The influence of paclobutrazol on the growth and cropping of sweet cherry cultivars. I. The effect of annual soil treatments on the growth and cropping of cv Early Rivers

Abstract

SummaryAnnual treatments with paclobutrazol to the soil beneath cv Early Rivers sweet cherry trees significantly inhibited the growth of new extension shoots. An application of 1.6 g a.i. per tree in March 1981, followed by 0.8 g a.i. per tree in March 1982,1983 and 1984 sustained almost complete inhibition of extension growth on young trees on either Colt or FB 22 (a sibling of Colt) rootstocks. On treated trees, crown volume at the end of 1984 was only one-third that of unsprayed control trees. The density of floral bud production was doubled in 1982 and 1983 and trebled in 1984 on the treated trees, and the treatment also increased the number of floral buds per cluster and the number of flowers per floral bud. Frost damage to floral buds was reduced by more than 20% in the winter of 1981/82, as was the damage to blossoms by spring frosts in 1983. The time of blossoming was slightly advanced by the treatment. The percentage final fruit set was not influenced by the treatments in 1982 and 1983, but was halved on treated trees in 1984. Yields per tree were increased by the treatment in 1982 but reduced in 1983 and 1984; however, yields m−3 of tree crown were increased on treated trees by 92% and 69% in 1983 and 1984 respectively. Larger fruits were harvested from treated trees in all three years of the experiment.