soil sampling for scn seed treatments for scn decline of...

2/23/17

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Greg Tylka & Kaitlyn BissonnetteISU Department of

Plant Pathology and Microbiology

Seed Treatments for SCN

Soil Sampling for SCN&

&Decline of SCN Resistance in Iowa

● ~24 days per generation

● 3-6 generations per year

● >200 eggs per female

swollenjuvenile

Tylka

Tylka

female+eggscyst (dead female)full of eggs

Tylka

Tylka

juveniles

Tylka

adultfemale

adult male

Baum

adult female and male –mating occurson root

Tylka

eggs

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Soil Sampling for SCN

l How to sample?

ü 15 to 20 one-inch-diameter soil cores, 6 to 8 inches deep

ü soil cores collected in a zig zag or “M” pattern

ü one 15- to 20-core sample for every 20 acres

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Use a zigzagpattern when collecting soilcores.

OR

Collect soilcores fromlogical areasor “management zones” in field.

OR

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Collect soilcores fromhigh-risk areas in the field.

l How to sample?l When to sample?

ü spring sampling before soybean cropü fall sampling of soybean stubbleü fall sampling of nonhost crop

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l How to sample?l When to sample?

ü spring sampling before soybean cropü fall sampling of soybean stubbleü fall sampling of nonhost cropü during the season

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l How to sample?l When to sample?l Variability of results

Why are SCN soil sample results so variable?

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80 ft

40ft

Curtiss Farm 2000 – Pre Experiment Sampling

Four 10-core soil samples collected in March 2000, one from each quadrant of the experimental site (1/20 acre each)

X X X

X X X

X X

X X

X X X

X X X

X X

X X

X X X

X X X

X X

X X

X X X

X X X

X X

X X

80 ft

40ft

Curtiss Farm 2000 – Pre Experiment Sampling

Four 10-core soil samples collected in March 2000, one from each quadrant of the experimental site (1/20 acre each)

0

00

0

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Curtiss Farm 2000 – Initial Population Densities(eggs per 100 cc soil)

0 0 0 0 0 0 0 50

0 0 0 0 0 0 0 0

0 100 0 0 0 0 0 0

0 50 0 0 0 0 0 50

0 0 0 0 0 0 50 0500 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

10-core soil sample collected from center 12 ft of center 2 rows of each 4-row x 20-ft plot (64 total, 1/200 acre each) at planting20 ft

10ft

Curtiss Farm 2000 – Final Population Densities(eggs per 100 cc soil)

10-core soil sample collected from center 12 ft of center2 rows of each 4-row x 20-ft plot (64 total, 1/200 acre each) at harvest20 ft

10ft

11,000 5,100 2,900 3,200 350 250 750 2,200

4,100 1,900 1,900 5,900 1,000 2,600 0 100

32,600 19,500 23,700 11,600 8,200 6,400 10,900 3,400

37,000 7,600 9,400 8,400 6,400 6,200 10,700 1,700

16,500 17,600 6,000 1,500 0 3,700 3,700 6,100

19,700 7,600 2,300 50 450 700 250 1,600

12,600 10,600 100 50 0 0 0 50

9,000 4,800 850 0 250 0 0 500

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Why are SCN soil sample results so variable?

egg count = 1,500

egg count = 0

§ List of all avail seed treatments and MOABrand name Crop(s)Targeted

nematodesActive

ingredientMode

of actioncotton, corn, soybean all ppn abamectin

inhibits nerve transmission

all all ppn harpin protein bolsters natural plant defenses

cotton, corn, soybean all ppn Bacillus firmus

repels nematodes from roots

soybean SCN Pasteuria nishizawae nematode parasite

soybean SCN, RKN fluopyram SDHI enzyme inhibitor

cotton, corn, soybean

SCN, RKN,reniform, lesion

tioxazafen mitochondrial translation inhibitor

corn, soybean SCN, reniform, lesionBacillus amylo-‐liquefaciens under investigation

Seed Treatments for SCN

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Clariva§ 9 locations, 3 years

§ 27 site years

§ 12 replicates§ Treatments

§ Cruiser Maxx Advanced + Vibrance [CM+V]

§ Clariva Complete Beans (Cruiser Maxx Advanced + Vibrance + Pasteuria nishizawae) [Clariva]

§ Variety§ 2014 -‐ Asgrow 2433 (MR)§ 2015-‐2016 – NK Soybeans 22-‐S1 (R)

