YIELD AND GRADING RESULT OF ‘AROMA’ APPLES AS INFLUENCED BY PRUNING TREATMENTS

‘Aroma’ trees, planted in 1972 at the Agricultural University of Norway, were pruned once a year, in late January, April, July, and October, respectively, during 1980–1986. Trees in the control plots were left unpruned during the same years. In 1983–1985 the fruit yield from the individual plots was graded separately. In Norway the minimum size for Class I fruit is 60 mm for this cultivar, and the proportion of fruit below and over this limit was studied for the different treatments. Unpruned trees from the control plots had the highest total yields. Only about 50% of the fruit from this treatment, however, satisfied the minimum requirements for Class I. Trees pruned in late April had the second highest total yield and the highest yield of Class I fruit. Pruning in late July gave the lowest yield of Class I fruit, slightly lower than the unpruned control trees and trees pruned in January. The tendency to biennial cropping was most pronounced in the unpruned control and in the plots pruned in July.