c e . But t h e r e is speculation tha t a l d i c a r b d i rec t ly s t i m u l a t e s p l a n t g r o w t h ( 1 , 2 , 3 , 5) .2

G r e e n h o u s e tests w e r e t h e r e f o r e c o n d u c t e d t o d e t e r m i n e w h e t h e r a ld icarb itself s t imu la t ed suga rbee t g r o w t h .

Materials and Methods In t he win te r of 1973-74, P o r t n e u f silt loam from a single he ld was

p r e p a r e d 3 ways: u n t r e a t e d , hea t - s te r i l i zed , a n d f u m i g a t e d with e t h y l e n e d i b r o m i d e . The soil was placed in 6 in. pots a n d each po t was p l a n t e d with 4 seeds of a suga rbee t single cross hybr id . T h e n a ld icarb 10G was app l i ed at t he t ime of s e e d i n g at ra tes of 1, 2, a n d 4 lb. AI / ac re (as c o n c e n t r a t e d in a 5 1/2 in. b a n d on 22 in. rows above the seed) a n d w a t e r e d in with 8 oz. wa te r /po t . Pots with no a ld ica rb were i nc luded as checks . All t r e a t m e n t s were r a n d o m i z e d wi thin 4 repl icates . Seed l ings were t h i n n e d to o n e p lan t /po t . All p lan t s rece ived the s a m e a m o u n t o f wate r w h e n a t least hal f t he pots w e r e d r y . T h e d a t a t a k e n 71 days af ter the seedl ings e m e r g e d w e r e : leaf l eng th , leaf weight (air dry) , n u m b e r of leaves, roo t weight , root l eng th , a n d roo t d i a m e t e r .

T h e second test, c o n d u c t e d d u r i n g t h e win te r o f 1974-75, d i f fe red s o m e w h a t . In J a n u a r y , a p p r o x i m a t e l y 225 s ingle cross beet seeds were p l a n t e d in a ha t . T h r e e weeks af ter e m e r g e n c e , 75 seed l ings in t h e co ty ledon or 2-leaf stage were t r a n s p l a n t e d in to 6 in. clay pots filled with a g r e e n h o u s e soil m i x t u r e of 2 pa r t s d a r k soil, 2 pa r t s l ight soil, 3/1 p a r t cow m a n u r e , a n d 1/5 p a r t s and . Ald ica rb was app l i ed 10 days af te r t r a n s p l a n t i n g by s p r i n k l i n g it on t he soil sur face at ra tes of 1/2 , 1, a n d 2 lb. AI /ac re b a n d e d on 22 in. rows (this is equ iva len t to b roadcas t ra tes

1Agricultural Research Technician and Research Entomoiogist. respectively, ARS, USDA, Kimberly, Idaho 83341.


VOL. 19, N o . 2, OCTOBER 1976 109

of 2, 1, a n d 8 lb. A I/acre) (4) a n d t h e n sc ra t ch ing it in to t he soil to a d e p t h of 0.5 in. U n t r e a t e d pots were sc ra t ched in t he s a m e m a n n e r . All pots w e r e subsequen t ly given ident ical ca re excep t for w a t e r i n g : water ing was var ied so we could d e t e r m i n e w h e t h e r t he effect of a ld ica rb was d e p e n d e n t on t he a m o u n t of m o i s t u r e in the soil. T h u s 8, 6 , or 4 oz. of wa te r /po t was app l i ed to a g r o u p of po t s immedia te ly af ter the appl ication of a ld ica rb a n d t h e r e a f t e r w h e n at least half of the pots in a g r o u p were dry . All t r e a t m e n t c o m b i n a t i o n s were r a n d o m i z e d in 6 repl ica tes . Six weeks af ter t r e a t m e n t , the beets were r e m o v e d f rom the pots , t he soil was r e m o v e d f rom the roo ts by wash ing with a fine spray nozzle , a n d t h e t o p s w e r e cut off, m e a s u r e d , a n d left on tab les in t h e g r e e n h o u s e to air d ry . After 10 clays, t h e d r i e d tops were we ighed . Roots w e r e w e i g h e d a l t e r the t ops w e r e r e m o v e d a n d the root d i a m e t e r was r e c o r d e d a t t h e cu t t i ng po in t .

Resu l t s and C o n c l u s i o n s

In the 1973-74 test, only 38 of the or ig ina l p lants were ha rves t ed because of poor g e r m i n a t i o n a n d seed l ing mor ta l i ty . Also, the initial w a t e r i n g may have washed most of t h e a ld i ca rb out t h r o u g h t h e b o t t o m of the pot . In anv case t he soil in s o m e pots r e m a i n e d wet a n d mucky t h r o u g h o u t t he test. 1 he effect of soil s teri l izat ion c o m p a r e d with no steri l ization is r e p o r t e d in f ab le 1 as p e r c e n t a g e inc rease or dec rease in g r o w t h from that of the u n t r e a t e d plants for all ra tes of a ld icarb . H e a t steri l ization was a p p a r e n t l v d e t r i m e n t a l to g r o w t h , a n d E D B fumigat ion was beneficial . T h e effect of t h e ra tes of a ld i ca rb for all soil t r e a t m e n t s , also e x p r e s s e d as p e r c e n t a g e increase o r dec rea se from that of the u n t r e a t e d p lan ts , i s p r e s e n t e d in T a b l e 2 . Ald ica rb h a d no s t imula t ing effect on p lant g r o w t h a t any of the rates t es ted .

The resul ts o b t a i n e d in the 1974-75 test for t he ra tes of a ld icarb a r e shown in Table 3 in t e r m s of p e r c e n t a g e increase or d e c r e a s e f rom u n t r e a t e d checks . No c lear r e s p o n s e to close was d e m o n s t r a t e d for root

Table 1. — Effect of soil steri l ization on sugarbeet growth , 1973-74.

Table 2. — Effect of a ld icarb on sugarbeet growth, 1973-74.

110 JOURNAL OFTHE A.S.S.B.T.

weight , root d i a m e t e r , leaf l eng th , o r leal weight t h o u g h leaf weight was consis tent ly h i g h e r for a l d i ca rb - t r ea t ed p lan t s a n d s h o w e d an a v e r a g e of 6.44% increase . H o w e v e r , analyses of va r i ance of the s a m e m e a s u r e m e n t s for each r a t e of wa t e r showed significant d i f fe rences only for root we igh t a n d roo t d i a m e t e r w h e n the w a t e r r a t e was 6 oz. W h e n w a t e r ra tes w e r e c o m b i n e d i n an analysis o f v a r i a n c e , no significant d i f ferences w e r e o b t a i n e d .

Roo t a n d leaf weights , which m e a s u r e ac tua l vegeta t ive p r o d u c t ion, a r e p r e s e n t e d in T a b l e 4 . H e r e aga in , no significant r e s p o n s e to a ld ica rb was d e m o n s t r a t e d , bu t d i f fe rences d u e to w a t e r i n g ra tes a r e ev iden t . Also, co r r e l a t i ons be tween g r o w t h m e a s u r e m e n t s a n d ra tes o f app l ica t ion of a ld ica rb (Tab le 5) show tha t a ld ica rb h a d no significant effect excep t a nega t ive o n e on roo t weight a t t h e 4-oz. wa te r r a te . W a t e r ra tes w e r e posit ively a n d significantly c o r r e l a t e d wi th r o o t weight , leaf l eng th , a n d leaf weight . Leaf l eng th a n d roo t weight w e r e also significantly c o r r e l a t e d (r = 0.62**).

Any increase we o b t a i n e d in p l an t g r o w t h in o u r tests can only be a t t r i b u t e d to d i f fe rences in w a t e r i n g ra tes . T h u s increases in f ie ld yield a t harves t d u e to a ld ica rb p robab ly result only f rom t h e benefi ts of insect a n d / o r n e m a t o d e con t ro l . A ld ica rb i s an effective insect icide with systemic activity t ha t c o n t i n u e s for 2-3 m o n t h s , a n d m a n y insect pests inhabi t f ie lds . Indiv idual ly t he d a m a g e d u e to a pa r t i cu l a r

Table 3. — Effect of aldicarb on sugarbeet growth, 1974-75.

Table 4. — Root and top weight of sugarbeets associated with 3 rates of aldicarb and 3 rates of water. 1974-75.

1Values in ( ) art- the number of waierings. 2Differences in root weight among treatments for the 6-oz. water rate were significant at the

5% level.

VOL. 19, No. 2, OCTOBER 1976 111

Table 5. — The effect of aldicarb and water rates on sugarbeet leaf length, leaf weieht, and root weight as determined by correlation1 of data from 1974-75 test.

species may be very m i n o r , b u t w h e n they a r e a d d e d t o g e t h e r , t h e r e may be an e c o n o m i c loss. Such m i n o r d a m a g e cou ld go u n n o t i c e d by g r o w e r s o r f i e ldmen . I f a ld i ca rb s o m e t i m e s con t ro l s t hese m i n o r infesta t ions , t h e resul t w o u l d be i nc rea sed p l a n t g r o w t h a n d yield.

U n d e r t h e c o n d i t i o n s o f o u r tests, a ld i ca rb d e m o n s t r a t e d n o significant s t i m u l a t i n g effect on s u g a r b e e t s .

Literature Cited (1) ADAMS, R. G., Jr. , J. H. LILLY, and A. G. GENTILE. 1975. Effects of

certain systematic insecticides on gladiolus growth and spike production, j . Econ. Entomol. 68(5): 727-728.

(2) DUNNING, R. A. and G. H. WINDER. 1974. Effects of aldicarb and some other nematocides on growth of sugarbeet in Heterodera schachtii-infested soil. Plant Pathol. 23: 1-8.

(3) MuMFORD, D. L. and G. D. GRIFFIN. 1973. Evaluation of systemic pesticides in controlling sugarbeet leafhopper. J. Am. Soc. Sugar Beet Technol. 1 7(4):354-357.

(4) NEAL, J. W., J r . 1974. A manual for determining small dosage calculations of pesticides and conversion tables. Entomol. Soc. Am., College Park, Maryland. 72 pp.

(5) U N I O N CARBIDE CORPORATION. 1975. Temik® aldicarb pes t ic ide a systemic pesticide for control of insects, mites, and nematodes. Tech. Inf. Bookl., Agric. Prod. Serv., Salinas, California. 63 pp.

Sticky Stake Traps For Monitoring Fly Populations of the Sugarbeet Root Maggot

and Predicting Maggot Populations and Damage Ratings

C. C. BLICKENSTAFF and R. E. P E C K E N P A U G H 1

Received for publication February 26, 1976

Introduction Swensonand Peay (3)2 compared sticky stake traps of several colors

with 2 types of bait traps for monitoring populations of adult sugarbeet root maggots, Tetanops myopaeformis (Roder) (Diptera, Otitidae). From work done in 1965-67, they concluded that black and green colored stakes caught more flies than other colors and said that there was "a high correlation between numbers of flies trapped on sticky stakes and damage caused . . . " during those 3 years.

We report here additional work done during the period 1968-75 with traps of other colors, heights, and directions of exposure and the relationship between trap catches and subsequent maggot populations and damage ratings.

Procedure All comparisons of color utilized 1 x 12 in. garden stakes stuck in

the ground. These were colored with oil paints obtained locally. Painted stakes were matched with color charts (2) as follows:

In the comparisons of catches at different heights and directions, the same stakes were used, but the tips were cut off to make them 10 in. long. These were stapled vertically to the sides of 2 x 2 in. posts painted white. Thus a height of 1 ft. actually means that the stake was 1 ft. to 1 ft. 10 in. above ground level. The garden stakes were coated with a thin layer of Stickem® and examined at least twice weekly during the

1Research Entomologist and Agricultural Research Technician, respectively. ARS, USDA, Kimberly, Idaho 83341. 2Numbers in parenthes refer to literature cited.

http://Ot.it.idae

VOL. 19, No. 2, OCTOBER 1976 113

flight period, May and June . At each examination flies were counted and removed, and the sticky coating was renewed. In 1968-70, twenty such posts were set up at 3-mile intervals along roadsides in the beet growing area from Paul to Minidoka, Idaho. In 1971, ten of the same 20 locations, where the greatest number of flies had been trapped previously, were used again. In l975, rough, unpainted lath posts were compared with the 2 x 2 in. white posts. Also in 1974 and 1975, stakes were maintained in a series of survey fields where, in mid-season, maggot populations were determined in untreated check plots by sifting cores of soil each containing a beet. In 1975, damage ratings (1) were obtained at mid,season. Data in 1974 and 1975 were obtained in cooperation with research personnel of The Amalgamated Sugar Company and the Utah-Idaho Sugar Company. Unless otherwise stated, all work was done in south-central Idaho.

Results The effect of color on fly catches is summarized in Table 1. The

data from Swenson and Peay (3) are included. All data are presented as percentage of the number of flies caughton black stakes since black was included in all 6 years of testing and averaged better than green (the only other color present in all years). Colors ranked in essentially the same order each year: red and orange caught more flies than black in 4 of 5 comparisons. The lighter colors (yellow, white, silver, and unpainted) consistently caught fewer flies. Blue, brown, and green were intermediate and seldom attracted as many flies as black. Orange is our color of choice since there appears to be little, if any, difference between it and red, and the black-bodied flies are more easily identified and counted on the lighter background.

The effect of stake height on fly catches is summarized in Table 2. In 1968 when stakes were placed from ground level to 7 ft., those with the stake bottom 1 ft. above ground level caught 48.1% of the total trapped. Lesser numbers were caught above and below this level. In


subsequent years, stakes at the 1-ft. level invariably caught more flies than stakes at the 2 or 3-ft. levels.

The effect of trap exposure (compass direction) is summarized in Table 3. Duncan's multiple range test showed north to be superior to the other directions though east did not differ significantly from north at the 5% level.

Because rough laths are relatively cheap and require no preparation as compared with the 2 X 2 in. posts painted white, the two were compared in 1975. Three of each were placed in pairs on the margins of 9 survey fields in south-central Idaho. Orange sticky stakes were stapled at the l-ft. level facing east. The results are shown in Table 4. A t test showed that significantly more flies were caught by stakes mounted on the white posts.

The relationships between sticky stake fly catches and maggot counts in 1974 and 1975 are given in Table 5. Correlations were highly significant except for the series of 8 survey fields in eastern Idaho in 1974. The changes in stake color and exposure from 1974 to 1975 are

VOL. 19, No. 2, OCTOBER 1976 115

c o n s i d e r e d t o be o f no c o n s e q u e n c e . T h e 1974 d a t a for e a s t e r n I d a h o s h o w e d a non-s ignif icant c o r r e l a t i o n . Plots in e a s t e r n I d a h o w e r e establ ished by p e r s o n n e l of U t a h - I d a h o S u g a r C o m p a n y (now U & I , Incorp o r a t e d ) . T h e s e plots w e r e of ten n a r r o w s t r ips b o u n d e d by t r e a t e d a reas a n d t h e i r exac t locat ion a n d h is tory was s o m e t i m e s u n c e r t a i n . We , t h e r e f o r e , c o n s i d e r t h e s e d a t a t o con ta in e r r o r s m a r k e d l y affecting resul ts . W h e n we c o m b i n e d t h e d a t a for 1974 (9 fields) a n d 1975 (3 f ie lds) in s o u t h - c e n t r a l I d a h o , a co r r e l a t ion va lue of 0 . 9 1 * * was ob t a ined w h i c h m e a n s t h a t 8 2 % o f t h e var ia t ion i n m a g g o t p o p u l a t i o n s cou ld be e x p l a i n e d by var ia t ions in fly p o p u l a t i o n s as m e a s u r e d by t h e sticky s take t r a p s .

T h e r e l a t i o n s h i p b e t w e e n f l y p o p u l a t i o n s a n d d a m a g e r a t ings i s p r e s e n t e d in F i g u r e 1. Of a total of 12 sets of da t a avai lable , two w e r e d i s c a r d e d because n o f l i e s w e r e t r a p p e d a n d d a m a g e r a t ings w e r e also e i t he r ze ro or nea r ly so. A t h i r d set was d i s c a r d e d d u e to an obv ious e r r o r . T h e co r r e l a t i on for t h e r e m a i n i n g d a t a ( n = 9 ) was . 9 1 * * . T h e r eg res s ion f o r m u l a is g iven in F i g u r e 1.

