The influence of KJ, CuSO4, and Mg(ClO3)2 on defoliation and subsequent frost resistance and growth of apple trees in nurseries

Abstract

In most cases 2-year-old trees of 3 cultivars responded better to defoliants than 1-year-old ones. Spraying with defoliants on September 25 - 28 was more effective than spraying 10 days earlier. There was also more bark injury in the autumn, and more frost injury on trees defoliated on the ealier date. Mg(ClO3)2 seemed to be the best defoliant but markedly decreased the frost resistance of Mcintosh trees. Defoliants investigated may be applied to limited extent to 2-year-old trees but not to 1-year-old ones.