Cutting labor and input costs while increasing fruit size, yield and quality, what’s possible and

what’s not?

Ted DeJong

National farm wages have increased by ~100% over 20 years.

This may be even higher in California and does not include increased costs related to labor management and reporting.

In the same ten year period average US farm fuels expenditures increased by ~59%.

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Acr

es

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30000

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Freestone Peach Acreage

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Acr

es

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Cling Peach Acreage

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Yie

ld p

er

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e (

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s/a

cre

)

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Average Freestone Peach Yields Per Acre

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Average Cling Peach Yields

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/ton)

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Average Gross Value Per Ton

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)

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Time

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Freestone Peaches

Gross Freestone Peach Returns Per Acre

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Cling Peaches

Gross Cling Peach Returns Per Acre

Lopez, Johnson and DeJong, California Agriculture, 2007

It is interesting there has been a consistent marketing trend toward packing larger and larger sized fruit over the past 20 years.

This has been done by preferentially packing larger sized fruit and discarding more fruit in the small size categories.

0 50 100 150 200 250 300 350 400

75

100

125

150

175

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250250

Crop load (no. fruits tree-1)

Fru

it ave

rage fre

sh m

ass

(g fru

it -1)

5

10

15

20

25

30

35

4040

Tota

l Cro

p fre

sh y

ield

(K

g tre

e -1

)

Fruit average fresh massTotal Crop fresh yield

Simulation of commercial practicesOther things being equal, fruit size is inversely related to yield and the relationship is not linear.

1 2 3 4 5 6 7 8 9 10

0.1

0.2

0.3

0.40.5

1 2 3 4 5 6 7 8 9 10

0.1

0.2

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0.40.5

1 2 3 4 5 6 7 8 9 10

0.1

0.2

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1 2 3 4 5 6 7 8 9 10

0.1

0.20.3

0.40.5

1 2 3 4 5 6 7 8 9 100

0.1

0.2

0.3

0.4

0.5

Fruit fresh mass classes

Fractio

n of fr

uit in

class

n = 350

n = 250

n = 200

n = 100

n = 40

To make matters worse the previous figure only showed the relationship between average fruit size and yield. Fruit sizes on a tree are normally distributed so there are always some fruit on the tree that will not make size and at higher crop loads a greater proportion of the crop will not make acceptable size.

But other things are not always equal. In years with warm springs fruit development rates are more rapid and this means fruit growth rates per day must be greater to make up the same amount of size in a shorter amount of time. This is not possible especially if the fruit are not thinned in time.

Thus, fruit size at pit hardening will be smaller and this will very likely carry forward to harvest.

The next few slides will demonstrate how this happens.

It all follows from the Relative Fruit Growth Model that we have developed for peaches.

0

10

20

30

40

50

0 450 900 1350 1800 2250

Degree-days after bloom

Fru

it R

GR

(m

g g-1

dd-1

frui

t-1)

Spring Lady

Cal Red

From Grossman and DeJong 1995

0

10

20

30

40

50

60

70

80

60 80 100 120 140 160 180 200 220

1990

2004

2006

FullBloom

Spring Lady

60 80 100 120 140 160 180 200 220 240

FullBloom

Cal Red

Day of year

Fru

it dr

y w

eigh

t (g

fru

it -1

)

If we use the RGR functions shown on the previous slide to project potential fruit dry weight growth for three contrasting seasons we see substantial differences in the timing of potential fruit sink demands for carbon.

Cal Red

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

60 70 80 90 100 110 120 130 140

1990

2004

2006

Full bloom

Spring Lady

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Full bloom

Day of year

Fru

it ab

solu

te g

row

th r

ate

(g d

ay-1

fru

it-1)

The differences between seasons is even more apparent when potential absolute fruit growth rates of individual fruits are calculated for the first 50 days after bloom.

Cal Red

(2000 fruits tree-1)

0

1000

2000

3000

4000

5000

6000

7000

60 70 80 90 100 110 120 130 140

Full bloom

Spring Lady

(1000 fruits tree-1)

0

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7000

8000199020042006

Full bloom

Day of year

Cum

ulat

ive

dry

wei

ght

grow

th r

equi

rem

ent

(g

tree

-1)

When the individual fruit growth demands are compounded by pre-thinning crop loads during the first 50 days after bloom, the differences in potential carbon demand by the fruit among years are really apparent.

On the other hand, how are the differences in temperature among years like to influence carbon supply to fuel this demand?

• small + effect on leaf Pn rate

• min. effect on canopy Pn because of lack of canopy development within 30 dab

• min. effect on starch mobilization from storage

• greater competition for CH2O from vegetative sinks

Taking the art out of pruning and thinning

Ted DeJong

We have enough understanding to simulate the growth of trees and fruit.

What can you do to maintain or optimize yield, fruit size, and fruit quality

while minimizing costs

• Optimize fertilizer and water management • Select a good training system and renewal prune

to manage fruiting wood and minimize water shoots

• Select high quality cultivars • Reduce crop load and thin early (mechanically (?)

combined with hand thinning)• Lower tree heights (size-controlling rootstocks

and pruning systems)• Explore new methods of mechanical harvest

We have shown experimentally that early thinning can increase fruit size and yield.

Mea

n fr

uit

dry

mas

s (g

fru

it -1)

60 80 100 120 140 160 180 200 220 240 260

10

15

20

25

30

Day of year

UnthinnedThinned 90 days after bloomThinned 60 days after bloomThinned 30 days after blooomThinned at bloom

5

We obtain similar results when we use a crop canopy simulation model.