Ilevo§ 9 locations, 2 years

§ 18 site years

§ 12 replicates§ Treatments

§ Poncho/Votivo [PV]§ Poncho/Votivo + Ilevo(fluopyram) [Ilevo]

§ Variety § Asgrow 2031 (R)

Both § Reproductive Factor (RF)§ Yield (Bu/Acre)

Materials and Methods

Materials and Methods

SC

WC

NC NE

C EC

NW

SW SE

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Clariva Experiments

Results: Clariva – 2014

“Clariva” RF

“CM+V” RF

“Clariva” RF minus

“CM+V” RFP -‐ value

Northern 2.96 3.35 -‐0.39 0.77

Central1.34 1.91 -‐0.57 0.17

Southern2.48 3.00 -‐0.52 0.56

Combined2.26 2.75 -‐0.49 0.09

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

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“Clariva” Yield

“CM+V” Yield

“Clariva” Yield minus “CM+V”

YieldP -‐ value

Northern 53.7 52.5 1.2 0.58

Central67.2 67.8 -‐0.6 0.76

Southern58.9 58.7 0.2 0.95

Combined59.9 59.7 0.2 0.64

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE


“Clariva” RF

“CM+V” RF



Northern 1.75 2.22 -‐0.47 0.69

Central1.14 1.44 -‐0.30 0.24

Southern1.66 2.09 -‐0.43 0.54

Combined1.52 1.92 -‐0.40 0.34

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

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“Clariva” Yield

“CM+V” Yield


YieldP -‐ value

Northern 70.7 71.4 -‐0.7 0.76

Central69.0 69.3 -‐0.3 0.85

Southern61.7 62.8 -‐1.1 0.56

Combined67.1 67.8 -‐0.7 0.04

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE


“Clariva” RF

“CM+V” RF



Northern 9.80 11.44 -‐1.64 0.73

Central5.60 6.73 -‐1.13 0.57

Southern1.23 0.80 0.43 0.20

Combined5.55 6.33 -‐0.78 0.45

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

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“Clariva” Yield

“CM+V” Yield


YieldP -‐ value

Northern 69.1 67.1 2.0 0.55

Central74.0 74.8 -‐0.8 0.61

Southern64.2 63.3 0.9 0.82

Combined69.1 68.4 0.7 0.28

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

Results: Clariva – 2014 – 2016

“Clariva” RF

“CM+V” RF



Northern 4.84 5.67 -‐0.83 0.63

Central2.70 3.36 -‐0.66 0.32

Southern1.79 1.97 -‐0.18 0.65

Combined3.11 3.67 -‐0.56 0.37

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

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Results: Clariva – 2014 – 2016

“Clariva” Yield

“CM+V” Yield


YieldP -‐ value

Northern 64.5 63.7 0.8 0.62

Central70.1 70.6 -‐0.5 0.58

Southern61.6 61.6 0.0 0.99

Combined65.4 65.3 0.1 0.92

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

Discussion -‐ Clariva§Reproductive factor§Variability – individual locations§Only significant over all locations in 2014

§Yield§No yield effects in 2014 or 2016 § Even at individual locations§ Significant only in SC location over all 3 years

§No significant yield increases across environments

§Variable over years and locations§Site specific

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Ilevo Experiments

Results: Ilevo – 2015

“Ilevo” RF “PV” RF“Ilevo” RF minus “PV”

RFP -‐ value

Northern 1.26 1.16 0.10 0.66

Central1.44 2.09 -‐0.65 0.20

Southern2.30 1.92 0.38 0.56

Combined1.67 1.72 -‐0.05 0.82

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

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“Ilevo” Yield “PV” Yield“Ilevo” Yield minus “PV”

YieldP -‐ value

Northern 68.8 68.7 0.1 0.98

Central70.7 70.1 0.6 0.80

Southern58.4 58.7 -‐0.3 0.91

Combined65.9 65.8 0.1 0.77

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE



RFP -‐ value

Northern 6.11 9.09 -‐2.98 0.33

Central7.51 5.84 1.67 0.29

Southern0.99 1.27 -‐0.28 0.32

Combined4.87 5.40 -‐0.53 0.53

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

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YieldP -‐ value

Northern 80.6 78.1 2.5 0.03

Central75.0 75.1 -‐0.1 0.92

Southern64.9 65.8 -‐0.9 0.81

Combined73.5 73.0 0.5 0.34

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

Results: Ilevo – 2015 – 2016


RFP -‐ value

Northern 3.69 5.12 -‐1.43 0.17

Central4.48 3.98 0.50 0.49

Southern1.64 1.59 0.05 0.86

Combined3.27 3.56 -‐0.29 0.50

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

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Results: Ilevo – 2015 – 2016