S u m m a r y a n d C o n c l u s i o n s E i t h e r o r a n g e or r e d sticky s t ake t r a p s 1 x 10 in. s t ap l ed vert ical ly

with t h e b o t t o m s 1 ft. above g r o u n d level on whi te 2 x 2 in. posts facing e i t he r east o r n o r t h a n d loca ted a t t h e m a r g i n s o f s u g a r b e e t f i e l d s w e r e f o u n d to be s u p e r i o r t o o t h e r colors , he igh t s , a n d e x p o s u r e s i n t r a p p i n g a d u l t s u g a r b e e t r o o t m a g g o t s . A n a d d i t i o n a l a d v a n t a g e o f o r a n g e - c o l o r e d t r a p s i s t h a t f l i es a r e m o r e easily ident i f ied on this b a c k g r o u n d t h a n on d a r k e r colors . A d v a n t a g e s of p l ac ing s takes 1 ft. above g r o u n d r a t h e r t h a n s imply s t icking p o i n t e d g a r d e n s takes i n t h e g r o u n d i s t h a t t h e h i g h e r level collects less d i r t a n d t r a sh , a n d b i rds a r e less likely to r e m o v e t h e f l i e s . In t h e a r e a o f o u r tests, p r eva i l i ng w i n d s a r e f rom t h e west o r sou thwes t , a n d this m a y be t h e r e a s o n why we h a d l a r g e r f l y ca tches o n n o r t h a n d eas t e x p o s u r e s . T h e n u m b e r o f flies t r a p p e d with o r a n g e a n d black s takes m o u n t e d a t t h e 1-ft. level a n d e x p o s e d t o n o r t h o r east d i r ec t ions w e r e f o u n d i n 1974 a n d 1975 t o co r re l a t e well wi th b o t h m a g g o t p o p u l a t i o n s a n d d a m a g e r a t i ngs . Such c oun t s t h u s can b e u s e d t o p r ed i c t m a g g o t p o p u l a t i o n s a n d d a m a g e ra t ings .

We propose to standardize survey stakes as shown in Figure 2.


VOL. 19, No. 2, OCTOBER 1976 117

Literature cited (1) BLICKENSTAFF, C. C, R. E. PECKENPAUGH, and G. G. MAHRT. 1976. In press. J. Am. Soc. Sugar Beet Technol. (2) MAERZ, A. and M. R. PAUL. 1930. A Dictionary of Color. McGraw-Hill Book Co., Inc. New York, NY 207 pp. (3) SWENSON, A. A. and W. E. PEAY. 1969. Color and natural products attracting the adult sugarbeet root maggot in South-central Idaho. J. Econ. Entomol. 62(4):910-912.

A c k n o w l e d g m e n t ts

Data for t h e years 1968 t h r o u g h 1971 w e r e g a t h e r e d by A. A . Swenson a n d W. E . Peay, f o r m e r p e r s o n n e l o f t h e l a b o r a t o r y .

Soil Nitrate and the Response of Sugarbeets To Fertilizer Nitrogen

F . J . H I L L S a n d A L B E R T U L R I C H 1

Received for publication May 4, 1976

T h e efficient use of n i t rogen fertilizer in sugarbeet (Beta Vulgaris L.) culture is an important factor in maximizing sugar production, conserving fertilizer supplies, and minimizing the pollution of ground water by the downward movement of nitrate. Fields on which sugar beets are grown differ markedly in the amount of fertilizer nitrogen required for maximum sugar yield. Some need none while others require up to 240 lb N per acre. Thus, efficient fertilization requires a specific recommendation for each field.

Procedures for estimating fertilizer nitrogen from soil nitrate early in the growing season have been advanced. James et al. (4)2

summed the concentration of soil nitrate to a depth of 6 feet and found only one responsive site where this index exceeded 30 (ca. 120 lb N03-N/acre) . Giles et al. (2) concluded that sugar responses to fertilizer N are unlikely when soil N O 3 to a depth of 2 feet exceeds ca. 120 lb N/acre. Carter and his colleagues (1) improved on the fertilizer recommendations of fieldmen which were based on field history by determining mineralizable NO3 in addition to residual NO3 to a depth of 3 feet; modifying both determinations by factors to reflect efficiency of uptake; subtracting the sum of these quantities from the amount estimated to be needed by the expected crop to obtain the amount of fertilizer N needed; and then increasing this amount by a factor to reflect efficiency of fertilizer N uptake.

One objective for conducting the field trials reported here was to assess and, if possible, calibrate soil analyses for NO3-N to use in predicting the needs of crops for fertilizer nitrogen in the sugar beet growing areas of California.

Materials and Methods Twenty field trials were conducted from 1971 through 1974.

Phosphorus was applied to all plots at all locations where this nutrient may have been needed. Ammonium nitrate was applied after seedlings had emerged but not later than thinning time, usually at rates of 0, 60, 120, 1 80, 240, and 300 lb N/acre. The fertilizer was sidedressed 8 to 10 inches from the sugar beet rows, usually on both sides. Plots were six rows wide and at least 50 feet long. Rates were replicated five or six times. At harvest, plants of the center two rows of each plot were dug

1Etension Agronomist, University of California, Davis, and Plant Physiologist, Emeritus, University of California, Berkeley, respectively.


VOL. 19, No. 2, OCTOBER 1976 119

a n d t o p p e d below the oldest living leaf. Roo ts w e r e c o u n t e d a n d two samples , o f a b o u t 10 roo t s each , w e r e t aken for t a r e a n d suc rose analyses by s u g a r factory t a r e l abora to r i e s .

Soil co res w e r e t a k e n j u s t p r i o r to fer t i l izat ion, usual ly with a soil t u b e a b o u t 1 inch in d i a m e t e r . At least t h r e e cores w e r e t aken f rom each of a t least four nonfe r t i l i zed plots a n d c o m p o s i t e d by foot d e p t h s to a t least 4 feet. Soil s ample s w e r e f rozen or oven d r i e d wi thin 24 h o u r s of col lect ion. Five g r a m s of d r y soil w e r e e x t r a c t e d by s h a k i n g with 25 ml silver sulfa te so lu t ion (3 .5 g Ag2S04/ l i ter ) , f i l tered, a n d the ex t rac t ana lyzed for NO.) by t he p h e n o l d i s u l f o n i c acid m e t h o d (.5). F r o z e n sample s w e r e t h a w e d a n d w a t e r a d d e d with s t i r r ing to fo rm a s a t u r a t e d pas te . N i t r a t e was d e t e r m i n e d in t h e ex t r ac t as for d ry s ample s . Resul ts w e r e r e p o r t e d on a d r y soil basis.

Resu l t s and D i s c u s s i o n

In 5 of t h e 20 trials t h e r e w e r e factors o t h e r t h a n n i t r o g e n n u t r i tion which obviously af fec ted yield a n d , t h e r e f o r e , t h e resul ts cou ld no t be used for ca l ib ra t ion p u r p o s e s . T h e s e 5 tr ials have b e e n o m i t t e d f rom this s u m m a r y .

T h e r o o t yield o f e a c h t r ia l g iv ing m a x i m u m s u g a r p r o d u c t i o n a n d the associa ted fert i l izat ion r a t e was d e t e r m i n e d by fit t ing roo t a n d s u g a r yield r e s p o n s e c u r v e s t o t h e m e a n values o b s e r v e d for each r a t e of n i t r o g e n fert i l izer as i l lus t ra ted in F igu re 1 . Root yields giving m a x i m u m s u g a r p r o d u c t i o n va r i ed f rom 27 t o 46 tons /ac re a n d the fertil izer N r e q u i r e d to p r o d u c e t he se yields var ied f rom 0 to 2 4 0 lb N/ac re . Data f rom all fifteen trials a r e s u m m a r i z e d in T a b l e 1.


In F igu re 2 t he a v e r a g e roo t yield of unfe r t i l i zed plots a t each locat ion is e x p r e s s e d as a p e r c e n t of t h e a v e r a g e r o o t yield of plots ferti l ized for m a x i m u m s u g a r p r o d u c t i o n a n d p lo t t ed aga ins t soil

VOL. 19, No. 2, OCTOBER 1976 121

nitrate. There is little basis for quantifying the response to nitrogen fertilizer to the level of soil nitrate, as implied by the eye fitted curve, except to note a possible critical value of about 250 lb NO3-N per acre 3 feet of soil. Only one of five crops responded to fertilizer N when soil nitrate exceeded this level. For soil N O 3 - / a c r e 2 feet, the comparable critical value was about 200 lb.

An emperical nitrogen requirement (Nr) based on soil and fertilizer N can be determined from experiments where there are responses to fertilizer as the amount of nitrogen required per unit of root yield for the crop that produces maximum sugar. For example, referring to Table 1, Nr = (Ns + Nf)/Ye. Thus for trial 771, Nr = (153 lb soil N O 3 / c r e 3 ft + 60 1b fertilizer N/acre)/32.0 tons/acre = 6.7 lb N/ton of roots. Nr reflects the efficiency of uptake of both soil and fertilizer N. If these efficiencies do not vary too greatly among fields, an average Nr can be used to determine the demand for soil plus fertilizer N for any given field by multiplying Nr by the root yield expected for maximum sugar yield. Then, fertilizer N, (Nf) can be determined by subtracting soil N. Thus Nf = Ye(Nr)—Ns. For the 11 trials of Table 1 where there was a response to fertilizer, the calculated Nr ranged from 4.56 to 13.42 with mean 8.49 (±0.56)3 lb N/ton. This mean value for Nr was used to determine the soil NO3-N plus fertilizer N needed for maximum sugar yield for each trial. Subtracting soil NO3-N/acre 3 feet gave an estimate of fertilizer N, e.g. for trial 771, Nf = 32.0(8.49)—153 = 1 19 lb fertilizer N. Estimates of fertilizer N were within what might be considered an acceptable deviation of ± 20 lb/acre in only 4 trials. Though this procedure does not appear to be satisfactory, it might be improved by determining miner alizable N, as proposed by Carter et al. (1).

From the data of Table 1 the amount of fertilizer nitrogen required per ton of increase in root yield was estimated for each trial where there was a response to fertilizer by dividing the amount of fertilizer N required for maximum sucrose yield by the difference between the root yield producing maximum sucrose and the root yield with no fertilizer to give lb fertilizer N/ton of root yield increase (Nfr). Thus Nfr = Nf/(Ye—Yo). For the 1 1 trials this fertilizer N requirement ranged from 12.24 to 22.02 and averaged 16.1 (±0.87) lb N/ton root yield increase.

Using 16.1 lb fertilizer N per ton of root yield increase and the known response to fertilizer for the trials of Table 1, the fertilizer N required to produce maximum sugar can be predicted to within ±20 lb in 87% of the trials (13 out of 15). Thus, for a given field, if root yield can be estimated for nonfertilized beets and for beets fertilized to produce maximum sugar, the difference in root yield multiplied by 16 lb N/ton gives an estimate of fertilizer N needed, i.e. Nf = (Ye—Yo)Nfr.

3Standard error of the mean.


R o u g h es t imates of root yield to be e x p e c t e d w h e n a c r o p is n o t ferti l ized m i g h t be d e t e r m i n e d f rom soil n i t r a t e a t t h e b e g i n n i n g of t he g r o w i n g season . Coefficients o f l inear d e t e r m i n a t i o n (r2) r e l a t ing m e a n roo t yields of nonfer t i l i zed plots to soil N O 3 - N to a p a r t i c u l a r d e p t h of s a m p l i n g w e r e : 0-1 foot, 0 .47; 0-2 feet, 0 .62; 0-3 feet, 0 .63 ; a n d 0-4 feet, 0 . 6 1 . T h e fai lure to i m p r o v e t h e coefficient o f d e t e r m i n a t i o n by s a m p l i n g below 3 feet sugges t s t h e r e is little to gain by d e e p e r s a m p l i n g . In fact, s a m p l i n g to 2 feet gave near ly as g o o d a co r r e l a t i on b u t since s u g a r beet roots readi ly p e n e t r a t e 3 feet in a d e e p , we l l -d ra ined soil, i t a p p e a r s r e a s o n a b l e to s a m p l e to this d e p t h .

Based on these 1 5 fields, an e q u a t i o n to p red i c t r oo t yeild f rom soil n i t r a t e is Yo = 20 .5 + 0 .044 (lb N O 3 - N / a c r e 3 feet), w h e r e Yo = roo t yield w i thou t ferti l izer N, r = 0 .794***, (F igu re 3). T h e fact that this r e l a t ionsh ip a c c o u n t e d for 6 3 % o f t h e var ia t ion a m o n g roo t yields o f d i f fe ren t fields is ev idence tha t t h e a m o u n t of soil n i t r a t e ear ly in t h e season i s an i m p o r t a n t factor af fec t ing p r o d u c t i o n . To es t ima te roo t yield based on soil n i t r a t e to a d e p t h of 2 feet, t he r eg re s s ion e q u a t i o n is: Yo = 20.4 + 0 .058 (lb N O a - N / a c r e 2 feet), r = 0 .785***. The two equa t i ons es t ima te c o m p a r a b l e roo t yields at low levels of soil n i t r a t e but , d u e to a s t e e p e r s lope, t h e la t te r p red ic t s h i g h e r roo t yields as soil N O 3 - N increases , par t i cu la r ly above 100 lb/acre 2 feet.

Based on these resul ts , a p r o c e d u r e for e s t ima t ing fert i l izer N is t he fol lowing. 1) Es t imate e x p e c t e d roo t yield for m a x i m u m s u g a r p r o d u c t i o n (Ye) f rom c r o p his tory. 2) Es t imate roo t yield w i t h o u t N fertil izer (Yo) f r o m t h e e q u a t i o n Yo = 20 .5 + 0 .044 Ns , w h e r e Ns = lb soil N O 3 - N / a c r e 3 feet ear ly in t h e season . 3) Es t ima te fert i l izer N (Nf) by Nf = (Ye-Yo)Nfr , w h e r e Nfr = 16 lb fert i l izer N / t o n of roo t yield

Figure 3. — Relation of root yield in unfertilized plots to soil nitrate-nitrogen determined early in the growing season for 15 locations.

VOL. 19, No. 2, OCTOBER 1976 123

increase. Utilizing this procedure, Table 2 gives estimates of fertilizer N based on varying levels of soil NO 3 and expected root yields of 30 and 35 tons/acre.

It should be noted that estimated fertilizer N can and will vary considerably from the actual requirement due to the variability not accounted for by the regression for estimating yield without fertilizer from soil nitrate, the failure of a sampling procedure to estimate the amount of soil nitrate actually present, and a poor estimate of root yield for the fertilized crop due to unexpected changes in weather, pest and disease infestation, or other unforeseen factors.

Regardless of the procedure used to estimate fertilizer N, it is important to evaluate how well applied fertilizer meets the needs of the crop. This can best be done by a plant analysis program and reference to a well-defined critical level to determine the adequacy of nitrogen supply and when plants become deficient (6). Anticipated early season deficiencies may be corrected and a knowledge of late season deficiencies can aid in deciding which fields are to be harvested first (6, 3). In addition, plant samples can be analyzed to determine if the fertilizer program is also meeting the needs for other nutrients known to affect sugar beet growth (6, 7).

Table 2. Nitrogen fertilizer rates estimated from soil nitrate and expected root yield.

1Calculated from root yield = 20.5 + 0.044 (lb soil NO3-N/acre 3 feet). 2(Expected root yield with fertilizer — root yield with no fertilizer) 16 lb N/ ton .

Summary Field trials to determine fertilizer N required for maximum suc

rose yield were conducted at 15 locations throughout the beet growing areas of California. The root yield to be expected without fertilization (Yo) can be estimated from the equation Yo = 20.5 + 0.044 Ns, where Ns = NO3-N/acre 3 feet of soil early in the growing season. The amount of fertilizer N required per ton of increase in root yield averaged about 16 lb N per ton. Fertilizer nitrogen (Nf) for maximum sugar production can be estimated by Nf = (Ye-Yo) Nfr; where Ye = expected root yield based on field history, Yo = root yield expected without N fertilizer based on soil nitrate, and Nfr = fertilizer N required/unit of root yield increase from Yo to Ye.

124 JOURNAL OF THE A.S.S.B.T

A c k n o w l e d g m e n t T h e f i e ld trials r e p o r t e d w e r e c a r r i e d o u t by Univers i ty o f Califor

n ia F a r m Advisors R. L. Sailsbery, D. R. Woodru f f , R. W. H a g e m a n n , H. L. Hal l , W. E. B e n d i x e n , P. P. Os ter l i , B. B. Fischer , F. R. Kegel , a n d E.F . N o u r s e ; U C M o r e n o Field Sta t ion S u p e r i n t e n d e n t P.W. M o o r e ; a n d Staff Resea rch Associate G.R. P e t e r s o n ; a n d w e r e f inanced in p a r t by g r a n t s f r o m the Cal i forn ia s u g a r b e e t p rocesso r s a n d t h e Cal i forn ia Beet G r o w e r s Associat ion. Soil analyses w e r e u n d e r t h e supe rv i s ion o f J . E . Quick , supe rv i so r o f t h e UC C o o p e r a t i v e E x t e n s i o n soils l abora tory .

Literature Cited (1) CARTER, J. N., D. T. WESTERMANN, M. E . JENSEN, and S. M. BOSNIA. 1975.

Predicting nitrogen fertilizer needs for sugarbeets From residual nitrate and mineralizable nitrogen. J. Am. Soc. Sugar Beet Technol. 18: 232-243.

(2) GILES, J. F., J. O. REUSS, and A. E. LUDWICK. 1975. Prediction of nitrogen status of sugarbeets by soil analysis. Agron. J. 67: 454-459.

(3) HILLS, F.J . and A. ULRICH. 1971. Nitrogen nutrition. In R. T . Johnson et al. (ed) Advances in sugarbeet production. p. 111-136. Iowa State University Press, Ames.

