ISHS Acta Horticulturae 179: V International Symposium on Growth Regulators in Fruit Production
SOME EFFECTS OF PACLOBUTRAZOL ON GROWTH AND FRUITING OF APPLE, PEACH AND CHERRY. |
| Author: | L.J. Edgerton |
| Abstract:
Significant reduction in vegetative growth has been obtained on peach, sweet cherry and young apple trees with soil applications of paclobutrazol either when injected below the soil surface in the root zone or applied around the tree trunk at the soil line. With older apple trees and those having a trunk diameter of over 15 cm little or no response is obtained the first season following the soil surface application, even when placed around the tree trunk. Second year responses occur, but are unpredictable. Foliar sprays on apples starting with a pre-bloom application and following with two or three post bloom applications for a total of 500 to 1000 ppm have been effective in checking vegetative growth, and enhancing flowering and yield on mature apple trees. This treatment has provided growth control of 40 to 60% of the controls. Similar paclobutrazol applications, both soil and foliar sprays on sweet cherry, sour cherry and peach reduced shoot growth the first year and increased flowering and fruiting the following year. With 5-year-old 'Van' sweet cherry trees the yield in 1984 from the soil drench around the tree trunks was three times the controls, and nearly twice the controls for the July 1983 foliar sprays. Yield increased for 'Redhaven' peach in 1984 and 1985 while significant, were not as great as for the sweet cherry. The increased yield with 'Redhaven' peach appears to be a composite of increased flower bud density, improved flower bud survival during the dormant season, and increased fruit size at harvest. With sweet cherry, on the other hand, the increased yield on treated trees is primarily the large increase in flowers initiated on the spurs and shoots. | |
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