Timing of application of carbaryl used as an apple fruitlet thinner

SummaryApple cvs Bramley, Cox, Discovery and Spartan were treated with carbaryl at a range of times from 80% petal-fall through to mid-June. In Bramley, Discovery and Spartan, the number of fruits per tree was reduced uniformly, irrespective of time of treatment, whereas improvement in fruit size was greatest following treatment at petal-fall and diminished as treatment was delayed. The response of Cox was greatest when fruitlets were on average 12 mm in diameter; treatment at this time also produced the largest fruit.