(4) JAMES, D. W., A. W. RICHARDS, W. H. WEAVER, and R. L. REEDER. 1971. Residual soil nitrate measurement as a basis for managing nitrogen Fertilizer practices for sugarbeets. J. Am. Soc. Sugar Beet Technol. 16: 313-322.

(5) JOHNSON, C. and A. ULRICH. 1959. Analytical methods for use in plant analysis. Bull. 766: 26-78. Division of Agr. Science, University of California, Berkeley.

(6) ULRICII , A. and F .J . HILLS. 1967. Plant analysis as an aid in fertilizing sugar crops: Part I. Sugarbeets . In L. M. Walsh and J. D. Beaton (eds.) Soil Testing and plant analysis (Revised Ed.) p. 271-288. Soil Sci. Soc. of Amer., Madison, Wisconsin.

(7) ULRICH, A. and F.J . HILLS. 1969. Sugar beet nutrient deficiency symptoms, a color atlas and chemical guide. University of California, Division of Agr. Sci., Berkeley. 36 p.

Competition of Annual Weeds and Sugarbeets1

STEVEN R. W I N T E R a n d A L L E N F . W I E S E 2

Received for publication December 2, 1975

Annual weeds are a major problem in sugarbeet production on the Texas High Plains. T h e most widespread and troublesome annual weeds are kochia (Kochia scoparia (L.) Schrad.), pigweed (mostly Amaranthus Retroflexus L. and A. palmeri S. Wats . ), and barnyardgrass (Echinochloa crus-galli (L.) Beauv.).

Broadleaf annual weeds have been shown to be more competitive with sugarbeets than grasses (1 , 2, 4)3 . Green foxtail (Setaria viridis (L.) Beauv.) densities of less than one foxtail per sugarbeet plant did not reduce sugarbeet root yield significantly in Wyoming (1). In the same study, one rough pigweed (Amaranthus retroflexus L.) per e ight sugarbee ts significantly r educed sugarbee t root yield. In New York, mus t a rd (Brassica spp.) was more compet i t ive t h a n yellow foxtail (Setaria glauca L.) Beauv.) (4). T h e greater yield loss caused by broadleaf weeds appears to be due to their superior ability to compete for light.

In Washington, weeds that emerged soon after sugarbeet planting and competed until harvest r educed root yield the most (2). If weeds were removed within 9 weeks after sugarbeet emergence, yield was not r e d u c e d . When sugarbee t s were h a n d weeded for 7 to 9 weeks after sugarbeet emergence, full-season weed cont ro l resu l ted because c rop compet i t ion con t ro l led weeds that emerged later.

In most cases, yield reductions caused by annual weeds can be largely explained by the shading effect of weeds on the sugarbeets. T h e r e can also be compet i t ion for water or nu t r i en t s . Donald (3) gives an in-depth discussion of competition between plants. He explains how interactions compound advantages to the species able to dominate light interception. When a species falls behind on light in tercept ion, it has a r educed ability to effectively utilize its diminishing share of the water and nutr ients . This in t u r n causes a fu r the r r educ t ion in ability to compete for light.

1Cooperative investigations of the Texas Agricultural Experiment Station, and Agricultural Research Service, U.S. Department of Agriculture. Approved for publication as Texas Agricultural Experiment Station Technical Article No. 1221 1.

2Assistant Professor and Professor, Texas Agricultural Experiment Station, USDA Southwestern Great Plains Research Center, Bushland, Texas, 79012.



Sucrose c o n c e n t r a t i o n of s u g a r b e e t roo t s is affected m u c h less by w e e d c o m p e t i t i o n t h a n i s r o o t y i e l d . D a w s o n (2) f o u n d t h a t s u c r o s e c o n c e n t r a t i o n was r e d u c e d o n l y w h e r e r o o t y ie ld was r e d u c e d by m o r e t h a n 63%.

Most suga rbee t g r o w e r s in t h e T e x a s P a n h a n d l e use only a postl a y b y h e r b i c i d e a p p l i e d w h e n t h e s u g a r b e e t s h a v e 8 t o 1 6 leaves . H a n d l a b o r a n d cu l t i va t i on a r e u s e d p r i o r t o t h a t t i m e . T h e s e s t u d i e s w e r e u n d e r t a k e n t o d e t e r m i n e w h e n y i e ld r e d u c i n g w e e d s e m e r g e a n d h o w l o n g w e e d s c a n r e m a i n i n s u g a r b e e t s b e f o r e y i e l d s a r e r e d u c e d . T h i s i n f o r m a t i o n will h e l p f o r m u l a t e m o r e e f f e c t i v e c h e m i c a l a n d c u l t u r a l w e e d con t ro l systems.

Materials and Methods T o d e t e r m i n e how l o n g weeds cou ld c o m p e t e with s u g a r b e e t s

w i t h o u t d e p r e s s i n g y i e l d , p l o t s w e r e h a n d w e e d e d a t 2 , 4 , 6 , a n d 8 w e e k s a f t e r s u g a r b e e t e m e r g e n c e a n d t h e n k e p t w e e d f r e e u n t i l h a r v e s t . O t h e r p l o t s w e r e k e p t w e e d - f r e e fo r 2 , 4 , 6 , a n d 8 weeks a f te r s u g a r b e e t e m e r g e n c e a n d t h e n a l lowed to b e c o m e w e e d y t o f i nd o u t w h e n e m e r g i n g w e e d s w e r e n o l o n g e r c o m p e t i t i v e t o t h e c r o p . P i g w e e d s e e d w a s b r o a d c a s t o n all p l o t s j u s t b e f o r e e m e r g e n c e i r r i g a t i o n . O t h e r w e e d s p r e s e n t w e r e k o c h i a a n d b a r n y a r d g r a s s . T h e two c h e c k t r e a t m e n t s w e r e w e e d - f r e e a n d w e e d y f o r t h e e n t i r e g r o w i n g season . W e e d s w e r e a l lowed to g r o w only in an e igh t - i nch b a n d c e n t e r e d o n t h e s u g a r b e e t r o w . W a t e r f u r r o w s b e t w e e n r o w s w e r e c u l t i v a t e d t o f a c i l i t a t e f u r r o w i r r i g a t i o n . A r a n d o m i z e d c o m p l e t e b l o c k d e s i g n w i t h f o u r r e p l i c a t i o n s w a s u s e d b o t h years .

In 1972, Hol ly H H 1 0 s u g a r b e e t s w e r e p l a n t e d March 13 on 30-i n c h b e d s a n d i r r i g a t e d o n M a r c h 1 4 f o r e m e r g e n c e . P l o t s w e r e two rows w i d e a n d 5 0 feet l o n g . I n O c t o b e r , w e e d s w e r e h a r v e s t e d f r o m b o t h row's a n d s u g a r b e e t s f r o m 4 5 ft. o f o n e row.

Detai ls of t h e e x p e r i m e n t in 1973 w e r e s imi lar to 1972 excep t t ha t plots w e r e f o u r rows wide a n d 30 ft. l ong . T h e c e n t e r two rows w e r e h a r v e s t e d for w e e d a n d s u g a r b e e t y ie ld i n O c t o b e r . W e t , cold w e a t h e r d e l a y e d p l a n t i n g un t i l May 2 , a b o u t 6 weeks l a t e r t h a n n o r m a l . T h e s t u d y was i r r i ga t ed on May 3 for e m e r g e n c e .

Resul t s and D i s c u s s i o n

In 1972, a b o u t o n e weed e m e r g e d p e r foot o f row in t h e w e e d y c h e c k ( T a b l e 1). P i g w e e d p r e d o m i n a t e d b u t a few k o c h i a a n d b a r n y a r d g r a s s p l a n t s w e r e p r e s e n t . S u g a r b e e t s t h a t w e r e k e p t w e e d - f r e e for 6 w e e k s o r l o n g e r a f t e r s u g a r b e e t e m e r g e n c e o n

VOL. 19, No. 2, OCTOBER 1976 127

March 23 yielded nearly as much as those kept weed-free for the entire growing season. Only a few pigweed emerged later than 6 weeks after sugarbeet emergence and at harvest were only about one-half as tall as those that emerged earlier. Kochia plants were almost eliminated when hoed 4 weeks after sugarbeet e m e r g e n c e . B a r n y a r d g r a s s con t inued to e m e r g e for 6 weeks and a few pigweed e m e r g e d after 8 weeks. Allowing weeds to grow and compete with sugarbeets for 8 weeks before weeding did not reduce yields.

Pigweed, at 2.4 plants per foot of row, was the only weed present in significant numbers in 1973. Removing weeds at 4 weeks or later after sugarbeet emergence on May 14 nearly el iminated pigweed for the year (Table 2). C o n t r a r y to 1972 resul ts , pigweed allowed to grow for 8 weeks with sugarbeets competed significantly and r e d u c e d yield. T h e ear l ie r onset of yieldr educ ing weed compet i t ion in 1973 can be a t t r i bu t ed to a heavier weed stand and later planting which resulted in more rap id deve lopmen t of weeds. When weeds were removed at 8 weeks, sugarbeet plants were severely s tunted compared to weed-free sugarbee t s . After weed removal , sugarbee t s appeared to recover, but yields were reduced in the fall.

This work demonstrates the overriding importance of early season weed control . T h e greatest number , most competitive, and potentially tallest weeds emerge early. A successful weed control system for the Texas Panhandle needs to be built around effective preplant and early postemergence herbicides.

Summary For 2 years in areas infested predominantely with pigweed, and to

a lesser ex ten t with kochia and ba rnya rdg ra s s , cer tain plots of sugarbeets were weeded for 2, 4, 6, or 8 weeks after sugarbeet emergence. Weeds were then allowed to emerge and grow until harvest . In o the r plots , weeds compe ted initially with sugarbeets for 2, 4, 6, or 8 weeks and then the plots were kept weed-free until harvest.

I.ate emerging weeds did not greatly influence the yield of sugarbeets when the sugarbee ts were kept weed-free for 6 weeks after emergence . Weeds that were allowed to grow and compete with sugarbeets for 8 weeks after sugarbee t emergence reduced yield in one of two years. Control of early weeds within 6 weeks after sugarbee t e m e r g e n c e near ly e l iminates weed competition for the season and is essential for maximum sugarbeet yield. Research effort should be concentrated on developing effective p r e p l a n t and early p o s t e m e r g e n c e herb ic ide systems.

Table 1. — Weed and sugarbeet yields in October after various periods of competition, 1972.

*Means followed by the same letter do not differ at the 5% level according to Duncan's New Multiple Range Test.

VOL. 19, No. 2, OCTOBER 1976 129

Table 2. — Pigweed and sugarbeet yield in October after various periods of competition, 1973.

*Means followed by the same letter do not differ at the 5% level according to Duncan's New Multiple Range Test.

Literature Ci ted (1) BRIMHALL, PHIL B., EARL W. CHAMBERLAIN, and H. P. ALLEY. 1965. Compe

tition of annual weeds and sugarbeets. Weeds 13:33-35. (2) DAWSON, J. H. 1965. Competition between irrigated sugarbeets and

annual weeds. Weeds 13:245-249. (3) DONALD, C. M. 1963. Competition among crop and pasture plants.

In A. G. Norman (ed.) Advances in Agronomy. 15:1-118. Academic Press, New York, New York.

(4) ZIMDAHL, ROBERT L. and STANFORD N. FERTIG. 1967. Influence of weed competition on sugarbeets. Weeds 15:336-339.

Effect of Crown Material on Yield and Quality of Sugar Beet Roots:

A Grower Survey1

D. F. COLE AND G. J . SEILER2

Received for publication March 22, 1976

Summary A survey of commercial sugar beet growers in the Red River Valley of

Nor th Dakota and Minnesota was conducted to determine the change in tonnage and root quality tht would occur if sugar beets were flailed ra ther than topped conventionally at harvest. T h e da ta indicated that the growers removed only 2 0 % of the crown mater ial by topping, which reduced tonnage by 5 % .

Removal of all the crown mater ia l by h a n d resulted in a 1.2% increase in sucrose and a 7 . 1 % reduction in ni t ra te g rade . Sugar beet crown material accounted for 2 0 . 5 % of the tonnage delivered to the factory.

Introduction Sugar beets are normally flailed and scalped before harvesting. T h e

purpose of scalping is to remove a port ion of the crown, which is the area above the lowest leaf scar. Crown material is known to be higher in impurities and lower in sucrose relative to the main body of the sugar beet root. More sugar per acre can be recovered from beets which are only flailed before harvesting (1 , 6) . 3 This increase can come about for several reasons: sugar can be extracted from the crown mater ial , respiration losses dur ing storage would be reduced by not cutt ing the crown, and the amoun t of rot would be reduced by not exposing the most susceptible tissue, the center port ion of the crown.

If sugar beets were only flailed at harvest, an increase in tonnage and a reduction in percent sucrose would be expected. However, no da ta are available to indicate the ant icipated change in either tonnage or percent sugar. A survey at one location in the Red River Valley in the 1974-75 processing campaign indicated that only 6% of the sugar beets were topped at the lowest leaf scar, 7 1 % were partially topped, and 2 3 % were only flailed (2). Thus , a considerable a m o u n t of crown tissue is being processed at the present t ime.

A survey of commercial sugar beet growers was conducted dur ing the week of September 29 to October 3, 1975, in the Red River Valley to determine the change in tonnage and root quality tha t would occur if sugar beets were only flailed at harvest.

1Cooperative investigation of the Agricultural Research Service, U.S. Department of Agriculture, and the Agricultural Experiment Station, Nor th Dakota State University, Fargo, ND 58102. Published with the approval of the Director of the Nor th Dakota Agricultural Experiment Station as Journal Paper No. 7 2 7 .

2Research Plant Physiologist and Research Technician, respectively. 3Numbers in parentheses refer to l i terature cited.

VOL. 19, No. 2, OCTOBER 1976 131

Materials and Methods

Sugar beet samples were obta ined from randomly selected growers in each of the six factory districts in the Red River Valley. Four 10-beet samples were harvested from each grower a n d / o r location in a field. In each field, samples were obta ined from rows adjacent to where the grower had temporari ly stopped scalping. From the row which had not been flailed or scalped, two 10-beet samples were manual ly harvested. T h e leaves were removed from both samples at the base of the petiole with a knife. T h e crowns were removed from one sample at the lowest leaf scar and weighed. T h e 10 topped roots and the 10 un topped roots were then placed into a " tare bag" for further analysis. Two 10-beet samples were manual ly harvested from the adjacent row where the grower had flailed and scalped the sugar beets. T h e remain ing crown tissue on one sample was removed and weighed. Roots of bo th samples were placed into tare bags. Length of row harvested for each 10-beet sample was de termined. Row width was 22 inches in all fields and 68 locations were sampled. Flailed samples were obtained from an addit ional six fields in the East Grand Forks, Minnesota area. Grower-scalped samples were not obta ined on these six fields because the factory was not receiving beets at the t ime of the survey.

T h e tare bags were t ransported to the tare laboratory of Amer ican Crystal Sugar Company at East Grand Forks, Minnesota. At the tare laboratory, the roots were washed, weighed, and sawed to obta in pulp for determinat ion of sucrose, n i t ra te grade , and conductivity g rade . Percent crown tissue was calculated using the weight of the crown mater ia l removed as a percentage of the original root weight.

Two samples of sugar beet roots were obta ined from grower trucks at each of six piling stations in the valley. Samples obta ined at Crookston factory, Midway, Hillsboro factory, Drayton factory, and Hami l ton consisted of 10 roots selected at r andom from a loaded truck. Samples were obta ined from the Moorhead factory by using the sample bucket on the piler to catch two samples per truck load. One sample from each load was topped to the lowest leaf scar to de te rmine the weight of the crown mater ia l that was delivered to the factory by the grower. Sucrose, n i t ra te grade , and conductivity grade were measured on both samples at the East Grand Forks tare laboratory.

Results and Discussion Average length of row to harvest 10 sugar beets varied from 11.6 to

12.1 ft (Table 1), indicative of an average popula t ion of 19,721 to 20,434 plants per acre. Sugar beet roots harvested from the grower-scalped row were lower in sucrose than were sugar beets harvested from the row with intact leaves used to simulate flailing. T h e reduced sucrose levels probably resulted from normal respiration which is increased by scalping; also the leaves had been removed from the grower-scalped sugar beet roots for an unde te rmined t ime period, thereby el iminat ing photosynthesis and preventing further sucrose storage. T h e flailed sugar beets were capable of

Table 1. Length of row to harvest 10 beets, sucrose, nitrate, conductivity, percent crown, and yield averaged over all growers.

†l) Flailed; 2) flailed, crown removed manually; 3) grower-topped; 4) grower-topped, remaining crown removed manually. ††Mean with standard error of the mean.

VOL. 19, No. 2, OCTOBER 1976 133

photosynthesis and storage up to harvest. T h e lower sucrose percentage in the grower-scalped row may have resulted from water uptake by the roots after scalping.

