1	Managing Crop Load for the Upcoming Season S. Kaan Kurtural 2005 Kentucky Fruit and Vegetable Conference and Trade Show 3 – 4 January, 2005
2	Crop Level vs. Crop Load Crop Level = Clusters per vine Clusters per hectare Crop Load = Leaf area required to ripen unit fruit Ratio of yield to prunings
3	CROP CONTROL in grapes Commonly accomplished by dormant pruning Dormant Pruning: Most important annual practice in the vineyard 80% - 90% of annual growth is removed
4	Reasons for Dormant Pruning To control or regulate crop size To achieve a ‘BALANCE’ between Shoot growth and Fruit Production To maintain shape and health of vine Use specific formulas for each variety
5	Balanced Pruning measures Relation between Previous season’s growth & Ability to cope with Fruiting Stress Severity of pruning established with Balanced Pruning formula (BPF)
6	Case for French-American hybrids Many fruitful shoots from non-count positions Therefore balanced pruning does not adequately control cropping levels
7	Cluster thinning adjusts Cropping to achieve a better balance between vegetative capacity and fruiting in French-American hybrids (fruiting on non-count shoots)
8	Rule of thumb Small clustered cultivars No need for cluster thinning Large clustered cultivars and varieties with fruitful base buds One cluster per shoot Timing is critical Most benefit if applied pre-bloom
9	Benefits of Cluster thinning Immediate Increased sugar accumulation in fruit Advanced maturity of crop Increased cane maturity Decreased cane die-back Long term Increased vine vigor following season
10	BALANCED CROPPING Balanced Pruning Pruning weights Leaf area Vegetative Capacity Cluster thinning Number of berries per cluster Number of clusters per vine Reproductive capacity
11	CROPLOAD Balanced Cropping Measured as RATIO: REPRODUCTIVE GROWTH VEGETATIVE CAPACITY Reproductive Growth (crop weight in pounds) Vegetative Capacity (Pruning weight in pounds) Cropload = Crop yield ÷ Pruning weights
12	UNBALANCED CROPPING Overcropping : Too many clusters per leaf area Undercropping : Too few clusters per leaf area
13	Overcropping Symptoms Immediate (same season) Reduced sugar accumulation in the fruit Reduced berry size Poor cane maturation Increased cane dieback Decreased primary bud cold hardiness
14	Overcropping Symptoms Long Term Reduction in vine vigor Reduced shoot growth next season Reduction in vine size Reduced leaf area, pruning weights Reduction in cropping potential Reduced PROFITABILITY
15	Undercropping Symptoms Immediate symptoms Increased sugar accumulation in fruit Increased cluster size Increased vegetative growth in canopy Long term Reduced fruitfulness due to vegetative imbalance in prior year Reduced PROFITABILITY
16	How to Achieve Vine Balance Practice Balanced Cropping Balanced pruning + Cluster thinning Before implementation: Vine vigor (size) must be measured
17	Vine vigor = Previous year’s Vine Size
18	Balanced Pruning example
19	Rule of thumb Retain 4 to 6 nodes per foot of cordon In 8’ spacing 32 to 48 (max) nodes per vine
20	Vine size vs. Cropload
21	Balanced cropping example from the Midwest (Kurtural et al., 2003; 2004a; 2004b;2004c) French-American hybrid Balanced pruning does not provide adequate crop control
22	Materials and Methods Own rooted ‘Chambourcin’ grapevines Pruning treatments 15 + 15 20 + 20 25 + 25 Cluster thinning treatments (post-fruit set) 1 cluster/shoot (1 cluster shoot) 2 clusters/shoot (1.2 clusters/shoot) 2+ clusters/shoot (1.5 clusters/shoot)
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33	Take Home Message Large clustered cultivars grown under long – warm season climate Use balanced pruning of 15 to 20 nodes per pound of prunings Follow by post-set Cluster thinning to 1 to 1.2 cl/shoot Yield not exceeding 6 T/A Results in optimum vine size no less than 0.2 lb/foot of row.
34	Estimating Yields Why estimate yield? How much production If overcropping or undercropping Growers interested in trying this method should begin collecting data this season This is an ESTIMATE of the YIELD
35	Effect of Yield on Crop Maturity
36	Crop estimation formula (Imed E.Dami, OSU 2004) PY = (ANV x NC x CW) / 2000 PY = Predicted yield ANV = actual no. of vines per acre NC = No. of clusters per vine CW = Cluster weight in lb
37	What the grower needs to measure (1) Actual number of bearing vines per acre Row and vine spacing 6 x 9 = 807 vines to the acre BUT…… Missing vines due to disease, winter injury, equipment damage If 5% of the 807 vines are missing, no. of bearing vines/acre is 767
38	What you need to measure (2) Number of clusters per vine Depends on how many nodes retained and if cluster thinning is practiced Count clusters pre-bloom as they are not obstructed by leaves, shoots etc. This information is useful to the vintners as well, to plan on how many to purchase In small – plot vineyards (1-3 acres) pruned uniformly, only 4% of the total vines need to be counted In practice, a min. of 20 vines is counted
39	What you need to measure (3) Cluster weight Component of yield that varies the most from year to year Wet weather during bloom, dry summers, irrigation, fertilizers, diseases insects, cultural practices affect cluster weight Sample at harvest from the same vines cluster counts were taken MAINTAIN RECORDS OF CLUSTER WEIGHTS EACH YEAR
40	Crop estimation of Chambourcin Spacing = 8 x 9 or 605 vine per acre Missing vines = 5% or 31 vines Actual number of bearing vines= 605-31 = 574 Cluster count = 45 clusters/vine Average cluster weight = 0.42 lb Predicted Yield = (574 x 45 x 0.42)/2000 PY = 5.42 T/A
41	Average cluster wts in lb of common grape varieties
42	Average cluster wts in lbs of common grape varieties
43	Average cluster wts in lbs of common grape varieties
44	Questions