RT Journal Article SR Electronic T1 Flower Cluster and Shoot Thinning for Crop Control in French-American Hybrid Grapes JF American Journal of Enology and Viticulture JO Am J Enol Vitic. FD American Society for Enology and Viticulture SP 423 OP 426 DO 10.5344/ajev.2004.55.4.423 VO 55 IS 4 A1 Justin R. Morris A1 Gary L. Main A1 Otto L. Oswald YR 2004 UL http://www.ajevonline.org/content/55/4/423.abstract AB Overcropping of French-American hybrid winegrapes changes fruit composition and reduces vine vigor. Simulated mechanized methods of crop control involving entire shoot and cluster thinning were tested for Aurore, Chancellor, and Villard noir cultivars. The experimental design was a 3 x 2 factorial examining three thinning treatments (none, flower cluster, and shoot thinning) and two shoot-bearing positions (count and noncount). The "count" position was determined as shoots from canes and renewal spurs retained during balanced pruning, and "noncount" shoots were those from positions other than count nodes. Thinning treatments had little effect on cluster or berry weights, berries per cluster, or berry composition. Shoot thinning decreased cluster numbers for all three cultivars, but flower cluster thinning affected only red cultivars. The effects of thinning method and shoot position on fruit composition varied with cultivar. These preliminary data indicate that crop control of the cultivars studied can be accomplished by flower cluster thinning and shoot thinning; however, the response to thinning treatments varies with cultivar.