Removal of the entire crown (sample 2, Tab le 1) resulted in a 1.2% increase in sucrose, a 7 . 1 % reduct ion in n i t ra te grade , a 5% reduct ion in conductivity grade , and an 18 .6% reduct ion in yield compared to sugar beet roots with intact crown (sample 1, Tab le 1). Removal of the crown mater ia l remain ing on sugar beet roots after scalping by the grower (sample 4, Tab le 1) resulted in a 1.9% increase in sucrose, a 3 .4% reduct ion in ni t ra te , a 7 . 3 % reduct ion in conductivity, and a 1 5 . 5 % reduct ion in yield compared to grower-scalped sugar beet roots (sample 3, T a b l e 1).

Sugar beet crown mater ia l accounted for 19 .4% of the total yield for the flailed roots and 1 5 . 5 % of the total yield for the grower-scalped roots (Tab le 1). This indicates tha t a considerable a m o u n t of the crown mater ia l is harvested and delivered to the factory. These da ta support those of Bugbee and Cole (2) concerning the percentage of sugar beet roots scalped to the lowest leaf scar.

Hobbis (5) observed an inverse relat ionship between sucrose content and ni t ra te g rade . Similar da ta were obta ined in this survey (Fig. 1). Flailed and grower-scalped sugar beet roots exhibited similar trends in sucrose reduct ion with ni t ra te g rade .

Figure 1.—Relationship between percent sucrose and brei nitrate grade in flailed and grower-scalped sugar beet roots. Numbers in parentheses indicate the humber of samples in each mean.


Cole et al. (4) showed that a positive relationship exists between soil ni t rate levels and percent crown tissue. A similar relationship was observed between brei ni t rate grade and percent crown (Fig. 2). This relationship indicates that the amount of crown mater ia l produced can be regulated by nitrogen management . Nitrogen management can result in an increase in sucrose content and a reduction in crown mater ia l .

Figure 2.—Relationship between percent crown and brei nitrate grade in flailed and grower-scalped sugar beet roots. Numbers in parentheses indicate the number of samples in each mean.

Sucrose content showed a decline as percent crown material increased in both flailed and grower-scalped sugar beet roots (Fig. 3 and 4). A highly significant negative correlation was observed between sucrose content and percent crown mater ia l . This relationship can be partially explained by the differential between sucrose level of root vs. crown mater ial , since the difference becomes larger as ni trogen increases. Nitrogen causes a reduction in sucrose and an increase in the amoun t of crown produced.

T h e data reported. above were obta ined from manual ly harvested roots where the t ap root and lateral roots remained primarily intact . However, sugar beet roots harvested mechanically rarely have lateral roots and the main tap root may be broken or cut by the lifter wheels. Therefore, differences in percentages of crown material would be expected when comparing manual ly harvested to mechanically harvested roots.

Crown material accounted for 2 0 . 5 % of the tonnage delivered to the piler a n d / o r factory station by the growers (Table 2). Removal of all the remaining crown mater ial resulted in a 1.2% increase in sucrose, a 5 . 3 %

Figure 3.—Relationship between percent sucrose and percent crown in flailed sugar beet roots.

Figure 4.—Relationship between percent sucrose and percent crown in grower-scalped sugar beet roots.

reduction in nitrate grade, and a 2.2% reduction in conductivity grade (Table 2) averaged over all locations.

Our results indicate that the factories are processing at least 15.5% of all crown material produced, which accounts for 20.5% of the total tonnage processed. Growers remove only 20% of the crown material produced. Assuming a 13.5 T/A yield, the grower could expect an additional 0.7 T/A from crown material if he flailed rather than scalped the beets. This would increase the amount of crown material being processed

1 3 5 V O L . 19, N o . 2 , O C T O B E R 1976

136 J O U R N A L O F T H E A . S . S . B . T

Table 2. Sucrose, ni trate, conductivity and percent crown of sugar beet roots selected from grower-trucks at selected piles a n d / o r factory locations in the Red River Valley.

†1 = Analysis of sugar beet roots as delivered by grower. 2 = Analysis of sugar beet roots with crown material removed to lowest leaf scar.

by the factory to 24 .6% of the total tonnage processed. T h e total tonnage processed by the factory from 50,000 acres would be increased from 675,000 to 710,000 tons. T h e addit ional tonnage would increase the slicing campaign 7 days for a 5,000 ton per day factory.

Zielke (6) showed that a ton of crown material contained 217 lbs of recoverable sucrose. Akeson, et al. (1) indicated that storage losses would be 10 to 15 percent less for flailed sugar beets compared to conventionally topped sugar beet roots. Wi th an increase in crown mater ial processed by the factory, a reduction in percent sucrose extraction would be expected. However, assuming the changes in yield and sucrose levels reported herein, sucrose extraction by the factory would have to d rop over 3% to offset the gain in addit ional sugar extracted from the crown mater ia l .

Sucrose extraction by the factory drops dur ing the lat ter par t of the processing campaign due to physical deteriorat ion of the roots, loss of sugar by respiration, and an increase in the amoun t of rot. Factory extraction should not d rop as rapidly or to the same levels for flailed beets compared to extraction from conventionally topped roots because respiration and rot t ing dur ing storage would be less (1 , 3).

VOL. 19, No. 2, OCTOBER 1976 137

Literature Cited (1) AKESON, W. R., S. D. FOX, and E. L. STOUT. 1974. Effect of topping

procedure on beet quality and storage losses. J. Am. Soc. Sugar Beet Technol. 18:125-135.

(2) BUGBEE, W. M. and D. F. COLE. 1976. Sugarbeet storage rot in the Red River Valley, 1974-75. J. Am. Soc. Sugar Beet Technol. 19:19-24.

(3) COLE, D. F. 1975. Effect of cultivar and mechanical damage on respiration and storability of sugarbeet roots. J. Am. Soc. Sugar Beet Technol. accepted.

(4) COLE, D. F., A. D. HALVORSON, G. P. HARTMAN.J . D. ETCHEVERS, and J. T. MORAGHAN. 1976. Effect of nitrogen and phosporus on percentage of crown tissue and quality of sugarbeets. North Dakota Farm Research. 33(5):26-28.

(5) HOBIS, J. K. 1973. Personal communication. (6) ZlELKE, R. C. 1973. Yield, quality, and sucrose recovery from sugarbeet root

and crown. J. Am. Soc. Sugar Beet Technol. 17:332-343.

A Revised Method for Determining Phosphate-Phosphorus Levels in

Sugar Beet Leaf Petioles1

G . E . V A R V E L , G . A . P E T E R S O N a n d F . N . A N D E R S O N 2


Knowledge of p lant nutr ient status dur ing the growing season can be valuable. Early detection of a deficiency sometimes allows it to be corrected that same growing season. Plant analysis also aids in p lanning the fertilization p rogram the following year.

Johnson and Ulrich (4)3 developed a test to determine the status of P in the growing sugar beet. They found that the amoun t of acetic acid soluble

in the leaf petiole mater ia l provided a reliable measure of P status. They have established that a concentrat ion of 750 p p m -P represents the "critical level."

Johnson and Ulrich determined the -P content with the phosphomolybdate method using SnCl2 as the reductant . Wi th this method , they have analyzed sugar beet petioles ranging in -P contents from 100 to 10,000 p p m . Al though their method is accurate and precise, it has one serious disadvantage: a lengthy oxidation with H 2 O 2 is needed to remove the color of dissolved organic compounds . T h e subsequent evaporation step to remove excess H 2 O 2 also causes the technique to be time consuming. This ra ther tedious method may have discouraged agronomists from making more frequent use of this technique.

T h e objectives of the experiment reported here were to determine if the SnCl2 reductant used by Johnson and Ulrich could be replaced with ascorbic acid and if this would allow elimination of the t ime consuming step of organic mat te r oxidation and subsequent evaporation of the excess H 2 O 2 .

Materials and Methods

Samples

Samples used in the me thod comparison experiments were sugar beet leaf petioles of the most recently ma tu red leaves. They were taken from plots in a P rate experiment in Scottsbluff County, Nebraska. T h e petioles were oven dried and g round to pass a 1 mm screen.

1Published with the approval of the Director as Paper No. 5125 of the Journal Series, Nebraska Agr. Exp. Sta., Lincoln.

2 Gradua te Assistant, Professor and Associate Professor, respectively. 3Numbers in parentheses refer to l i terature cited.

VOL. 19, No. 2, OCTOBER 1976 139

Extraction Extractions were m a d e by add ing 100 ml of Johnson and Ulrich acetic

acid ext rac tant to 0.4 g of p lant sample. These were shaken for 10 minutes on a wrist action shaker and filtered through a N O . 40 W h a t m a n paper . Extractions were m a d e in dupl icate . P- Determination

Two methods were used to determine the PO^n-P concentrat ion of the petioles. Method 1 was Johnson and Ulrich's procedure . This me thod was used with the SnCl2 reducing agent as described by Johnson and Ulrich and also with the ascorbic acid reducing agent .

Method 2, the proposed substitute, is described below: 1. After extraction, a 5 ml al iquot of the ext ractant was di luted to 20

ml with distilled water. (This replaces the 2 ml al iquot suggested by Johnson and Ulrich prior to the oxidation step).

2. A 2 ml al iquot was taken from this di luted sample and placed in a test tube .

3. Eight ml of the ascorbic acid working solution (reagents are listed in the next section) was then added to the test tube containing the 2 ml of the di luted sample .

4. After waiting 10 minutes for complete color development, the ab-sorbance was de te rmined at a X of 880 nm on a Beckman Spec-tronic 20 and the results compared to a s t andard curve with a range of 0.5 to 5 p p m P in solution.

Reagents for Method 2 (5) 1. Acid molybdate stock solution. Dissolve 60 g a m m o n i u m molyb

da te , (NH 4 ) 6Mo70244H 20, in 200 ml of distilled water. If necessary, heat to about 60°C unti l solution is clear and allow to cool. Dissolve 1.455 g of an t imony potassium tar t ra te in the molybdate solution. Add slowly 700 ml of concentra ted sulfuric acid. Cool and dilute to a final volume of 1000 ml . This solution may be blue, but will clear when di luted for use. Store in the dark unde r refrigeration.

2. Ascorbic acid stock solution. Dissolve 132 g of ascorbic acid in distilled water and dilute to a final volume of 1000 ml . Store in the dark under refrigeration.

3. Prepare a combined molybdate-ascorbic acid working solution each day by adding 25 ml of the acid molybdate stock solution to approximately 600 ml distilled water. T h e n add 10 ml of the ascorbic acid stock solution and br ing to a final volume of 1000 ml . Th i s a m o u n t will handle approximately 100 samples with s tandards and blanks.

Results and Discussion

Methods 1 and 2 are compared in Tab le 1 and Figure 1. T h e SnCI2

and the ascorbic acid reducing agents used with m e t h o d 1 gave essentially

140 J O U R N A L O F T H E A.S .S .B .T .

Table 1. Phosphate phosphorus content of sugar beet petioles as determined by methods 1 (Johnson and Ulrich) and 2 (proposed).

Methods

1_ 2

Reductant Reductant

Sample Ascorbic Ascorbic No. SnCl2 Acid Acid

Figure 1.—Comparison of SnCl2 and ascorbic acid reductants using Method 1. (John-son & Ulrich)

the same results. T h e coefficient of determinat ion of SnCl2 vs ascorbic acid in method 1 was r2 = 0.96. Consistency of the results of me thod 1 with both SnCl2 and ascorbic acid showed that either reductant was adequate . Alexander and Robertson (1,2), Murphy and Riley (6), John (3), Oman-war and Robertson (7), and W a t a n a b e and Olsen (8) have all shown that ascorbic acid is widely suited for different P determinat ion.

Figure 2.—Comparison of Method 1 (Johnson & Ulrich) and Method 2 (Proposed for determining levels in sugar beet petioles.

In view of the above results me thod 2 is proposed as a rep lacement for me thod 1. I t eliminates the t ime consuming oxidation and evaporat ion steps and still determines the levels accurately. T h e extraneous colors of the extracts do not affect the results when read at 880 nm as was previously shown by W a t a n a b e and Olsen (8).

By adopt ing me thod 2 the t ime consuming evaporat ion step is elimi-na ted and the procedure becomes much more rout ine . About 45-60 minutes can be saved per g roup (50 samples) and in addi t ion evaporat ion equ ipment is not needed. This saving may allow one individual to analyze almost twice as many samples in one day as was possible using me thod 1.

VOL. 19, No. 2, OCTOBER 1976 141

Results from method 2 were slightly lower in most cases than those in me thod 1 as shown in Tab le 1. However, the coefficient of de terminat ion of me thod 1 vs me thod 2 was r2 = 0.97. Figure 2 shows that the relat ionship between them is essentially 1:1 (b = 0.92). This means both methods are measur ing essentially the same thing. T h e slightly lower results with me thod 2 compared to me thod 1 may be due to the phosphates released from the organic mat te r dur ing the oxidation step in method 1. Since me thod 2 does not contain the oxidation step the organic phosphates are not de termined and hence the lower values.

1 4 0 J O U R N A L OF T H E A . S . S . B . X

Table 1. Phosphate phosphorus content of sugar beet petioles as determined by methods 1 (Johnson and Ulrich) and 2 (proposed).

Methods

1 2

Reductant Reductant

Sample Ascorbic Ascorbic No. SnCl2 Acid Acid

Figure 1.—Comparison of SnCl2 and ascorbic acid reductants using Method 1. (Johnson & Ulrich)

the same results. T h e coefficient of determinat ion of SnCl2 vs ascorbic acid in method 1 was r2 = 0 . 9 6 . Consistency of the results of method 1 with both SnCl2 and ascorbic acid showed that either reductan t was adequa te . Alexander and Robertson (1,2), Murphy and Riley (6), John (3), Oman-war and Robertson (7), and W a t a n a b e and Olsen (8) have all shown that ascorbic acid is widely suited for different P determinat ion.

VOL. 19, No. 2, OCTOBER 1976 141

Results from method 2 were slightly lower in most cases than those in me thod 1 as shown in T a b l e 1. However, the coefficient of de terminat ion of me thod 1 vs me thod 2 was r2 = 0.97. Figure 2 shows that the relationship between them is essentially 1:1 (b = 0.92). This means both methods are measur ing essentially the same thing. T h e slightly lower results with me thod 2 compared to me thod 1 may be due to the phosphates released from the organic ma t t e r dur ing the oxidation step in me thod 1. Since method 2 does not contain the oxidation step the organic phosphates are not de termined and hence the lower values.

Figure 2.—Comparison of Method 1 (Johnson & Ulrich) and Method 2 (Proposed for determining P 0 4

s -P levels in sugar beet petioles.

In view of the above results me thod 2 is proposed as a replacement for me thod 1. I t el iminates the t ime consuming oxidation and evaporat ion steps and still determines the levels accurately. T h e extraneous colors of the extracts do not affect the results when read at 880 nm as was previously shown by W a t a n a b e and Olsen (8).

By adopt ing me thod 2 the t ime consuming evaporat ion step is elimina ted a n d the procedure becomes m u c h more rout ine . About 45-60 minutes can be saved per g roup (50 samples) and in addi t ion evaporat ion equ ipment is not needed. This saving may allow one individual to analyze almost twice as many samples in one day as was possible using me thod 1.

142 JOURNAL OFTHE A. S.S.B.T

Literature Cited

(1) ALEXANDER, T. G. and J. A. ROBERTSON. 1968. Ascorbic acid as a reductant for total phosphorus determination in soils. Can. J. Soil Sci. 48:217-218.

(2) ALEXANDER. T. G. and J. A. ROBERTSON. 1970. Ascorbic acid as a reductant for inorganic phosphorus determination in Chang and Jackson fractionation procedure. Soil Sci. 110:361-362.

(3) JOHN, M. K. 1970. Colorimetric determination of phosphorus in soil and plant materials with ascorbic acid. Soil Science. 109:214-220.

(4) JOHNSON, C. M. and A. ULRICH. 1959. Analytical methods for use in plant analysis. Calif. Agr. Exp. Sta. Bull. 766:25-78.

(5) KNUDSEN, D. K. 1975. Recommended Chemical Soil Test Procedures for the North Central Region. North Central Regional Publications No. 221:16-19.

(6) MURPHY, J. a n d . P. RILEY. 1962. A modified single solution for the deter-mination of phosphate in natural waters. Anal. Chem. Acta. 27:31-36.

(7) OMANWAR, P. K. and J. A. ROBERTSON. 1969. Modification of the ascorbic acid method for determining phosphorus in dilute solutions. Can. J. Soil Sci. 49:259-261.

(8) WATANABE, F. S. and S. R. OLSEN, 1965. Test of an ascorbic acid method for determining P in water and sodium bicarbonate extracts from soil. Soil Sci. Soc. Amer. Proc. 29:677-678.

