Promalin improves the shape of Delicious apples in Victoria

Abstract

Results of two experiments and nine orchard trials over three seasons at eight fruit growing districts have shown that fruit shape of Richared, Lalla, Starking, Hi-Early and Common Delicious apples can be improved by applications of the commercial formulation of N-(phenylmethylkl H-purin-61 - 1 amine plus gibberellins A, + A, (Promalin). Promalin at 25 ppm significantiy increased both fruit length: diameter ratio and prominence of calyx lobes. These fruit were considered to have a more characteristic shape and thus said to be more 'typey'. Response varied between strains, and applications during early stages of flowering were more effective than applications after full bloom. The spraying of Promalin with a hand gun caused heavy overthinning and retention of many small fruit on the tree. Applications with air blast spray equipment at spray volumes of 750-1 100 I/ha gave good results. Some air blast applications induced mild fruit thinning, and in several cases seed number was reduced and stem length increased.