The effects of paclobutrazol and daminozide on the growth and yield of cider apple trees

Abstract

SummaryThe effects of soil applications (1, 2 or 4 kg a.i. ha-1 to give 0.25, 0.5 or 1.0 g a.i. per tree) or foliar sprays (1000 or 2000 mg l-1 to give 2 or 4 g a.i. per tree) of paclobutrazol (PP 333) were compared with those of foliar daminozide (Alar) sprays (2000 mg l-1 to give 4 g a.i. per tree) on bush cider apple cv Michelin for two years. Extension shoot growth was significantly reduced in the year of application (Year 1) by foliar paclobutrazol and daminozide sprays, and in the following year by the foliar and high-rate soil-applied paclobutrazol but not by daminozide. Foliar applications of paclobutrazol reduced leaf size and darkened leaf colour, delayed flowering and enhanced fruit set. Yields were not affected by any treatment.