Effects of Weather Variables on the Yields of Sugar Beets Grown in an

Irrigated Rotation for Fifty Years

S . D U B E T Z a n d M . O O S T E R V E L D 1

Received for publication August 26, 1976

I n t r o d u c t i o n Forecasting of crop yields can be useful for optimizing m a n a g e m e n t of

a commodity and for providing a lead t ime to make necessary adjustments. Several workers have studied the relationships between sugar beet yields and various climatic factors. Kel'chevskaya (6)2 found tha t yields of sugar beets depend primarily on heat and moisture sufficiency dur ing the vegetative period. Because southern Alberta is semiarid, all sugar beets are grown under irr igation, and hence moisture insufficiency would not be ex-pected to be a major factor. Swift and Cleland (10) found that sugar beet yields were closely related to m e a n annua l t empera tu re bu t tha t there was less association with annua l precipi tat ion. B r u m m e r (2) reported that tem-pera ture was the most impor t an t climatic factor tha t affected sugar beet yields. Scott et al. (8) found that beet yields closely correlated with the amoun t of solar energy intercepted by the leaf canopy.

Relatively long-term yield and weather da ta are required to establish meaningful relationships tha t could be useful for predict ion in a par t icular area . A rotat ional exper iment at the Lethbr idge Research Station (lat. 49°42 'N, long. 112°47'W) has included sugar beets in the cropping se-quence since 1923 and thus provides half a century of such da ta . This pape r presents the yield-weather relationships for sugar beets in southern Alberta and establishes predictions that may be useful to the industry.

Mate r i a l s a n d Methods A 10-year rotat ion, designated as Rotat ion "U," was established on

irrigated land at the Lethbr idge Research Station in 1910. T h e details of the rotat ional exper iment were described by Dubetz (3). Sugar beets, one of the five crops grown in the rotat ion, were substituted for potatoes in 1923 and have been grown since. Half of the beet plot receives no fertilizer and the other half receives 100 l b / a c r e a m m o n i u m phosphate (11-48-0). Sugar beet yield da ta from the unfertilized plots were compiled from 1923 to 1974, and from the fertilized plots from 1933 to 1974.

1Soil Scientists, Research Station, Agriculture Canada, Lethbridge, Alberta, Canada T1J 4B1. 2Numbers in parentheses refer to literature cited.


Weather da ta have been recorded at the Station since 1902. T h e rela-tionship between yield and various climatic variables was studied to see which variables constrain yields the most in this region. T h e independent variables studied were:

(a) T i m e (advancing years); (b) Mean daily t empera ture (monthly and seasonal); (c) Tota l degree days (base 42°F or 6°C) from mean plant ing date

to mean harvest date ; (d) Mean daily hours of br ight sunshine from May 1 to August 31; (e) Tota l precipitat ion for May and June ; (f) Tota l precipitat ion 7 days before and 7 days after plant ing; (g) Plant ing da te ; (h) N u m b e r of frost-free days; (i) N u m b e r of days with temperatures above 28°F or - 2 . 2 ° C . Multiple regression analyses of sugar beet yields between these vari

ables were performed. T h e forward selection procedure was used to insert the independent variables one at a t ime into the regression equat ion. A 't-test' was performed for the variable most recently entered to indicate whether that variable had accounted for a significant amoun t of the variation over that removed by the previous variables in the regression.

To forecast yields several years in advance, addit ional calculations between yield and t ime were performed. First, the t ime trend was analyzed, using the linear and curvilinear regression methods , with t ime as the independent variable. After the t rend factors were accounted for, a detailed time-series analysis was performed, using the method of Jenkins and Wat ts (5). T h e homogeneity of the variance with t ime was tested, by decades, using Bartlett 's test (9). Then , the serial correlations and variance spect rum were computed (5), to establish whether there was any cycling in the yield da ta . Finally, a complete statistical forecasting model was assembled that gave the mean yields and the probabilities associated with a range of yields.

Results and Discussion A summary of some of the long-term (1902-1975) weather da ta for

southern Alberta appears in Tab le 1. T h e mult iple stepwise regression analysis of the da ta showed tha t tem

pera ture and time were the only factors that explained significant amounts of the variability in yield. T h e other climatic factors did not account for a significant a m o u n t of the residual variability. However, the n u m b e r of hours of bright sunshine and tempera ture was significantly correlated (r = 0.48).

T h e regression of annua l yields on advancing years (time) is shown in Figure 1. T h e regression coefficients and their levels of significance for the unfertilized and fertilized plots were 0.12 t on / ac r e /yea r (P < 0.01) and 0.10 ton / ac re /yea r (P < 0.025), respectively. Because these trends were

VOL. 19, No. 2, OCTOBER 1976

Table 1.—Summary of weather data (1902-1975 mean) for Lethbridge, Alberta. Mean

Precipitation temperature1 Sunshine2

Month (in.) (°F) (hr) January February March April

July August

October November December Total Mean 1The number of frost-free days and crop days (above 28°F) was 117 and 140. 267-year average.

significant, the regression line with t ime was used as the basis for further analysis.

Bartlett 's test (9) indicated no significant differences among the variances computed by decades; hence, further computa t ions based on a homogeneous variance were valid. Serial correlat ion and spectral analysis indicated that there was some minor cycling in the variance. However, none of the cycles explained enough of the variance to be useful for forecasting. Deviations were not significantly skewed from the t rend line.

It was decided from the preceding analyses to base forecasts on a projection of the regression line and to assign probabili t ies to a range of yields

YEARS Figure 1.—Regression of sugar beet yields in a 10-year irrigated crop rotation, with

and without fertilizer, on advancing years.

145

144 JOURNAL OF THE A.S .S .B.T.

Weather da ta have been recorded at the Station since 1902. T h e relationship between yield and various climatic variables was studied to see which variables constrain yields the most in this region. T h e independent variables studied were:

(a) T i m e (advancing years); (b) Mean daily t empera tu re (monthly and seasonal); (c) Tota l degree days (base 42°F or 6°C) from mean plant ing date

to mean harvest date; (d) Mean daily hours of br ight sunshine from May 1 to August 31 ; (e) Tota l precipitat ion for May and June ; (f) Tota l precipitat ion 7 days before and 7 days after plant ing; (g) Plant ing date ; (h) N u m b e r of frost-free days; (i) N u m b e r of days with temperatures above 28°F or - 2 . 2 ° C . Multiple regression analyses of sugar beet yields between these vari

ables were performed. T h e forward selection procedure was used to insert the independent variables one at a time into the regression equat ion. A 't-test' was performed for the variable most recently entered to indicate whether tha t variable h a d accounted for a significant amoun t of the variation over that removed by the previous variables in the regression.

To forecast yields several years in advance, addit ional calculations between yield and t ime were performed. First, the time t rend was analyzed, using the linear and curvilinear regression methods, with t ime as the independent variable. After the t rend factors were accounted for, a detailed time-series analysis was performed, using the method of Jenkins and Wat ts (5). T h e homogeneity of the variance with t ime was tested, by decades, using Bartlett 's test (9). T h e n , the serial correlations and variance spect rum were computed (5), to establish whether there was any cycling in the yield da ta . Finally, a complete statistical forecasting model was assembled that gave the mean yields and the probabilities associated with a range of yields.

Results and Discussion A summary of some of the long-term (1902-1975) weather data for

southern Alberta appears in T a b l e 1. T h e mult iple stepwise regression analysis of the da ta showed that tem

pera ture and t ime were the only factors that explained significant amounts of the variability in yield. T h e other climatic factors did not account for a significant a m o u n t of the residual variability. However, the n u m b e r of hours of bright sunshine and tempera ture was significantly correlated (r = 0.48).

T h e regression of annua l yields on advancing years (time) is shown in Figure 1. T h e regression coefficients and their levels of significance for the unfertilized and fertilized plots were 0.12 t on / ac r e /yea r (P < 0.01) and 0.10 t on / ac r e /yea r (P < 0.025), respectively. Because these trends were

V O L . 19, N o . 2 , O C T O B E R 1976

Table 1.—Summary of weather data (1902-1975 mean) for Lethbridge, Alberta.

Mean Precipitation temperature1 Sunshine2

Month (in.) (°F) (hr)

January February March April May June July August September October November December

Total

Mean 40.9 1 The number of frost-free days and crop days (above 28°F) was 117 and 140. 267-year average.

significant, the regression line with time was used as the basis for further analysis.

Bartlett 's test (9) indicated no significant differences among the variances computed by decades; hence, further computations based on a homogeneous variance were valid. Serial correlation and spectral analysis indicated that there was some minor cycling in the variance. However, none of the cycles explained enough of the variance to be useful for forecasting. Deviations were not significantly skewed from the trend line.

It was decided from the preceding analyses to base forecasts on a projection of the regression line and to assign probabilities to a range of yields

Figure 1.—Regression of sugar beet yields in a 10-year irrigated crop rotation, with and without fertilizer, on advancing years.

YEARS

145

1 4 6 JOURNAL OF THE A.S.S.B.T.

An a t t empt to predict the m e a n daily t empera tu re for a growing sea-son from the mean daily temperatures of previous months (October-De-cember, October-March, and October-May) proved unsuccessful because there was no dependence. T h e earliest that an improved forecast using tempera ture da ta from previous months can be m a d e is after the crop is p lanted. T h e yield equations and s tandard deviations that were calculated by months after the crop was p lanted are shown in T a b l e 3.

Incorporat ion of May or May plus J u n e t empera tu re da t a into the prediction equat ion after the crop was p lanted resulted in a significant reduct ion in the magn i tude of the s tandard deviation of the forecast. Ad-dit ion of July, August, and September temperatures did not improve the yield forecasts significantly, which suggests tha t the tempera tures du r ing these months in this area are near opt imal for sugar beets. Al though it was not statistically significant, the regression coefficient for the July t empera -ture variable was negative. This suggests that perhaps the mean July tem-pera ture might be slightly high for opt imal product ion.

T h e significant and positive regression coefficient of 0.1 t o n / acre /year probably resulted from improved soil fertility (3), use of bet ter adap ted varieties, and improved managemen t that occurred with t ime.

based on the normal distr ibution. T h e equat ion used for forecasting yields was:

where Y = yield in tons per acre tha t corresponds to a specific year; a = intercept; b = slope; year = calendar year; a = s tandard deviation of the regression line; and e = a s tandardized variate with a m e a n of 0 a n d a s tandard deviation of 1.

T h e equat ion was used to predict the yield for 1975 at various p robability levels, and these are shown in Tab le 2.

T h e best forecast yields for 1975, using this equat ion, were 19.67 and 21.84 tons /acre for the unfertilized and fertilized plots in this rotat ion. T h e actual yields were 19.26 a n d 22.30 tons /acre , respectively, from the two plots. T h e above predictions were calculated without adjustment for any of the weather parameters . T h e calculated regression coefficients on tempera ture after the t ime t rend was removed for the unfertilized and fertilized plots were 0.72 (P < 0.025) and 1.02 (P < 0.005) t o n / a c r e / ° F .

Table 2.—The probability that a given yield would not be equaled or exceeded in 1975.

Prob- Yield (tons/acre) ability

level (96) Unfertilized Fertilized Expression

Table S.—Yield equations and standard deviations (a) calculated for various times.


These results agree with those of others (2, 5, 6, 9), who found that t empera ture was the most impor tan t climatic factor affecting sugar beet yields. Swift and Cleland (9) used m e a n temperatures of several months that preceded the p lant ing da te in their forecast of yields. However, we found no discernible dependence of growing season temperatures on temperatures of months that preceded the mon th of plant ing. After the crop was planted, incorporat ion of May or May plus J u n e tempera tures into the prediction equat ion reduced the size of the s tandard deviation of the forecast. T h e s tandard deviation would probably be further reduced if an average yield for several sites is to be predicted (6).

Because rainfall was not significantly related with yield, irrigation as practiced in this rotat ion apparent ly provided adequa te moisture for sugar beets. Yields were also unaffected by the amoun t of precipi tat ion that occurred immediately before and after p lant ing. This may be explained in par t by the fact that fall irrigation was usually pract iced, the soil has a relatively fine texture, and the rate of seeding was usually sufficiently high to ensure a good stand.

T h e average plant ing da te of sugar beets on this rotat ion was April 29 11 days, and yields were not significantly affected by this variable. An

derson et al. (1) reported that sugar beet yields at Lethbr idge were not significantly affected when the crop was p lanted between April 20 and May 10.

S u m m a r y An equat ion for predict ing sugar beet yields based on regression

analysis of 50 years of yield da ta from one site in southern Alberta is presented. Under irrigation, t empera tu re was found to be the only climatic variable that significantly affected sugar beet yields. Tempera tu res dur ing a growing season were not dependen t on those of previous months . Incorporat ion of May and J u n e temperatures of the cur ren t year into the equation reduced the size of the s tandard deviation of the forecast. T h e precision of the predict ion would probably be further improved if da ta from addit ional sites were incorporated.

Literature Cited

(1) ANDERSON, D. T., S. DUBETZ, and G. C. RUSSELL. 1958. Studies on transplanting sugar beets in southern Alberta. Proc. Am. Soc. Sugar Beet Technol. 10: 150-155.

(2) BRUMMER, V. 1961. On the relations between sugar beet yields and certain climatic factors in Finland. A statistical study and some cultivation technique applications [in Finnish]. Suom. Maataloust. Seur. Julk. 98: 1-180.

(3) DUBETZ, S. 1954. The fertility balance in a ten-year sugar beet rotation after forty-two years of cropping. Proc. Am. Soc. Sugar Beet Technol. 8: 81-85.

VOL. 19, No. 2, OCTOBER 1976 149

(4) HILL, K. W. 1951. Effects of forty years of cropping under irrigation. Sci. Agr. 31: 349-357.

(5) JENKINS, G. M. and D. G. WATTS. 1968. Spectral analysis and its application. Holden-Day, San Francisco, Calif. 525 pp.

(6) KELCHEVSKAYA, L. S. 1965. Complex estimate of the heat and moisture sufficiency of the vegetative period of sugar beets. Treatises Cent. Forecasting Inst. 1965(140): 97-104. (Transl. from Russian.)

(7) KRUMBIEGEL, DIETMAR. 1972. The effect of meteorological conditions on the level and stability of crop yields [German, English summary]. Arch. Acker-Pflanzenbau Bodenkd. 16: 771-777.

(8) SCOTT, R. K., S. D. ENGLISH, D. W. WOOD, and M. H. UNSWORTH. 1973. The yield of sugar beet in relation to weather and length of growing season. J. Agric. Sci. 81: 339-347.

(9) STEEL, R. G. D. and J. H. TORRIE. 1960. Principles and procedures of statistics. McGraw-Hill Book Company, Inc., Toronto. 481 pp.

(10) SWIFT, EDWARD L. and FRANK A. CLELAND. 1946. The effect of climate on sugar beet yields in western Montana. Proc. Am, Soc. Sugar Beet Technol. 4: 135-140.

Tests with Fungicides to Control Rhizoctonia Crown Rot of Sugarbeet1 2

C . L . S C H N E I D E R , H . S . P O T T E R a n d D . L . R E I C H A R D 3


Crown rot disease, incited by the soil-borne fungus, Rhizoctonia solani Kuehn, appreciably reduces stands of sugarbeet {Beta vulgaris) each year. Control measures presently recommended to growers consist mainly of cultural methods, such as crop rotat ion. Other means of control to complement cultural control methods, including the use of fungicides, have been investigated ( 1 , 2 , 6)4. We have reported on the results of screening tests with a large n u m b e r of fungicides to control crown rot (4, 5, 6). In these tests the following fungicides, applied as crown sprays, significantly reduced crown rot incidence: 5,6-dihydro-2-methyl-l ,4-oxathiin-3-car-boxanilide, carboxin; methyl l-(butylcarbamoyl)-2-benzimidizolecarba-mate , benomyl; tr iphenyltin hydroxide, T P T H ; pentachloroni t robenzene, PCNB; dimethyl [ l ,2-phenylene)bis (iminocarbonothioyl)] =bis [carba-mate] , th iophana te methyl; and tetrachloroisophthalonitr i le, chloro-thalonil .

In 1972, 1973, and 1974 we conducted addit ional field tests with most of the above fungicides at rates lower than had previously been used. We also tested addit ional fungicides, and investigated the use of foam with fungicide sprays. T h e results of these tests are presented here.

Mate r ia l s a n d Methods Screening Tests

In 1972, 1973 and 1974 we tested 10 fungicides, at varied rates, for effectiveness as crown sprays in plots artificially infested with a crown and root rot t ing isolate of R. solani. Some of the t rea tments were included in each of the three tests and others were included in one.

T h e fungicides evaluated were: bis (bimethylthiocarbamoyl) disulfide, th i ram; l ,4-dichloro-2,5-dimethoxybenzene, chloroneb; carboxin; benomyl; 2,2,-methylenebis [3,4,6-trichlorophenol], hexachlorophene; PCNB; chlorothalonil; T P T H ; and carboxin + th i ram.

'Cooperative investigations of Agricultural Research Service, U.S. Depar tment of Agriculture and the Michigan Agricultural Experiment Station, East Lansing, Michigan. Publication approved by the director, Michigan Agricultural Experiment Station as Journal Article No. 7635.

T h i s report includes the current status of research on pest control. It does not contain recommendations for use of pesticides nor does it imply that uses discussed have been registered.

