Abstract
1. Influence of defoliation in the previous fall on the thinning effect of Peach-thin was tested on peach trees (Cultivar Hakuho, ten years old in the first year) in three successive years. One half each of three trees was defoliated in late September or early October, while another half was remained undefoliated. 200ppm solution of Peach-thin was sprayed on both parts of each tree two or three days after full bloom, and fruit setting was counted 25 days after full bloom. Three years′ result showed that there were no significant differences in thinning effect of spray between defoliated and undefoliated parts of the trees.
Fruit setting percentages of the sprayed parts on the partially defoliated trees as awhole were, however, significantly lower than that of the similar trees which were never defoliated.
2. Influence of severity of pruning on the thinning effect of Peachthin was tested on Hakuho trees (six years old in the first year) in two years. Three trees were heavily pruned, while other three trees were moderately pruned. 200 and 400ppm solutions of Peach-thin were sprayed on these trees and fruit seting was counted in the same way as in the above mentioned experiment. Two years′ result revealed that thinning effect of spray was severer on heavily pruned trees than on the moderately pruned ones. Percentage of fruit setting was reduced approximately in the same rate in both unsprayed and sprayed branches, respectively, by the heavy pruning
