Xinyi Zhang

Date of Graduation

Summer 2013


Master of Science in Plant Science (Agriculture)


College of Agriculture

Committee Chair

Martin Kaps


Norton, canopy management, shoot thinning, shoot positioning, leaf removal, summer lateral removal, fruit quality, wine quality

Subject Categories

Plant Sciences


Norton (Vitis aestivalis Michx) is a vigorous grape cultivar that grows a dense canopy. This leads to shade in the fruiting zone that negatively affects fruit quality. Canopy management is thought to reduce canopy density and overcome this negative effect. Shoot thinning, shoot positioning, leaf removal, and summer lateral removal were done in various combinations of five treatments. Three of the treatments with opened canopies increased light and ventilation in the fruiting zone. Total fruit weight per vine and average cluster weight were not affected. Neither were juice soluble solids, pH, potassium, and malic acid. Cane pruning weight per vine was not consistently altered by treatment. Titratable acidity of juice was affected, showing a decrease with leaf or leaf and summer lateral removal. These practices would be beneficial in growing Norton because of its potential for high acidity at harvest. Wine pH, titratable acidity, and potassium were not affected; however, all were acceptable in the finished wine. Visual observation showed that the dense canopy control was prone to rot, and the leaf and summer lateral removal treatment was prone to fruit sunburn. Leaf removal is likely a better choice than both leaf and summer lateral removal. Leaf removal is faster to implement and there is less potential for fruit sunburn from excessive defoliation that comes from both leaf and summer lateral removal.


© Xinyi Zhang

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