Fruit thinning by a postbloom spray of 1-naphthyl n-methycarbamate (carbaryl) or naphthaleneacetic acid (NAA) was not increased by a previous full bloom spray of gibberellin A 4+7 (GA 4+7 ) plus 6-benzylamino purine (BA). Chemical thinning generally increased return bloom but not fruit size. GA 4+7 + BA consistently increased the fruit L/D ratio, showed no effect on fruit size or seed number, and these responses were not altered by the chemical thinners. Overall responses were similar for trees treated either one or 2 consecutive years with GA 4+7 + BA and chemical thinners. Response to treatment was similar among strain of ‘Delicious’ and did not vary with tree age.
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Greene et al. (1985) studied this question.