ISHS Acta Horticulturae 199: II International Workshop on Temperate Zone Fruits in the Tropics and Subtropics
BREAKING DORMANCY OF APPLE TREES WITH CHEMICALS |
| Author: | J.L. Petri |
| Abstract:
Since 1970 apple production has greatly expanded in southern Brazil to cover approximately 20 000 hectares. As a result, the chilling requirement of apple is not completely satisfied, especially with respect to the cultivars more commonly grown in Santa Catarina: Gala, Fuji, Golden Delicious, Granny Smith and Belgolden. It is necessary to use rest-breaking chemicals under these conditions, to avoid abnormal bud break and low yield. Trials were carried out over a 12-year period to evaluate chemical treatments, concentrations, time of application and environmental factors affecting the breaking of dormancy of apple trees. Commercially, application of mineral oil at 4–6% plus DNBP (dinitro-butyl-phenol) at 0.13% to 0.2% was most efficient, as it broke dormancy and also controlled red mites sp. Further, more it can be part of the winter phytosanitary control program. The time of application affected the degree of lateral bud break, as well as the flowering date, which was sometimes advanced by more than 25 days, particularly in mild winters. Mineral oil at 4% plus DNBP at 0.12% induced lateral bud break rate above 40%, whereas bud break in control trees was below 6%. Lateral bud break was also affected by DNBP concentration. | |
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