YieldP -‐ value

Northern 74.7 73.4 1.3 0.03

Central72.9 72.6 0.3 0.67

Southern61.6 62.2 -‐0.6 0.26

Combined69.7 69.4 0.3 0.35

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

SC

WC

NC NE

C EC

NW

SW SE

Discussion -‐ Ilevo§Reproductive factor§Variability – individual locations

§Yield§Significant yield increase in 2016 and over all years (Northern District)

§No significant yield increases across other environments

§Variable over years and locations§Site specific§Northern sites in 2016 may have impacted overall effects

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§ List of all avail seed treatments and MOABrand name Crop(s)Targeted

nematodesActive

ingredientMode

of actioncotton, corn, soybean all ppn abamectin

inhibits nerve transmission

all all ppn harpin protein bolsters natural plant defenses

cotton, corn, soybean all ppn Bacillus firmus

repels nematodes from roots

soybean SCN Pasteuria nishizawae nematode parasite

soybean SCN, RKN fluopyram SDHI enzyme inhibitor

cotton, corn, soybean

SCN, RKN,reniform, lesion

tioxazafen mitochondrial translation inhibitor

corn, soybean SCN, reniform, lesionBacillus amylo-‐liquefaciens under investigation

susceptiblesoybean variety

resistantsoybean variety

Decline of SCN Resistance in Iowa

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bushels per acre

52.7

45.9

Yield and SCN ControlSCN-resistant vs Susceptible Soybean Varieties

East Central Iowa(1,310 eggs/100 cm3 at planting)

0

2,000

4,000

6,000

8,000

10,000 eggs per 100 cm3soil at harvest

bushels per acre

52.7

45.9

2,169

8,875

SCN

Yield and SCN ControlSCN-resistant vs Susceptible Soybean Varieties

East Central Iowa(1,310 eggs/100 cm3 at planting)

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● SCN resistance requires several genes (Rhg genes) in the soybean plant

● no legal definition for SCN resistance in US

● no government verification of SCN resistance in US

● scientific definition of resistance

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01002003004005006007008009001000

Number of SCN-resistant Soybean Varieties Available for Iowa (MG 0-3)

1991 - 2016Num

ber of varieties

956

29

Registered Germplasm Lines that areSources of SCN Resistance for Breeding

• PI 548402 (Peking)• PI 88788• PI 90763• PI 437654

There are many other soybean breeding lines with different sources of resistance to SCN identified and released by breeders as well.

• PI 209332• PI 89772• PI 548318 (Cloud)

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01002003004005006007008009001000

01002003004005006007008009001000

PI 88788Other

Num

ber of varieties

Number of SCN-resistant Soybean Varieties Available for Iowa (MG 0-3)

1991 - 2016

927*

29**

956

* 927 of 956 varieties have PI 88788 source of SCN resistance

29

** 26 of 29 non-PI 88788 varieties have Peking source of SCN resistance

*** almost all new soybean varieties have PI 88788 SCN resistance

What would happen if a single herbicidewas used over and over again for 20 years???

Glyphosate-susceptible (left) and glyphosate-resistant (right) common ragweed populations three weeks after application of 44 oz/acre of Roundup PowerMax.Source: University Nebraska-Lincoln CropWatch

~3 percent survival 100 percent survival

same thing happening with

PI 88788 SCN resistance

percent SCN reproduction on SCN-resistant variety

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Iowa State University SCN-resistant Soybean Variety Trial Program

From 1991 to 1999, almost all SCN populations in variety trial fields had

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y = -0.3798x + 59.726R² = 0.14294

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40

SCN Reproductive Factor (Pf/Pi)

Yiel

d (b

u/ac

re)

each data point represents the MEAN yield of all resistant varieties with PI 88788 in the variety trial field experiments

Build-up of SCN Numbers on PI 88788 versus Yield

McCarville et al., 2017

We are now losing soybean yield to SCN with resistant varieties and that will increase in the future.

Prospects for the Future

• usefulness of traditional PI 88788 SCN resistance will continue to decline – but keep using resistant varieties

PI 88788 resistantsoybean variety PI 88788 resistant

soybean variety

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Prospects for the Future

• usefulness of traditional PI 88788 SCN resistance will continue to decline – but keep using resistant varieties

• new commercial varieties with non-PI 88788 resistance not very likely

susceptiblesoybean variety

PI 88788 resistantsoybean variety

$0.00Photo: University of Minnesota

Thank you!

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