Table 1. Fruit yield data from four clingstone peach cultivars in commercial orchards near Kingsburg California that were thinned on two different dates in 1992. Data indicate means +- se for six, four-tree replications per cultivar and thinning date. Adapted from DeJong et al. 1992.

Cultivar/Thinning Date

Fruit size(gFW/fruit)

Crop Load(fruit/tree)

Yield(tons/Ha)

Loadel20 March18 May

113.3 ± 1.4 91.9 ± 2.4

1681 ± 641649 ± 40

56.7 ± 2.045.3 ± 1.6

Carson20 March18 May

127.8 ± 4.7108.2 ± 2.5

1576 ± 741427 ± 53

59.4 ± 2.0 46.0 ± 2.0

Andross21 March18 May

123.6 ± 2.1115.0 ± 1.7

1888 ± 961766 ± 58

69.3 ± 2.7 60.8 ± 2.7

Ross27 March19 May

163.9 ± 7.0163.9 ± 3.2

1862 ± 991638 ± 69

80.7 ± 2.5 72.2 ± 3.1

New approaches to mechanical thinning.

The machine on the left is used to reduce flowers at bloom.

The machine below is used in New York and is like what is being tested in California now for olive harvesting.

Rootstock

Loadel Flavorcrest

Open Vase KAC-V Open Vase KAC-V

Nemaguard 78.1±0.68 54.6±0.96 90.2±1.97 62.6±1.17

Controller 9 72.2±2.11 52.6±2.21 86.3±2.59 63.4±3.75

Controller 5 53.0±0.36 38.1±1.69 61.7±1.18 41.6±0.39

After 12 growing seasons trees on Controller 9 had trunk circumferences (cm) that were nearly the same as trees on Nemaguard but trees on Hiawatha and Controller 5 were substantially smaller. Trunk circumferences of the KAC-V trees were also smaller than open vase trees.

Controlling tree size with rootstocks

Tree Age (years)

0 1 2 3 4 5 6 7 8

Dry

Mas

s of

Pru

ning

s (K

g/tr

ee)

0

5

10

15

20

0

5

10

15

20Nemaguard Controller 9Hiawatha Controller 5

Flavorcrest (vase)

Loadel (vase)

Tree Age (years)

0 1 2 3 4 5 6 7 80

2

4

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8

10

12

Dry

Mas

s of

Pru

ning

s (K

g/tr

ee)

0

2

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6

8

10

12 Nemaguard Controller 9Hiawatha Controller 5

Loadel (KAC-V)

Flavorcrest (KAC-V)

Differences in vegetative vigor (as reflected by pruning weights) among trees on different rootstocks were apparent very early in the trial and remained fairly consistent. The differences in vigor are essentially the selling points of the size-controlling rootstocks.

Rootstock

KAC-V

LOADEL FLAVORCREST

Topping Treatment

Crop wght/tr

(kg)

Mean fruit weight (gm)

Mean crop load

(#fruit/tr)

Fruit wght/TCA(kg/cm2)

Crop wght/tr

(kg)

Mean fruit weight(gm)

Mean crop load

(#fruit/tr)

Fruit wght/TCA(kg/cm2)

NemaguardTopped 3.3m 59.8 156.0 384 0.25 43.5 138.8 314 0.14

Topped 2.4m 58.1 142.2 409 0.24 47.5 132.2 359 0.15

Controller 9Topped 3.3m 55.2 146.0 378 0.25 45.9 124.6 369 0.14

Topped 2.4m 57.9 132.0 437 0.26 40.6 128.4 317 0.13

Controller 5Topped 3.3m 41.6 136.2 305 0.36 42.5 117.8 360 0.31

Topped 2.4m 47.7 110.6 432 0.41 39.5 111.7 354 0.28

OPEN VASE

NemaguardTopped 3.3m 117.9 148.4 795 0.24 88.4 143.9 614 0.14

Topped 2.4m 88.7 175.2 506 0.18 78.2 146.6 534 0.12

Controller 9Topped 3.3m 102.2 124.9 818 0.25 84.9 116.8 727 0.14

Topped 2.4m 85.0 142.5 600 0.20 72.0 113.7 633 0.12

Controller 5Topped 3.3m 86.76 122.0 711 0.38 83.4 120.5 692 0.27

Topped 2.4m 89.09 125.0 713 0.39 61.4 118.6 518 0.20

Bottom line:

But, based on the knowledge that we now have, I don’t see how it will be possible to substantially increase profitability of producing fresh market peaches, nectarines and plums in California without some strategic restructuring of the industry to increase the value of the fruit that is sold.

For processing peaches I believe you have the possibility to increase profitability if you concentrate on restructuring the orchards to decrease thinning and harvest costs while continuing to optimize all other management inputs and putting pressure on buyers for increases in price paid for your fruit.

Thanks for your attention!

Questions?

Time

1920 1940 1960 1980 2000

Val

ue p

er a

cre

($/a

cre)

0

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Freestone Peaches

Gross Freestone Peach Returns Per Acre

Year

1920 1940 1960 1980 2000

Acr

es

20000

30000

40000

50000

60000

70000

80000

Cling Peach Acreage

Year

1920 1940 1960 1980 2000

Yie

ld p

er

acr

e (

ton

/acr

e)

0

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10

12

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18

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Average Cling Peach Yields

Year

1920 1940 1960 1980 2000

Va

lue

pe

r a

cre

($

/ac)

0

1000

2000

3000

4000

5000

6000

7000

Cling Peaches

Gross Cling Peach Returns Per Acre

Year

1920 1940 1960 1980 2000

Pric

e p

er

ton

(do

llars

)

0

50

100

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300

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