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80 W i n e s & V i n e s A P R i L 2 0 1 4 WineEast occurred after the first killing fall frost, and 3) winter harvest, which corresponded to the typical commercial harvest for ice wine when the temperature dropped to 18°F. Results As expected, grapevines with a high clus- ter count had higher yields but lower clus- ter weight than those with a low cluster count (see table above). However, cluster thinning did not affect berry weight in any season. It is concluded that the yield in- crease was the result of increased cluster number but not cluster weight. Harvest date did not affect yield except for winter harvest, when yield dropped due to berry dehydration. Vine size was also affected by cluster thinning but not harvest date. In fact, prun- ing weight declined over the years in vines with high cluster count, an indication that the vines were overcropped or out of bal- ance. However, vine size was optimum and did not decline in vines with 40 clusters. Crop-load ratio was also optimum and aver- aged a value of 18 over the five-year dura- tion of the study. Based on crop weight, pruning weight and crop-load ratios, it is concluded that the 40-cluster treatment produced balanced vines. The 40-cluster treatment had higher soluble sugars and pH values than the 60-cluster treatment in three of five years. The changes in fruit composition associated with cluster thinning have been reported in other grape varieties and are a typical response of advancing fruit maturity by reducing the crop level and vice versa. Additionally and expectedly, as harvest was delayed, the soluble sugars and pH increased and titratable acidity decreased. These responses were also generally attrib- uted to more ripe fruit with delayed harvest, which typically produces fruit with high Brix and pH and low titratable acidity. Freezing tests were conducted in the laboratory to determine the effect of clus- ter thinning and harvest date on bud cold hardiness. Over three years, we found no negative impact of the treatments on cold hardiness. We confirmed our lab find- ings following two actual freezing events during the study period. The coldest temperatures recorded in the Vidal block were -8° F in 2004 and -18° F in 2009. Bud injury was assessed following both cold events and ranged between 34% and 57%; however, we found no differences among treatments. In summary, the yield and fruit composition responses to cluster thinning and harvest date were typical of those observed in other grape varieties. We concluded that the 40- but not the 60-cluster treatment produced optimum vine size and crop load thus balanced vines. Furthermore, hang time in Vidal for ice wine production in the northeastern United States and Canada improves fruit composition but has no adverse impact on bud cold hardiness as long as recommended practices of balanced Grapegrowing Treatment Yield (tons/ acre) Vine size (pruning weight [lbs] / feet of cordon) Crop load Total soluble solids (Brix) pH Titrat- able acidity (%) Bud injury after -18°F (%) ClusTEr THinning 60 clusters/vine 7.4* 0.18 24* 22.7 3.21 0.99 49 40 clusters/vine 6.5 0.21* 18 23.4* 3.24* 0.98 39 HarVEsT DaTE Normal harvest 7.3* 0.20 23 21.4 3.14 1.03** 41 Fall harvest 6.8* 0.21 21 22.9* 3.22* 0.99* 45 Winter harvest 6.0 0.21 -- 25.2** 3.38** 0.82 46 * and ** indicate statistical differences among treatments within columns. 716.542.3000 • WWW.NIAGARALABEL.COM digital printing flexo printing screen printing embossing hot & cold foil specialty papers Trellis Supplies • Notched Metal Post, Wood • Anchors • Wire • Tools • Gripples • Dura-Line Training & Tying Supplies •Tree-fix • Wire ties • AgLoc • Klip-on • Grow Tubes • Training Stakes • Tying Products Wildlife Control • Bird netting • Side Applied Netting • BirdGard • Scare Devices • Deer Fence & Deterrents Spring Pruning and Tying Supplies FINGER LAKES TRELLIS SUPPLY BUY ONLINE! www.fingerlakestrellissupply.com 315-904-4007 4041A Railroad Ave. info@fingerlakestrellissupply.com Williamson, NY 14589