THE RESPONSE OF HOSUI JAPANESE PEAR TO TIME OF HAND THINNING AND CHEMICAL THINNING AGENTS

Changes in fruit size in response to flower and early fruitlet thinning were measured on the Japanese pear (Pyrus pyrifolia Nakai) cultivar 'Hosui'. All trees were thinned to a standard crop load after the final fruit set. Heavy flower thinning reduced initial fruit set and resulted in a significant increase in fruit size. The efficacy of chemical thinning agents, used commercially on other pitfruit, was also determined on this cultivar. Carbaryl and naphthalene acetic acid (NAA) did not reduce fruit set, but NAA did increase the proportion of fruit with calyx disorder. Ethephon reduced fruit set, but did not increase fruit size. NAA and ethephon treatments did not influence the harvest maturity or occurrence of post-harvest disorders.