'P lan t Pathologist, Agricultural Research Service. U.S. Depar tment of Agriculture, East Lansing, MI 48823; Professor, Depar tment of Botany and Plant Pathology, Michigan State University, East Lansing, MI 48824; and Agricultural Engineer, Agricultural Research Service, Ohio Agricultural Research and Development Center, Wooster, OH 44691.

'Numbers in parentheses refer to l i terature cited.

VOL. 19, No. 2, OCTOBER 1976 151

The tests were located on the Botany Farm at the Michigan Agricultural Experiment Station, East Lansing. The preceeding crop in each year had been maize. The plots of commercial sugarbeet variety U.S. H20 were arranged in randomized blocks. Plot length in 1972 and 1973 was 6.1 m and in 1974 was 5 .0m.

T h e plots were infested with dry whole sorghum grain inoculum of R. solani after seedling emergence. T h e inoculum was drilled 12 mm deep and at a distance of 7 cm on each side of a plant row. In 1972, 1973, and 1974, respectively, plots were infested 33, 26 and 40 days after planting and at rates totaling 23.6, 30.5 and 11.5 c c / m of row. T h e Rhizoctonia isolate used was the same as that used previously (4, 5, 6).

We applied the fungicide treatments in 561.2 1 wa te r /ha (60 gal /acre) with a hand-operated, C02-act ivated sprayer equipped with a single nozzle. T h e spray was directed into the crowns and at the bases of the plants as the operator walked along the row. T h e spray application dates were 6 July, 22 July and 16 August in 1972; 5 July, 17 July, and 3 August in 1973; and 11 July, 29 July, and 23 August in 1974. T h e application rate of each treatment, expressed as active ingredient/acre, is indicated in the Results section and in the appropriate table.

Stand counts were made at time of inoculation. Disease incidence, expressed as the number of plants with crown rot symptoms divided by the number of plants inoculated, was determined at harvest.

Test of fungicides with foam When a spray containing foam is directed into the lower foliage of a

sugarbeet plant, the resultant foam deposit slowly slides down blades and petioles and collects at the base of the plant where, presumably, crown rot infection commonly occurs. Accordingly we conducted a test with four fungicides to determine the effect of foam additive on their efficacy. T h e fungicide treatments included benomyl, carboxin, chlorothalonil, and T P T H . T h e foaming agent was a commercially available amphoteric surfactant containing the partial sodium salt of N-lauryl B-iminodipropionic acid.

T h e experiment was located in the same field as the 1974 screening test with the same variety and the same plot inoculation techniques. There were four main plots of each fungicide treatment arranged in four randomized blocks. Each main plot comprised two rows, 10.1 m long. One row in each main plot was sprayed with fungicide + foam, whereas the adjoining plot was sprayed with the same fungicide alone.

Treatments were applied with experimental equipment developed at the ARS Agricultural Engineering Laboratory, OARDC, Wooster, Ohio. The sprayer, mounted on the 3-point hitch at the rear of a tractor, applied the foam and the nonfoam treatments at 280.6 1 wa te r /ha (30 gal /acre) from the same tank containing water, fungicide and foaming agent. A nozzle positioned directly over each of the paired plots directed a spray downward in a band 20 cm wide. T h e foaming agent was applied at 2.1

152 JOURNAL OFTHE A.S.S.B.T

1/ha (0.225 ga l /acre) with a foam generator that mixed the fungicide-foaming agent solution with air. T h e foam was discharged downward from a special nozzle in a conical pa t te rn of small globs with an expansion rat io of about 15 to 1. Spray applicat ion dates were 9 and 17 July. Disease incidence was determined on 24 October .

Results Screening tests

In each test, the first symptoms of crown rot appeared within 14-19 days after applicat ion of inoculum. Incipient symptoms appeared throughout the growing season. Plants that had died from crown rot were readily identified at harvest by their persistent withered foliage.

T h e general level of disease incidence varied considerably from year-to-year. Disease incidence in control plots in 1972, 1973, and 1974 was 19.7, 89.8, and 23.3 percent respectively. These wide variations may be associated with differences in soil moisture tha t prevailed shortly after inoculum applicat ion. In 1972 and 1974, drought-l ike conditions prevailed at that time; in 1973, soil moisture appeared to be normal and presumably more favorable for init iation of infection. Differences in disease incidence level among the three tests may also be associated with differences in the quant i ty of inoculum applied each year.

In each screening test, there were t rea tments tha t reduced crown rot incidence significantly below that of the control (Table 1), including: benomyl (420 g / h a ) , carboxin (3.36 kg), chlorothalonil (1.68 kg), T P T H (332.8 g) and PCNB (2.24 kg), as well as carboxin + th i ram (840.6 g + 840.6 g). Chloroneb, hexachlorophene, and th i ram did not significantly reduce disease incidence. The re was no evidence of phytotoxicity associated with any of the t reatments .

Test of fungicides with foam Three of the four entries — carboxin (2.24 k g / h a ) , chlorothalonil

(1.68 kg), and T P T H (332.8 g), significantly reduced crown rot, whereas benomyl (282.2 g) d id not (Table 2). In comparison to the control , carboxin with foam significantly reduced crown rot, whereas carboxin alone did not . Foam additive had no significant effect on efficacy of the other fungicides. In the analysis of variance, F values for foam and foam x fungicide interaction were not statistically significant.

Discussion T h e results of our tests confirm previous findings on the ability of

topical applications of benomyl, chlorothalonil , carboxin, fentin chloride, and PCNB to reduce crown rot. T h e results with T P T H also confirm observations by Finkner et al. (3) on the reduct ion of crown rot in plots sprayed with organo-t in fungicides to control Cercospora leaf spot.

It should be emphasized that T P T H significantly reduced crown rot

18.8 b4 87.1 bc 45.0 b 14.4 ab - 16.5 a

83.0 bc 11.4ab 82.6 bc

28.2 ab 75.3 ab

3.4 a 11.8ab 3.6 a - 42.3 b

76.1 abc 30.7 ab

14.8 ab 84.1 be 11.7 a 12.8 ab

64.6 a 13.2 ab

'Means of 5 plots, each 6.1m long. 'Means of 8 plots, each 6.1m long. •Means of 6 plots, each 5.0 m long. 4Entries in the same year followed by the same letteT do not differ significantly at the 5% level.

Table 2.—Efficacy of four fungicidal crown sprays, with and without foam, in reduction of Rhizoctonia crown rot of sugarbeet.

Crown rot incidence (%)

Fungicide and a.i. rate/ha and (acre)

Benomyl50W,280.2g(4oz)

Carboxin75W,2.24kg(21b)

Chlorothalonil 75W, 1.68 kg (1.5 lb)

TPTH47.5W, 332.8g(4.75oz)

Control

Foam treatment mean (control not included)

1Means of four plots, 10.1 mlong. 2Entries followed by same letter do not differ significantly at the 5% level.

JOU

RN

AL

O

FT

HE

A

.S.S

.B.T

.

VOL. 19, No. 2, OCTOBER 1976 155

when applied at a rate within the limits approved for leaf spot control; car-boxin, chlorothalonil, and PCNB reduced the disease when applied at rates recommended by their suppliers. Benomyl, conversely was effective only when applied at rates above the 282 g / h a (4 oz/acre) limit approved for leaf spot control.

Our tests demonstrated reduction of crown rot with the combination treatment: carboxin + thiram. T h e activity of the carboxin component against Rhizoctonia has already been shown (4, 5). Th i ram alone in the 1972 test did not significantly reduce crown rot.

T h e results of the tests were variable and inconsistent in that treat-ments that significantly reduced crown rot in some trials failed to do so in others. On the basis of these trials, recommendation of any of the de-scribed treatments as a control measure is not yet warranted. The inconsis-tent results, on the other hand, indicate a need for more effective ways of applying chemicals that have the potential for controlling crown rot. T h e use of improved spraying systems and spray adjuvants may be advan-tageous. Although the foam additive that we tested failed to significantly improve the efficacy of all the fungicide treatments, it did not, on the other hand, impair the efficacy of any. In addition to foaming agent, there are other materials to be considered as aids in the application of sprays for crown rot control, including drift retardants and sticker-spreaders.

Summary In a series of tests in field plots artificially infested with Rhizoctonia

solani, fungicides were sprayed at various rates into the crowns and at the bases of the plants. Fungicides showing potential for reducing crown rot incidence included: benomyl (420 g /ha ) , carboxin (1.68 kg), chlorothalo-nil (1.68 kg), T P T H (332.8 g), PCNB (2.24 kg), and carboxin + thiram (840.6 g + 840.6 g). Inconsistent and variable control with most of the treatments indicates a need for improved methods of application. A foam additive slightly increased the efficacy of one of four fungicidal sprays with which it was tested.


Literature Cited

(1) AFANASIEV, M. M. and D. E. BALDRIDGE. 1968. Selection for resistance and chemical control of Rhizoctonia root rot disease of sugarbeets. J. Am. Soc. Sugar Beet Technol. 15: 150-158.

(2) AFANASIEV, M. M. and H. E. MORRIS. 1952. Resistance and soil treatments for control of Rhizoctonia of sugar beet. Proc. Am. Soc. Sugar Beet Technol. 14: 562-567.

(3) FINKNER, R. E., D. E. FARUS, and L. CALPOUZOS. 1966. Evaluation of fungi-cides for the control of Cercospora leaf spot of sugarbeets. J. Am. Soc. Sugar Beet Technol. 14: 232-237.

(4) SCHNEIDER, C. L. and H. S. POTTER. 1969. In Fungicide and Nematicide Tests 25: 98-99. Amer. Phytopathol. Soc.

(5) SCHNEIDER, C. L. and H. S. POTTER. 1970. In Fungicide and Nematicide Tests 26: 102-103. Amer. Phytopathol. Soc.

(6) SCHNEIDER, C. L. and H. S. POTTER. 1974. Tests with soil treatments and crown sprays to control Rhizoctonia crown and root rot of sugarbeet. J. Am. Soc. Sugar Beet Technol. 18: 45-52.

Effect of Fungus Infection on Respiration and Reducing Sugar Accumulation

of Sugarbeet Roots and Use of Fungicides to Reduce Infection1

D. L. MUMFORD a n d R. E . WYSE2

Received for publication August 9, 1976

In recent years, the covering of sugarbeet storage piles has greatly reduced losses due to freezing and thawing. This practice, however, has not reduced losses from fungus deterioration of stored roots. In fact, pile covering often provides a favorable environment for fungus growth.

T h e objective of this research was to obtain information on the effect of fungus infection on sugarbeet roots and to determine whether fungicides would be an effective control measure.

Materials and Methods T h e fungi used in these studies were isolates of Penicillium and

Botrytis obtained from infected beet roots from a storage pile at Quincy, Washington. To study the effect of infection by these fungi, a method was developed to obtain predictable amounts of infection on roots. Roots were injured, using a small 2.5x5x15 cm board pierced by 12 small nails within a circular area 3 cm in diameter and protruding 3 mm through the board. T h e nail points were pressed against the root surface and then rotated to produce a circular injury 3 cm in diameter and 3 mm deep. T h e injured area was inoculated, and the roots were stored under humidity (98%) and temperature (15°C) conditions favorable for infection. Fungus inoculum was prepared from colonies grown in petri dishes on potato dextrose agar (PDA). T h e agar disk with the fungus culture was chopped in a blender for a very brief period of time so as not to liquify the agar. T h e agar was then separated from the mycelium and spores by straining through cheesecloth.

Respiration rates were determined using a flow-through system. Car-bon dioxide concentrations in the air stream were determined with an automated switching system and an infrared analyzer. T h e amount of

1Cooperative Investigations of the Agricultural Research Service, U.S. Department of Agriculture; the Beet Sugar Development Foundation; and the Utah State Agricultural Experiment Station. Approved as Journal Paper No. 2103. Utah Agricultural Experiment Station, Logan, Utah 84322.

2Plant Pathologist and Plant Physiologist, respectively, Agricultural Research Service, U.S. Depart-ment of Agriculture, Crops Research Laboratory, Utah State University, Logan, Utah 84322.

Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by U.S.D.A., nor does it imply its approval to the exclusion of other products that may also be suitable.


reducing sugar accumula ted was de termined using dinitrosalicylic acid on leaded juice ( l ) . 3 Measurements of respiration ra te and reducing sugars were m a d e three weeks after roots were inoculated, dur ing which t ime the roots were held at 15°C.

Fungicides were initially evaluated by measur ing inhibit ion of fungus growth on an agar med ium. Disks of filter paper sa tura ted with a par t icu-lar concentrat ion of fungicide were positioned equidistantly a round the outer edge of a petri dish containing 20 ml of PDA. T h e fungus was seeded in the center and allowed to grow toward the filter paper disks (Fig. 1). Inhibit ion of growth was measured after two to three days.

Superior fungicides selected by this me thod were tested directly on roots. Injured roots were inoculated and then t reated with spray ap-plications of 100, 250, 500, 750, 1000, and 1500 p p m of fungicide. Evalua-tion of fungicide effectiveness was based on visual observation of fungus growth and measurement of root respiration ra te .

Figure 1.—Inhibition of Botrytis growth on agar by different concentrations of fun-gicide.

Results Effect of fungus infection on root respiration rate and reducing sugar

accumulation. Respirat ion ra te increased as the percentage of surface area infected increased, as shown in Fig. 2. A correlation of .93 was obta ined between these two factors. Roots with 2 0 % of their surface area infected with Botrytis h a d a 100% higher respiration ra te than injured bu t un in-fected controls. Similar results occurred with roots infected with Penicil-


VOL. 19, No. 2, OCTOBER 1976

Percent Surface Area Infected Figure 2.—Relationship of root surface area infected to increase in respiration rate.

Hum. Injured but noninoculated roots, which had little or no fungus in-fection, had less than a 5% increase in respiration rate.

T h e results relating amount of reducing sugars accumulated with per-centage of root surface area infected are presented in Fig. 3. When 1 5 % of the root surface area was infected, there was a three-fold increase in reducing sugars compared to uninfected roots. This increase was highest in

Figure 3.—Relationship of root surface area infected to increase in reducing sugars accumulated.

159


the immedia te area of infection. However, measurements of reducing sugar content of tissue from healthy, mildly infected, and severely infected roots indicated that the increase could occur th roughout the root (Tab le 1). In severely infected roots, the reducing sugar content is greatly in-creased in tissue several centimeters away from the infection site, as shown in Tab le 1.

T a b l e 1 . R e d u c i n g s u g a r c o n t e n t o f a p p a r e n t l y h e a l t h y t i ssue f r o m i n f e c t e d roots .

T i s s u e R e d u c i n g S u g a r R o o t C o n d i t i o n L o c a t i o n ( m g / g m F r e s h W t . )

Healthy 2 cm from surface 1.9 Center of root 1.9

Mildly Infected 2 cm from infected area1 7.4 Center of root 1.8

Severely infected 2 cm from infected area 15.0 Center of root 13.6

1All tissue showing discoloration symptoms of infection was removed before sampling.

Evaluation of fungicides in reducing infection of sugar beet roots by Penicillium and Botrytis. Sixteen fungicides (Table 2) were evaluated by the agar plate method . Of the four fungicides causing the greatest inhibit ion of fungus growth (Table 3), benomyl and thiabendazole were selected for testing on sugarbeet roots.

T a b l e 2. F u n g i c i d e s tested as a c o n t r o l for Penicillium a n d Botrytis.

Benlate (benomyl) OAC 5 Botran OAC 258 Bravo 6F Pyrocatechol Dowicide A Steri-Seal " D " (SOPP) Dowicide 1 Steri-Seal D-D-400 Fisons NCI6598 Terrac lor (PCNB) Hydrogen peroxide Terrazole Mertect (thiabendazole) Zinc Omadine

T a b l e 3 . I n h i b i t i o n o f f u n g u s g r o w t h o n a g a r m e d i u m b y f o u r f u n g i c i d e s .

I n h i b i t i o n i n p e r c e n t a g e o f

c o n t r o l for e a c h c o n c e n t r a t i o n

F u n g u s F u n g i c i d e lOOppm* l , 0 0 0 p p m 1 0 , 0 0 0 p p m

Botrytis Benomyl 44 51 56 Thiabendazole 27 54 57 SOPP 0 23 54 PCNB 13 18 26

Penicillium Benomyl 21 31 49 Thiabendazole 0 27 41 SOPP 0 14 S3 PCNB 0 7 9

*Concentrations were adjusted to comparable amounts of active ingredient for each fungicide.

V O L . 19, N o . 2, O C T O B E R 1976 161

Figure 4.—Transverse and surface views of injured roots inoculated with Penicil-lium. No infection is present on root treated with spray application of 500 ppm thia-bendazole.

Eased on visual observation of fungus growth (Fig. 4) and measure-ment of root respiration rate, complete control of infection was obtained by a spray application of either fungicide at a concentration of 500 p p m . A spray application of 500 ppm similar to the one we used was estimated by Merck and Company to leave about 0.5 p p m fungicide on an average (0.45 kg) root. Fungus growth on roots treated with concentrations as low as 100 ppm was greatly reduced compared to untreated roots.

