Kitren Glozer Joe Grant Gregory Lang

Nitrogen Application Timing and Practices in Sweet Cherry Orchards

Goal: Understand how to use Nitrogen to manage vigor, support cropping and high fruit quality

Questions for California N applications:

1. With standard rootstocks, vegetative growth tends to be excessive; a waste of applied N?

2. Excessive soil applications of N, beyond what the tree needs for adequate growth and cropping, can lead to leaching and potential groundwater contamination

3. Sweet cherries often require the use dormancy-breaking chemicals in late winter, which provides additional N

Background: Michigan studies with fall applications of foliar urea increased storage N in spurs and spring spur leaf size

Goal: Understand how to use Nitrogen to manage vigor, support cropping and high fruit quality

Questions for optimizing N applications: When are the seasonal demands for N in sweet cherry? What are the seasonal ‘Best Application Practices’:

When to apply? Forms and rates?

Soil vs. foliar applications? How much Nitrogen is enough? Too little? Too much? When and how to sample and measure tissue N? Which key plant growth and fruiting responses are affected?

Standard Practice: 90 lbs actual N applied postharvest, w/ or w/out dormancy-breaking sprays that also contain N

Mahaleb seedling (vigorous, semi-precocious) in Lodi

Gisela 6 clonal (semi-dwarfing, precocious) in Linden

Mazzard seedling (vigorous, not precocious) in Linden

3 ‘Bing’ orchards: 3 different rootstocks 2 sites, all planted 1998

N Treatments

Actual lb N/acre/year

Jan-Feb Rest-breaking CAN17 or KNO3 ~26 - 54

March Bloom N ~1 April Postbloom urea ~2

June Postharvest CaNO3 45 or 90 (std)

Oct Urea Pre-leaf fall (PLF) 45

Oct-Nov Urea Dormancy-inducing (DI) + ZnSO4 9

Sample Timing Spur bud Shoot terminal bud

Fruiting spur leaf

Shoot leaf Fruit

Late Dormant X X

Bud swell X X April -expanded leaves X X X

Postharvest July X X

Pre leaf fall X X X X

Early dormant X X

Tissues sampled for %N

Nitrogen cycling through the tree into growing points before bud break and into storage tissues before dormancy

Box Plot Explanation

In some cases there are ‘outliers’ (outlying data points) that are beyond the ‘normal’ range of data

Mahaleb April 2010: %N shoot and spur leaves

Shoot leaves

Spur leaves

• Trend is higher spring leaf N with more applied N for both leaf types

• Higher spring leaf N with 90# N PH and fall/dormant applications

• Spur leaf N > shoot leaf N

Shoot leaves: 2.19- 3.40% Spur leaves: 2.59-3.72%

~90-100 ~50 # N/A/yr ~150

Mahaleb Sept 2010: %N shoot and spur leaves

Shoot leaves

Spur leaves

• Trend is not higher fall leaf N with more applied N for both leaf types

• Higher fall leaf N with 90# N PH and fall/dormant applications

• Spur leaf N < shoot leaf N

Shoot leaves: 2.18- 2.46% Highly significant difference among trts Spur leaves: 2.10-2.26% No significant difference among trts

~90-100 ~50 # N/A/yr ~150

Mazzard April 2010: %N shoot and spur leaves

• Similar pattern as in Mahaleb orchard, only with overall higher leaf N values

Shoot leaves: 2.98-2.53% Spur leaves: 3.01-3.78% • Mazzard rootstock

confers more vigor to the scion, possibly due to greater N accumulation

Shoot leaves

Spur leaves

~90-100 ~50 # N/A/yr ~150

Gisela 6 April 2010: %N shoot and spur leaves

• N patterns similar to other rootstocks except for higher leaf N (both types of leaves) with 50# N treatment

• leaf N content similar to that of Mazzard

Shoot leaves: 2.98-2.53% Spur leaves: 3.01-3.78% • It isn’t possible to know

whether this is a site-specific response, or rootstock-specific

Spur leaves

Shoot leaves

~90-100 ~50 # N/A/yr ~150

Mid-Summer leaf N is low ~2.1%, for both spur and shoot leaves

Much higher N (3.6%) is found during rapid fruit growth N status early in the growing season may be a better

indicator of cropping potential, as well as demand Later measurement doesn’t allow for preharvest adjustment

Tissue N Results

Recommended Cherry Leaf %N

(Summer)

Deficient Low Optimum High Excess

< 1.7 1.7-2.1 2.2-2.6 2.7-3.4 > 3.4

Mahaleb TCSA 2010 (treatment effect, 5% level, adjusted for replicate effect)

90PH+CAN+Urea DI 789.9 A 45PH+CAN+Urea DI 775.1 A 45PH+Bloom+Urea PLF 732. 7 A 45PH+Urea PLF 724.3 A 90PH 662.6 AB 45PH+Bloom 544.5 B

90PH+CAN+Urea DI 789.9 A 45PH+CAN+Urea DI 775.1 A 45PH+Bloom+Urea PLF 732. 7 A 45PH+Urea PLF 724.3 A 90PH 662.6 AB 45PH+Bloom 544.5 B

Mahaleb cumulative yield (kg), treatment effect 5% No treatment effect on yield in 2010.

