MANIPULATION OF BLOSSOM DENSITY AND THE EFFECTS OF ETHEPHON THINNING OF GOLDEN DELICIOUS

The effect of thinning Golden Delicious trees with ethephon at 350 ppm at balloon blossom or at 40 days after full bloom (AFB) was tested on three blossom density categories.
Blossom density was manipulated to 3, 5 or 7.5 blossoms/cm² of trunk area by pruning off blossom in early spring.
The thinning levels achieved with ethephon, expressed as percentage of fruit thinned (numbers set per 100 blossom clusters) or fruit set per cm² of trunk area, were independent of blossom-density.

Natural shed in the control trees was significantly influenced by blossom-density.
Although the largest percentage shed was in the highest blossom-density category, the converse was true of the fruit set per cm² of trunk area, where the higher number of buds per cm² of trunk area more than compensated for the heavier shed.

Mean fruit weight was a reflection of thinning success with only four of the ethephon thinned treatments achieving the required 149 g per fruit average.

It was concluded that pruning should not be based on removing flower buds to improve thinning of Golden Delicious when ethephon is used as a thinner.

V International Symposium on Growth Regulators in Fruit Production

K.M. Jones, T.B. Koen

https://doi.org/10.17660/ActaHortic.1986.179.108