COMPARISON OF FRUIT THINNING SPRAYS ON FOUR APPLE CULTIVARS

B.E. Windle, H. van Dam
The crops from trees sprayed with the herbicide terbacil, ethephon, NAA and carbaryl and combinations of these chemicals with mineral oil at various times after full bloom were compared with unthinned control trees of the cultivars Red Delicious, Jonathan, Granny Smith and Golden Delicious.

Single tree plots were sprayed by hand gun (2 700 L/ha) and assessed at harvest by comparing the distribution of fruits over eight size classes.

Terbacil at 200 ppm was effective as a fruit thinning spray but caused temporary leaf damage and some leaf drop. Treatments that included a carbaryl spray increased the proportion of larger size fruits. A single spray mixture of carbaryl (1 200 ppm) and NAA (10 ppm) increased the proportion of Golden Delicious apples in commercial sizes by 36%. Some thinning sprays reduced the weight of crop harvested in commercial sizes on Red Delicious and Granny Smith.

Windle, B.E. and van Dam, H. (1989). COMPARISON OF FRUIT THINNING SPRAYS ON FOUR APPLE CULTIVARS. Acta Hortic. 240, 229-232
DOI: 10.17660/ActaHortic.1989.240.42
https://doi.org/10.17660/ActaHortic.1989.240.42

Acta Horticulturae