ISHS Acta Horticulturae 636: XXVI International Horticultural Congress: Key Processes in the Growth and Cropping of Deciduous Fruit and Nut Trees
THINNING OF FUJI AND GALA APPLE WITH LIME SULPHUR AND OTHER CHEMICALS |
| Authors: | S. Guak, M. Beulah, N.E. Looney |
| Keywords: | chemical thinning, lime sulphur, ammonium thiosulphate, carbaryl, Accel®, fruit quality, return flowering, Malus x domestica |
| Abstract:
Fuji and Gala/M9 slender spindle apple trees were treated with lime sulphur (LS) at 85% full bloom at rates up to 4%. Some Fuji trees were also treated with carbaryl or Accel® when average fruit diameter was 12 mm. With both cultivars, LS reduced crop load linearly with rate. For Fuji, the highest LS rate was about as effective as the 1.6% ammonium thiosulphate (ATS) commercial control in terms of reduced fruit set, increased proportion of fruiting sites with a single fruit, and increased fruit weight at harvest. For Gala, 3-4% LS also showed positive thinning effects but proved less effective than the ATS control. LS treatments caused Fuji fruits to be slightly longer than the untreated control but other fruit quality characteristics at harvest were largely unaffected. After 3 or 4 months of 1°C storage, firmness of Gala was slightly reduced by LS treatment but juice soluble solids and acidity were unaffected. 4% LS induced less leaf burn than 1.6% ATS. For Fuji, post-bloom carbaryl further reduced crop load without any interaction with bloom-time LS whereas Accel® had little or no effect on crop load. Return flowering was slightly increased by LS in both cultivars and post-bloom carbaryl further enhanced flowering of Fuji. | |
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