ISHS Acta Horticulturae 772: XXVII International Horticultural Congress - IHC2006: International Symposium on Enhancing Economic and Environmental Sustainability of Fruit Production in a Global Economy
DEVELOPMENT OF A SAFER AND NEW BUD-REST BREAKING AGENT FOR 'GOLDEN DELICIOUS' APPLES GROWN UNDER MARGINAL CLIMATIC CONDITIONS |
| Authors: | M.S. North, F.W.R. Gonggrijp |
| Keywords: | delayed foliation, adjuvants, oil |
| Abstract:
To reduce the incidence of growth abnormalities associated with insufficient winter chilling, most of the apple (Malus domestica Borkh.) trees grown in the Western Cape, South Africa, receive applications of a chemical bud-rest breaking agent (RBA) at the end of winter. Less hazardous RBA’s are essential to replace products that are currently commercially used. Nitrogen based bud-rest breaking agents tend to be effective only at relatively high concentrations and imbalances between reproductive and vegetative bud-burst may occur. Mixtures of an inorganic and organic nitrogen source, with penetrant and/or humectant adjuvant/s, petroleum or vegetable oils were evaluated against the commercially used control (DormexR/oil) on mature ‘Golden Delicious’ apple trees at two sites over five seasons. A formulation that contained 9.38% N from a mixture of 4.8% v/v choline chloride, 6.6% v/v GAN with 1.5% v/v PartnerR and 3% v/v NPX was just as effective in promoting bud burst and improving fruit set and fruit size as the commercial control. | |
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