ISHS Acta Horticulturae 146: International Workshop on Controlling Vigor in Fruit Trees
USE OF BIOREGULATORS TO CONTROL VEGETATIVE GROWTH OF FRUIT TREES AND IMPROVE FRUITING EFFICIENCY |
| Author: | Max W. Williams |
| Abstract:
The growth retardant paclobutrazol was applied to the soil at the base of 'Delicious' and 'Golden Delicious' apple trees. One application per tree in 1979 controlled terminal shoot growth for several seasons. There was little or no effect of the chemical on fruit size. Yield increased on treated trees and the fruit colored earlier because of the increased sunlight on the fruiting spurs. The high rates of paclobutrazol caused no phytotoxicity but had an adverse effect on 'Delicious' fruit shape and stem length. A complete reversal of the adverse effects of the high rates on fruit shape was obtained by applying Promalin at 25 ppm. Promalin is a commercial product containing GA4+7 and 6-BenzylAdenine. By reducing excessive terminal growth, tree efficiency is increased. Treated trees are more consistent in annual flower production and cropping. | |
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