1 45PH+Bloom+Urea PLF 114.2 A 2 45PH+Bloom 108.8 A 3 90PH+CAN+Urea DI 104.3 A 4 45PH+Urea PLF 97.7 AB 5 90PH 97.4 AB 6 45PH+CAN+Urea DI 73.4 B

Mahaleb cumulative yield efficiency (treatment effect at 0.1%; scale x 10) 45PH+Bloom .20 A

45PH+Bloom+Urea PLF .17 AB 90PH .16 AB 45PH+Urea PLF .13 BC 90PH+CAN+Urea DI .13 BC 45PH+CAN+Urea DI .098 C

Mahaleb fruit size, second harvest (treatment effect significant 0.1%)

45PH+Bloom 11.3 A 45PH+Bloom+Urea PLF 11.1 A 90PH 10. 9 A 45PH+Urea PLF 10.7 AB 90PH+CAN+Urea DI 10.2 BC 45PH+CAN+Urea DI 10.1 C

High N (~150#) decreased fruit size

Mazzard fruit size (g) 2010, treatment effect 5%

45(PH)+Bloom N+Urea(PLF) 8.9 A 45(PH)+Bloom N 8.8 AB 90(PH) 8.6 AB 45(PH)+Urea(PLF) 8.5 ABC 90(PH)+CAN(DR)+Urea(DI) 8.3 BC 45(PH)+CAN(DR)+Urea(DI) 8.0 C

45(PH)+Bloom N+Urea(PLF) 8.9 A 45(PH)+Bloom N 8.8 AB 90(PH) 8.6 AB 45(PH)+Urea(PLF) 8.5 ABC 90(PH)+CAN(DR)+Urea(DI) 8.3 BC 45(PH)+CAN(DR)+Urea(DI) 8.0 C

Mahaleb--%First harvest, indicates maturity sooner or later (no treatment effect)

Mazzard cumulative yield (kg); signif = 5% 45PH+Urea PLF 67.8 A 45PH+Bloom 60.1 AB 45PH+Bloom+Urea PLF 59.6 AB 90PH 54.9 AB 90PH+CAN+Urea DI 37.1 BC 45PH+CAN+Urea DI 26.4 C

CAN17 treatments reduced cumulative yield

Mazzard yield efficiency, 2010, treatment effect 5%

45PH+Urea PLF 0.070 A 90PH+CAN+Urea DI 0.066 AB 90PH 0.053 BC 45PH+Bloom+Urea PLF 0.052 BC 45PH+Bloom 0.050 C 45PH+CAN+Urea DI 0.049 C

Mazzard cumulative yield efficiency (kg/cm2); treatment effect 5%

45PH+Bloom 0.060 A 45PH+Bloom+Urea PLF 0.049 AB 45PH+Urea PLF 0.047 AB 90PH 0.046 AB 90PH+CAN+Urea DI 0.027 BC 45PH+CAN+Urea DI 0.019 C

# Shoot breaks and total cm new shoot growth Gisela and Mazzard-- No N treatment effect (2009 or

2010) Mahaleb--2009 Pre-leaf fall urea encouraged vigor in the next spring Vigor was reduced in trees treated with bloom+ petal

fall N Mahaleb—2010: no difference in #shoots, total length

of all new shoots, vigor or crop load

Vegetative Vigor and Reproductive

Yield (lb/tree) in 2009 Mahaleb Gisela Mazzard

90 CaNO3 153 a 51 a 60 a

90 CaNO3, KNO3, urea + ZnSO4 153 a 54 a 55 ab

90 CaNO3, CAN, urea + ZnSO4 149 a 50 a 42ab

45 CaNO3, CAN, urea + ZnSO4 96 b 65 a 31 b

45 CaNO3, pre-leaf fall urea 152a 62 a 68 a

45 CaNO3, bloom 176 a 42 a 65 a

45 CaNO3, bloom, pre-leaf fall 186 a 45 a 60 a

45 CaNO3, postbloom 134 ab 66 a 63 a

45 CaNO3, postbloom, pre-leaf fall 136 ab 62 a 53 a

45 CaNO3, bloom, postbloom, pre-leaf fall 152 a 54 a 61 a

Warm weather in early January – an early ‘wake up call’ We applied lower rates of RBAs to reduce risk In all orchards CAN17 advanced bloom ~ 2 weeks; no

advance with KNO3 (consistent with prior experimental results)

Mazzard and Gisela – CAN treatments advanced bloom and set into a period of

late freeze. (~25% bud death) Reduced yield for Mazzard, not Gisela Mahaleb – yields reduced

CAN17 and KNO3 for Rest-Breaking

Fruit Quality: Mahaleb, 2009-2010

No clear effect on %SS Stem attachment force slightly decreased

in some treatments but overall, stems are attached well and force to remove them is within desirable range

Firmness is slightly affected by treatment, but no clear pattern by treatment is found

Fruit size is not affected

Fruit Quality: Gisela and Mazzard

Some effects of treatment on fruit quality but no clear patterns

Large variation in cropping from tree-to-tree that may affect quality more than treatment does

Nitrogen may not be ‘limiting’ at the rates used, thus no fruit quality or other growing condition is compromised

We appreciate the support of CDFA

California Cherry Advisory Board Pacific Hort

The orchard management contributions and support of our grower cooperators