Our observations indicated that injury was essential for fungus in-fection. Many uninjured roots were inoculated, but none became infected. It was also noted that inoculation was necessary to obtain high levels of in-fection when using washed roots but was not necessary when using un-washed roots. This indicated an abundance of inoculum present in soil adhering to roots, as they would normally go into storage.

Conclusions T h e results of these experiments indicate that within a period of one

month the respiration rate of stored sugarbeet roots will double if approxi-mately 2 0 % of their surface area is infected by fungi. T h e data also indi-


cate tha t there will be over a three-fold increase in reducing sugars with similar amounts of infection.

A spray applicat ion of benonyl, or thiabendazole, at a concentrat ion of 500 p p m will prevent infection by Pentcillium and Botrytis of injured sugarbeet roots dur ing the initial storage period.

Root injury before storage is probably the most significant factor de-termining the extent of fungus infection. The re is probably sufficient fun-gus inoculum in soil adher ing to roots to initiate infection when conditions are favorable for fungus growth dur ing root storage.

Literature Cited

(1) MILLER, G. L. 1959. Use of dinitrosalicylic acid reagent for determination of reducing sugar. Anal. Chem. 31:426.

Sugarbeet Yield and Theoretical Photosynthesis in the Northern Great Plains1

E. J. DOERING2

Received for publication December 5, 1975

Sugarbeets have been grown for several decades in the Red River Valley of North Dakota without irrigation and in the Yellowstone Valley of eastern Montana with irrigation. Part of the sugarbeet's acceptance by farmers is attributable to the fact that, unlike most an-nual plants, it can recover after being damaged by hail or some other adverse weather condition and still produce a partial yield. In fact, Afanasieve (I)3 showed that the midseason removal of 50% of the leaves in Montana reduced root yields by about 10% and sugar yields by about 4%. In addition, sugarbeets grow well in northern latitudes and are a high-value crop under favorable growing conditions. As new lands are brought under irrigation as part of the Garrison Diver-sion Project in North Dakota, growers will likely consider the growing of sugarbeets on their irrigated lands.

However, in spite of the sugarbeet's general acceptance by farm-ers, field yields for irrigated sugarbeets have been relatively low at the Carrington Irrigation Branch Station of the North Dakota Agricul-tural Experiment Station, Carrington, North Dakota. Between 1962 and 1969, sugarbeet yields averaged only 12.2 tons/acre and ranged from 8.0 to 18.4 tons/acre.4 Sucrose content averaged 16.9% and varied less from year to year than root yields. Compared with the 44-year average yield of 10.2 tons/acre and 16.0% sucrose, without irri-gation, in Grand Forks County, North Dakota,5 these yields with irriga-tion are indeed mediocre.

Large variability of yield with years suggests climatic influences on yield. Climate affects yield several ways. For example, Radke and Bauer (9), in laboratory studies, found that the optimum soil tempera-ture for sugarbeet germination was between 77° and 95°F. Shaw and Buechele (10) found that soil ridges were warmer than fiat surfaces for several hours during the day, and Benz, et al. (3) reported that a clear plastic germination cap over the seed row increased soil tempera-

1Contribution from Soil, Water, and Air Sciences, North Central Region, Agricultural Re-search Service, USDA.

2Agricultural Engineer, Northern Great Plains Research Center, P.O. Box 459, Mandan, North Dakota 58554.

3Numbers in parentheses refer to literature cited. 4 Personal communication from Howard M.Olson, Supt., Carrington Irrigation Branch Station. 5Personal communication from Russell A. Steen, Research Agriculturist, American Crystal

Sugar Co., East Grand Eorks, Minn. 56721.


t u r e by 5° to 11 °F in t h e t o p 3 i n c h e s o f soil d u r i n g t h e las t w e e k of May. Even so, soil t e m p e r a t u r e s in N o r t h D a k o t a s e l d o m rise above 77°F for m a n y h o u r s o f t h e day d u r i n g ear ly s p r i n g . T h e r e f o r e , s t a n d e s t a b l i s h m e n t is a p r o b l e m usual ly o v e r c o m e by h i g h s e e d i n g ra tes a n d s u b s e q u e n t t h i n n i n g . Swift a n d Cle l l and (11) s ta ted tha t suga r -beets g rew well w h e r e the s u m m e r i s o t h e r m was a b o u t 70°F. T h e long-t e r m a v e r a g e air t e m p e r a t u r e s a t C a r r i n g t o n a r e 62.4° , 69.4°, 67.1° a n d 56.1°F for J u n e , J u l y , A u g u s t , a n d S e p t e m b e r , respect ively (16).

L a b o r a t o r y e x p e r i m e n t s by Ul r i ch (12, 13) have s h o w n tha t low n ight t e m p e r a t u r e s p r o d u c e d g r e a t e r suc rose c o n c e n t r a t i o n s a n d less t o p g r o w t h , a n d t h a t suc rose p r o d u c t i o n was m a x i m u m with 8 h o u r s of sun l igh t p e r day a n d a n i g h t t e m p e r a t u r e of 63°F. H o w e v e r , for 13.5-hr . day l eng ths , suc rose c o n c e n t r a t i o n s i nc reased as n i g h t - t i m e t e m p e r a t u r e s d e c r e a s e d t o 39°F. Conve r se ly , R a d k e a n d B a u e r (9) f o u n d t h a t suc rose c o n t e n t i nc rea sed f r o m 1 0 . 5 % to o v e r 1 3 % as con-s tan t r o o t t e m p e r a t u r e r a n g e d f r o m 66° to 99°F for a 1 5-hr . day l eng th in t h e l abo ra to ry , a n d t h a t sucrose yield was h igh for c o n s t a n t r o o t t e m p e r a t u r e s b e t w e e n 64° a n d 90°F. A f ie ld s tudy (14) on t h e effect o f c l imate o n s u g a r b e e t s g r o w n u n d e r s t a n d a r d i z e d c o n d i t i o n s ind i -ca ted t h a t a n i g h t t e m p e r a t u r e of a b o u t 41° d u r i n g t h e last 4 weeks be fo re ha rves t c a u s e d t h e h ighes t suc rose c o n c e n t r a t i o n s b u t tota l sucrose p r o d u c t i o n was n o t r e p o r t e d .

We c o n d u c t e d t he fol lowing e x p e r i m e n t s t o d e t e r m i n e t h e rela-tive significance of c l imate a n d e n d o g e n o u s factors on ear ly season s u g a r b e e t g r o w t h a n d to eva lua te t h e effect o f year ly cl imatic d i f fer -ences on s u g a r b e e t yield a n d theo re t i ca l p h o t o s y n t h e s i s i n N o r t h Dako ta .

Materials and M e t h o d s S u g a r b e e t s w e r e g r o w n in we11-irrigated f ie ld plots a t t h e C a r r i n g -

ton I r r i g a t i o n B r a n c h Sta t ion , C a r r i n g t o n , N o r t h D a k o t a o n n o n s a l i n e , ca l ca reous H e i m d a l loam (Udic Haploboroll). Resul ts f rom b o t h repl ica-ted a n d n o n r e p l i c a t e d e x p e r i m e n t s a r e i n c l u d e d . S u g a r b e e t cu l t ivar H H - 1 0 6 was p l a n t e d in 24-in. r ows a n d t h i n n e d to a p o p u l a t i o n of 26 ,000 p lan t / ac re for all e x p e r i m e n t s . I r r i g a t i o n w a t e r was a p p l i e d in su r face fu r rows the f i rs t y e a r (1966) a n d with a r o t a t i n g - b o o m type s p r i n k l e r i r r i g a t o r (4) in 1967, 1968 a n d 1969.

T h e basic e x p e r i m e n t was a r a n d o m i z e d block des ign us ing yea r s a s t r e a t m e n t s wi th t h r e e rep l i ca t ions . F o r this e x p e r i m e n t , s u g a r b e e t s w e r e g r o w n o n t h e s a m e plots d u r i n g f o u r consecu t ive yea r s ( 1966 to 1969). S u p p o r t i n g e x p e r i m e n t s i n c l u d e d a var ie ty of d i f f e r en t t r ea t -m e n t s each yea r bu t t r e a t m e n t d i f f e rences w e r e no t significant d u r i n g any year . H e n c e , t hese t r e a t m e n t yields a r e u sed a s c o m p o n e n t s o f

6Holly Sugar Corporation, Sidney, Montana. (Trade and company names are given for the reader's benefit and do not imply endorsement or preferential treatment of any product by the U.S. Dept. of Agriculture.)

VOL. 19, No. 2, OCTOBER 1976 165

the average yield for that year. We tested flat vs ridged planting; clear plastic germination cap vs no germination cap; rototilling vs plowing (1 1-in. deep) vs soil compaction; chloride fertilization; and phosphorus fertilization treatments during the 4 years.

Nitrogen (N) as ammonium nitrate (33-0-0) was broadcast at a rate of 1 00 lb N/acre/year on the experimental area before planting in 1966 through 1968, and at 150 lb N/acre in 1969. Treble superphos-phate (0-46-0) was broadcast at a rate of 100 lb P2O5 acre on the experi-mental area before planting in 1966 and 1969, and at a rate of 50 lb P2O5/acre in 1967 and 1968. All fertilizer was disked into the surface soil.

The replicated plots were planted on May 10, May 17, May 2, and May 9, and 104-ft2 were harvested on Sept. 27, Sept. 26, Oct. 16, and Oct. 1 in 1966 through 1969, respectively. Both fresh and dry matter yields of roots and tops were determined.

Four additional nonreplicated main plots were established on May 17, 1967 for growth-rate measurement over a range of tillage treatments. One 60-ft2 subplot from each main plot was harvested for both fresh and dry matter yields of roots and tops on July 12, 17 and 27, on Aug. 3, 9, 16 and 30, and on Sept. 13 and 26.

Non replicated plots were established again in 1968 for growth-rate determination as functions of calendar date and days since plant-ing. These plots were planted on 4 dates — April 18, and May 2, 16, and 28 — and were dovetailed together so progressive harvests could be taken from adjacent rows and include one row planted on each date. From each date-of-planting plot, 60-ft2 were harvested for both fresh and dry matter yields of roots and tops on July 10, 18 and 26, on Aug. 2, 7, and 22, on Sept. 4 and 16, and on Oct. 2 and 16.

In 1969, the three planting dates were replaced by three chloride fertilizer treatments in plots planted on May 9. Growth rate measure-ments were obtained by harvesting one 40-ft2 subplot from each fertilizer treatment to determine both fresh and dry matter yields of roots and tops on July 23 and 29, on Aug. 13 and 26, on Sept. 9 and 24, and on Oct. 6.

All fresh root yields were adjusted for the sugar factory tare, but root dry matter yields were not.

Theoretical photosynthetic rates (Pr) were calculated according to the method described by deWit (17). The following standard condi-tions were defined by deWit and have been assumed for these theore-tical calculations: (1) maximum Pr for very high light intensity is about 20 kg CH2O ha - 1hr - 1 ; (2) light intensity at which half-of-maximum Pr occurs is about 0.056 langley min-1; (3) canopy density is about 0.1; (4) leaf area index is 5, and (5) CO2 exchange resistance is 0.5 sec cm-1. Approximate values of clear sky radiation in the 400 to


700 mμ wavelength range (HC), photosynthetic rate on clear days (PC), and photosynthetic rate on overcast days (PO) were calculated by linear interpolation from deWit's Table 6. To perform a series of calculations involving different time intervals for different years at one location, calculation time can be reduced by preparing curves to describe HC, PC, and PO as functions of date.

Cloudiness (F) and P were calculated as follows (17):

where PAR is the measured photosynthetically active radiation (400-700 mμ wavelength range) in langleys/day, HC is in langleys/day, and PC, PO, and P r are in kg carbohydrate h a - 1 d a y - 1 . Theoretical photo-synthesis (P) for a time interval is calculated as follows:

Photosynthetic efficiency (PE) is the actual increase in plant dry matter expressed as a percent of P. The plant dry matter actually measured is assumed equivalent to an equal weight of carbohydrate.

Results and Discussion Long term weather records (16) indicate that Carrington has 121

days during which the chance is 50% that the temperature will not drop below 32°F, and 137 days during which the chance is 50% that the temperature will not drop below 28°F. Hence, the growing season is about 130 days. T h e 1968 growing season is an example of the ad-verse weather extremes that can and do occur. T h e last spring frost (T = 22°F) was on May 5, a severe hail storm occurred on July 19, and the temperature dropped to 30°F on August 14 — giving a true frost-free period of only 101 days.

Root growth and total dry matter production are shown as func-tions of calendar date in Figures 1 and 2, respectively, for 1967, 1968, and 1969 at Carrington. Even though these experiments were non-replicated, treatment differences were small each year except 1968. Final dry matter yields for the three earliest planting dates in 1968 were within ± 6 % of the mean, but the yield for the latest planting (May 28) was only 64% of that mean and the data for that latest 1968 planting were excluded. Hence, the data points in Figures 1 and 2 are averages for four plots in 1967 and for three plots in 1968 and 1969.

These data show that (1) about 64, 87, and 72 days after planting were needed to produce the first ton/acre of fresh roots in 1967, 1968

VOL. 19, No. 2, OCTOBER 1976 167

DATE Figure 1. — Average root yield as a function of time for 3 years at Carring-

ton, North Dakota.

DATE Figure 2. — Average dry matter yield as a function of time for 3 years at

Carrington, North Dakota.

168 JOURNAL OF THE A.S.S.B.T,

a n d 1969, respect ively (Fig. 1); a n d (2) a b o u t the s a m e n u m b e r of days (69, 100, a n d 74 days in 1967, 1968, a n d 1969, respect ively) were n e e d e d to p r o d u c e t h e first t on / ac r e o f d ry m a t t e r (Fig. 2). T h e s e in tervals r e p r e s e n t be tween 5 0 % a n d 7 5 % o f t h e avai lable g r o w i n g season a t C a r r i n g t o n . Data p u b l i s h e d by C a m p b e l l a n d Viets (5) indi-ca ted t h a t a b o u t 80 days w e r e n e e d e d to p r o d u c e t h e first t on / ac r e o f roo t s a t H u n t l e y , M o n t a n a . Da ta p u b l i s h e d by Follett , e t al. (7) indi-ca ted tha t a b o u t 80 days w e r e n e e d e d t o p r o d u c e t h e f i r s t t o n / a c r e of d ry m a t t e r a t For t Col l ins , C o l o r a d o .

T h e s e d a t a also show t h a t o n c e t he s u g a r b e e t s b e g a n s to r ing p h o t o s y n t h e t i c p r o d u c t s they g r ew very well a t C a r r i n g t o n . D u r i n g late J u l y a n d all o f A u g u s t o f 1967 a n d 1969, m a x i m u m g r o w t h ra tes (in lb/acre/wk) w e r e a b o u t 6 ,000 , 9 0 0 a n d 2 ,000 for roo t s , suc rose a n d d r y m a t t e r , respect ively . Even with t he a d v e r s e w e a t h e r in 1968, g r o w t h ra tes w e r e m o r e t h a n ha l f t hose for m o r e favorable yea r s (1967 a n d 1969). Yield is a func t ion of bo th g r o w t h ra te a n d t ime , so any prac t ice e x t e n d i n g this active p r o d u c t i o n p e r i o d to ea r l i e r in t h e s u m -m e r w o u l d significantly inc rease final yield.

T h e resul ts o f t he ear ly-season r o o t - g r o w t h s tudy in 1968 a r e s u m m a r i z e d in F i g u r e 3 . F igu re 3A p r e s e n t s t he r o o t - g r o w t h d a t a as

JULY AUGUST SEPTEMBER

D A T E DAYS AFTER PLANTING

Figure 3. — Root yield for various dates of planting, as functions of calen-dar date (A) and days after planting (B) at Carrington, North Dakota.

V O L . 19, N o . 2 , O C T O B E R 1976 169

functions of calendar date and Figure 3B presents them as functions of days after planting. If initiation of bulking were principally a func-tion of ambient weather conditions, the root yield curves would cluster in Figure 3A. If initiation of bulking were principally a function of endogenous characteristics of the sugarbeet plant, the root yield curves would cluster in Figure 3B. Since the curves did not cluster in either A or B, dominance of neither climate nor endogenous factors can be concluded. However, the fact that the root yield curves by days after planting (Figure 3B) are arrayed in reverse order from those by calen-dar date (Fig. 3A) indicates that both climatic and biological factors exert significant influence.

The effect of the hail storm is particularly evident in the root yield curves for April 18, the earliest planting (Fig. 3). The earliest planting produced greater yields than the later plantings at each harvest until mid-September. By final harvest in mid-October, the root yields for the April 18, May 2 and May 16 plantings were about equal. As has been previously noted, the root yield for the May 28 planting was consistently less; so early planting is important when the limited length of the growing season is considered. Carlson et al. (6) reached a similar conclusion about early planting of sugarbeets in the northern Great Plains.

