Chemical fruit thinning of two early-season apple cultivars, Discovery and George Cave

Abstract

SummaryBoth 2100 ppm carbaryl and 500 ppm M&B 25105 (n-propyl-3-t-butylphenoxy acetate) applied when the average fruitlet diameter was 12–14 mm reliably reduced the number of cv Discovery fruitlets retained to harvest and increased the proportion of large fruits. Ethephon at 150 ppm was also effective in thinning fruitlets but inhibited fruit growth. Both 300 ppm ethephon, applied at flowering, and 2100 ppm carbaryl, applied when the average fruitlet diameter was 10–14 mm, thinned cv George Cave fruitlets and increased average fruit size.