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Abstract
Foliar copper deposits varied by a factor of 5-fold when copper was applied with an airblast sprayer at a rate of 935 liters/ha (100 gallons/acre) to trees of apple (Malus domestica Borkh.). Higher deposits were recorded as tree size decreased. Chemical deposit was related inversely to percentage of light penetration through the canopy.
Abstract
Shading of nectarine [Prunus persica (L.) Batsch] scaffold limbs 45-58 days after full bloom caused seed discoloration and fruit abscission. Shading of peach [Prunus persica (L.) Batsch] scaffold limbs from 31-41 days after full bloom caused greater fruit adscisson than shading from 11-21 or 21-31 days after bloom. The photosynthetic inhibitor, 3-tert-butyl-5-chloro-6-methyluracil (terbacil), applied to whole trees 35 days after full bloom induced fruit abscission. Terbacil at 500 ppm or higher caused excessive thinning. Fruit size was larger than hand thinned fruit, since overthinning occurred. Fruit color, soluble solids, and firmness of fruit from the 500 ppm treated trees were similar to fruit from hand thinned trees. No leaves abscissed, but marginal chlorosis occurred on less than 30% of the leaves at harvest. Flower bud numbers per cm of terminal length were similar to the hand thinned trees, but much greater than unthinned trees. Residue analysis of fruit at harvest from the 500 ppm terbacil treatment revealed 0.07 ppm in the fruit.