In replicated experiments conducted with a variety of treatments in 1966, 1967 and 1969, treatment differences each year were not sta-tistically significant. Analysis of variance for the randomized block experiment with years as treatments and with sugarbeets grown on the same plots each year (1966 and 1969) showed that years were sig-nificantly different. Since (1) the investigations included several treat-ments, (2) weather is obviously different from year to year, and (3) only years had a significant effect on yields, it follows that yearly weather must be a regulator of sugarbeet growth and yield.

Since treatment differences each year at Carrington were not significant, average annual yields are presented in Table 1. Average yields from Campbell and Viets (5) at Huntley, Montana and Follett, et al. (7) at Fort Collins, Colorado (for the commercial sugarbeet cul-tivar) are also included in Table 1 for comparison, even though those averages include statistically significant treatment differences. The latitudes for the three locations are 47°31' N, 45°45' N, and 40°35' N for Carrington, Huntley, and Fort Collins, respectively. Therefore, Carrington is about 125 miles north of Huntley and about 500 miles north of Fort Collins. Carrington, Huntley and Fort Collins are 1,580, 3,100 and 5,000 ft above mean sea level, respectively. Sugarbeets were planted on April 2, 1961 at Huntley and on April 4, 1962 at Fort Collins — 37, 44, 29 and 36 days earlier than the planting dates at Carrington in 1966, 1967, 1968 and 1969, respectively.

For all measured components of yield, production was highest


Table 1. — Average yields and calculated theoretical photosynthesis for Carring-ton, Huntley 2, and Fort Collins. 3

Number of plots Average dry matter (tons/acre) Average root vield (tons/acre) Average sucrose (cwt/acre)

Theoretical P (tons DM/acre)4

Weighted-average cloudiness (%)

1966

18 6.3

14.9 50.9 10.4 42

Carri 1967

22 7.0

19.4 62.7 11.7 2 3

ngton 1968 1

3 6.3

14.2 42.5 11.0 29

1969

3 3

6.9

17.8 51.8 12.1 2 4

Huntley 2

1961 4 0

7.9

21.6 58.8 17.25

3 6 5

Fort Col l ins 3

1962

12

8.9

24.1 81.0 18.7s

3 0 5

1Hail in July, frost in August 2From Campbell & Viets (1967) 3From Follett, et al. (1970) 4By deVVitt method for period from first ton of roots per acre to harvest 5June 22 was selected as date for first ton of roots per acre

at Carrington in 1967. Yield differences between years and locations are obvious (Table 1). If adjustments can be made for differences in ambient weather conditions, the remaining differences would be due to treatment differences, i.e. soil, fertility, variety, etc.

One method of adjusting for weather is to express each growing season in terms of a standard environment like that described by deWit (17). Using the deWit model requires that photosynthetically active radiation (wavelength range of 400 to 700 mμ be measured during the growing season. Photosynthetically active radiation (PAR) data were not available for Carrington, but PAR is about half of the total solar radiation (2, 8, 17). Tota l solar radiat ion data were available for Bismarck, North Dakota (15), which is about 40 miles south and 100 miles west of Carrington.

To justify using a 2:1 ratio to relate total solar radiation and PAR, five years (1965 to 1969) of daily total solar radiation data were com-pared to twice deWit's light intensity values. The results are shown in Figure 4, and the curve constructed by doubling deWit's HC values satisfactorily envelopes that measured total radiation from mid-May through October. T h e fact that the deWit envelope is low for March and April is of little or no consequence because sugarbeet plants are usually too small to justify photosynthesis calculations before about mid-June in the northern Great Plains.

Theoretical photosynthetic rates (P r) are easily calculated as des-cribed by deWit (17) after the appropriate curves for photosynthetic rates on clear and overcast days have been constructed. Table 1 shows theoretical photosynthesis for the part of the growing season between the production of the first ton/acre of roots and harvest during six dif-ferent years and at three locations. With P values thus predicted by the deWit model ranging from 10.4 to 18.7 tons/acre, the growing season weather conditions were indeed different. Using only that part of the growing season after the first ton/acre of roots were produced

VOL. 19, No. 2, OCTOBER 1976 171

Figure 4. — Comparison of measured solar radiation for 1965-1969 at Bismarck, North Dakota (15) and 2 times deWit's HC (17).

is justified on the basis of the growth data presented in Figs. 1 and 2. The first ton/acre of roots is produced about the time when the leaf area index equalled or exceeded 2. Hence, the plant canopy could intercept and utilize the available radiation.

Maximum radiation is expected during the latter part of June in the northern Great Plains. The first ton/acre of roots was produced by about June 22 for both the Huntley (5) and Fort Collins (7) experi-ments. Hence, the accumulation of root dry matter and sucrose occurred during the period when radiation decreased with time. At Carrington, the situation was even less desirable because the first ton/acre of roots was not produced until the latter part of July, about 4 or 5 weeks after the peak of the radiation cycle. Thus, a significant amount of available radiation was not used for photosynthesis, parti-cularly at Carrington, because the plants were too small.

Cloudiness and atmospheric contamination which reduces the effective radiation level at the land surface is related to daily weather. Daily weather varies considerably from place to place at any one time. At any one place, daily weather varies considerably with time as a result of weather systems that generally -move from west to east across the northern Great Plains. Because of these moving weather systems, average cloudiness for different locations in the northern Great Plains during any one growing season will be about equal; and weighted-average level of cloudiness from year to year becomes a function of the intensity and frequency of occurrence of those weather systems from year to year. Calculation of relative cloudiness is involved in the calculation of theoretical photosynthesis. Even though the weighted-average levels of cloudiness ranged from 23% to 42% (Table 1) and were calculated for the same time interval as the corresponding P,


weighted-average levels of cloudiness should be viewed only as quali-tative indicators of a growing season condition.

Table 2 presents photosynthetic efficiencies (PE) calculated for the root storage part of the growth cycle at Carrington plus the re-ported PE for Huntley (5) and Fort Collins (7). Although average yields at Carrington were lower than those at the other two locations, PE were highest at Carrington. Theoretical P values (Table 1) were considerably larger at both Huntley and Fort Collins than at Carring-ton. Therefore, yields at Huntley and Fort Collins must have been higher because of the longer growing season that resulted because earlier planting was possible and plants developed in time to intercept and utilize more of the available radiation.

By expressing each yield component as a fraction of the corres-ponding yield component for one set of conditions, or one year, the results for various years or locations are referenced to a common base. This has been done in the top half of Table 3, arbitrarily using 1967 yield components as common denominators. Each yield component for 1967 is thus reduced to unity, and all other yield components be-come ratios relative to 1967 production components.

Table 2. — Photosynthetic efficiencies for the root storage portion of the growth cycle at Carrington, Huntley,1 and Fort Collins.2

1From Campbell & Viets (1967) 2From Follett, et al. (1970)

Table 3. — Yield ratios for 4 years at Carrington and 1 year each at Huntley1 and Fort Collins,2 using 1967 yield components and calculated theoretical photosyn-thesis as bases.

Theoretical P Dry matter Fresh roots Sucrose Theoretical P Dry matter Fresh roots Sucrose

1966 0.89 0.90 0.77 0.81 1.00 1.01 0.87 0.91

Carrington

1967 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

1968* 0.94 0.90 0.73 0.68 1.00 0.96 0.78 0.72

1969 1.03 0.99 0.92 0.83 1.00 0.96 0.89 0.81

Huntley1

1961 1.47 1.13 1.11 0.94 1.00 0.77 0.76 0.64

Fort Collins2

1962 1.60 1.27 1.24 1.29 1.00 0.79 0.78 0.81

*Hail in July, frost in August 1Derived from Campbell & Viets (1967) 2Derived from Follett, et al. (1970)

July 19 to Sept. 26, 1967 Aug. 2 to Oct. 16, 1968 July 23 to Oct. 6, 1969 July 10 to Oct. 5, 1961' June 9 to Oct. 1 1, 19622

Days 69 75 75 87

124

P E

% 56 41 57 39 39

VOL. 19, No. 2, OCTOBER 1976 173

*Hail in July, frost in August 'Derived from Campbell & Viets (1967) 2Derived from Follett, et al. (1970)

By further dividing each component by that year's theoretical P ratio, the theoretical difference in climate as described by the deWit model is removed, and the resultant yield component ratios are all referenced to standard conditions represented by 1967 production components and 1 967 weather conditions at Carrington. These results are presented in the lower half of Table 3. Since this normalizing pro-cedure did not reduce all yield component ratios to unity, we can conclude that the remaining yield difference between years and be-tween locations were caused by something other than climatic factors evaluated by the deWit model, i.e. soil conditions, variety differences, disease, fertility, management differences, or other treatment con-ditions.

Equivalent comparisons can be developed with each yield com-ponent expressed in usual yield units instead of ratios by dividing first the theoretical P values for each year by the theoretical P value for the chosen year. Each year's measured yield component is then divided by that year's theoretical P ratio to give the expected yield for the standardized condition. The procedure is illustrated in Table 4, with the yields normalized to 1967 weather conditions at Carrington.

Summary Sugarbeet growth in the northern Great Plains varies considerably

from year to year. During four study years at Carrington, North Dakota, irrigated plot yields averaged 16.6 tons/acre of roots while field yields averaged 13.6 tons/acre. Sucrose yields averaged 52.0 cwt/acre for the plots and 47.8 cwt/acre for the field.

Growth studies during favorable growing seasons revealed that from 64 to 72 days (over half the growing season) were required to produce the first ton/acre of roots. Similarity, from 69 to 74 days were required to produce the first ton/acre of dry matter. Consequently, the root storage portion of the growth cycle occurs after the maximum in the annual radiation cycle.

Theoretical P ratio Normalized yields

Dry matter (tons/acre) Fresh roots (tons/acre) Sucrose (c.wt/acre)

1966 0.89

7.1 16.7 57.2

Carrington 1967

1.00

7.0 19.4 62.7

1968* 0.94

6.7 15.1 45.2

1969 1.03

6.7 17.3 50.3

Huntley1

1961 1.47

5.4 14.7 40.0

Fort Collins2

1962 1.60

5.6 15.1 50.6

Table 4. — Theoretical photosynthesis ratios and yield components for six dif-ferent years normalized to 1967 weather conditions at Carrington, North Dakota.


B o t h w e a t h e r a n d e n d o g e n o u s factors i n f luenced the ini t iat ion o f r oo t bu lk ing . O n c e t h e f i r s t t o n / a c r e o f roo t s w e r e p r o d u c e d , weekly g r o w t h ra tes w e r e as h igh as 6 ,000 , 900 a n d 2 ,000 lb/acre for roo ts , suc rose a n d d r y m a t t e r , r espec t ive ly . H e n c e , g e n e t i c o r c u l t u r a l c h a n g e s which h a s t e n t h e ini t ia t ion o f b u l k i n g w o u l d significantly increase s u g a r b e e t yields.

Ca l cu l a t i on o f t h e o r e t i c a l p h o t o s y n t h e s i s by d e W i t ' s m e t h o d revea led t h a t w e a t h e r cond i t i ons d u r i n g six d i f f e ren t years a t t h r e e locat ions w e r e i n d e e d d i f f e r en t . T h e o r e t i c a l P va lues for t h e six g r o w i n g seasons r a n g e d f rom 10.4 to 18.7 tons /ac re o f d r y m a t t e r . For these ca lcula t ions , on ly t h e r o o t s t o r age pa r t o f t h e g r o w t h cycle was u sed , i.e. t h e t ime in te rva l s t a r t i ng with p r o d u c t i o n of 1 t on / ac re of roo ts a n d a leaf a r e a i n d e x of a b o u t 2 a n d e n d i n g with ha rves t .

Pho tosyn the t i c efficiencies based o n m e a s u r e d d r y m a t t e r p r o -duc t ion a n d t h e de Wit m o d e l for ca lcu la t ing theore t i ca l p h o t o s y n t h e s i s r a n g e d f rom 4 1 % t o 5 7 % d u r i n g t h e roo t s to rage par t o f t h e g r o w t h cycle a t C a r r i n g t o n .

A m e t h o d is de sc r i bed by which deWi t ' s t heo re t i ca l p h o t o s y n -thesis can be u s e d to c o m p e n s a t e for c l imatic d i f fe rences be tween years a n d locat ions. T h e deWi t m o d e l a ccoun t s p r imar i l y for r ad i a -tion d i f f e rences in c o m b i n a t i o n with c loud iness a n d r e l a t ed a t m o s -p h e r i c c o n t a m i n a t i o n . C o n t i n u o u s losses o f d r y m a t t e r by r e sp i r a t i on , a d v e c t e d e n e r g y , w ind , air t e m p e r a t u r e , e tc . a r e n o t c o n s i d e r e d . In spite of these l imi ta t ions , h o w e v e r , t he m e t h o d i s easy to use a n d p rov ide s a m e a n s of eva lua t ing g r o w i n g season cl imatic c o n d i t i o n s so t ha t g r o w t h a t d i f f e ren t locat ions a n d d u r i n g d i f fe ren t years can b e c o m p a r e d .

A c k n o w l e d g e m e n t

Sincere t h a n k s a r e e x t e n d e d to J . P . H a r m s a n d W. A. Sel lner , A g r i c u l t u r a l R e s e a r c h T e c h n i c i a n s , for t h e i r f i e ld a n d laboratory-assis tance, a n d to Holly S u g a r C o r p o r a t i o n , S idney , M o n t a n a for p r o v i d i n g seed a n d factory t a r e a n d sucrose analyses .

Literature Cited (1) AFANASIEVE, M. M. 1964. T h e effect of simulated hail injuries on yield

and sugar content of beets. J. Am. Soc. Sugar Beet Technol. 13: 225-237.

(2) ALLEN, L. H., Jr . , D. W. STEWART, and E. R. LEMON. 1974. Photosynthe-sis in plant canopies: Effect of light response curves and radiation source geometry. Photosvnthetica 8(3): 184-207.

(3) BENZ, L. C , W. O . WILLIS, H . J . HAAS, and E.J . DOERING 1971. Effects of plastic covers and between-row soil ridges on sugarbeets and soil salinity. Proc. of Tenth National Agric. Plastics Conf., J. W. Courter, Editor. Chicago, 111. pp. 48-62.

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(4) BOND, J . J . , J. F. POWER, and H. M. OLSON. 1970. Rotating-boom plot irrigator with offset mounting. Trans . Am. Soc. of Agric. Eng. 13: 143-144, 147.

(5) CAMPBELL, R. E. and F. G. VIETS, Jr . 1967. Yield and sugar production by sugar beets as affected by leaf area variations induced by stand density and nitrogen fertilization. Agron. J. 59: 349-354.

(6) CARLSON, C. W., D. L. GRLNES, L. O. FINE, G. A. REICHMAN, H. R. HAISE, J. ALESSI, and R. E. CAMPBELL. 1961. Soil, water and crop manage-ment on newly irrigated lands in the Dakotas. U.S. Dept. of Agric. Prod. Res. Rpt. No. 53.

(7) FOLLETT, R. F., W. R. SCHMEHL, and F. G. VIETS, J r . 1970. Seasonal leaf area, dry weight, and sucrose accumulation by sugarbeets. J. Am. Soc. Sugar Beet Technol. 16(3): 235-252.

(8) GAASTRA, P. 1963. Climatic control of photosynthesis and respiration. In L. T. Evans (ed.) Environmental control of plant growth. Academic Press, New York and London, pp. 113-140.

(9) RADKE, J. F. and R. E. BAUER. 1969. Growth of Sugarbeets as affected by root temperatures: Part I. Greenhouse studies. Agron. J. 61 : 860-863.

(10) SHAW, Robert H. and Wesley F. BUCHELE. 195 7. The effect of the shape of the soil surface profile on soil temperature and moisture. Iowa State College J. of Sci. 32(1): 95-104.

(11) SWIFT, Edward L. and Frank A. CLELLAND. 1946. The effect of climate on sugarbeet yields in western Montana. Am. Soc. of Sugar Beet Technol., Proc. 4th General Meeting: 135-140.

(12) ULRICH, Albert. 1952. Influence of temperature and light factors on the growth and development of sugarbeets in controlled climate envi-ronment. Agron. J. 44: 66-73.

(13) ULRICH, Albert. 1955. Influence of night temperature and nitrogen nutrition on growth, sucrose accumulation, and leaf minerals of sugarbeet plants. Plant Physiol. 30: 250-257.

(14) ULRICH, Albert, Kenneth OHKI , David RIRIE, F.J. H, et al. 1958. Effects of climate on sugarbeets grown under standardized conditions. J. Am. Soc. Sugar Beet Technol. 10(1): 1-23.

(15) U. S. Dept. of Commerce, National Oceanic and Atmospheric Admin-istration. Climatological Data, National Summary.

(16) U. S. Department of Commerce, National Oceanic and Atmospheric Administration. Climatological Data. North Dakota, Annual Summary.

(17) W I T , C. T. de. 1965. Photosynthesis of leaf canopies. Institute for Biolo-gical and Chemical Research on Field Crops and Herbage. Wagen-ingen, Netherlands. Agricultural Research Report No. 663. 57 pp.

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