Vol. 82 No: 1

Title:
Effects of paclobutrazol applied to tree bark on performance of sweet cherry and apparent soil residue

Author:
T. JACYNA

pp: 19-24

Abstract:
Two-year-old ´Bing` sweet cherry trees, planted at a density of ca. 1,000 trees ha<sup>-1</sup> were treated with paclobutrazol (Cultar™). Paclobutrazol was dissolved in ´Surfactant WK` and brush-painted onto tree trunk bark in bands 10, 20, 30 or 40 cm wide.A standard rate of 15 mg paclobutrazol cm^-2 tree trunk cross-sectional area (TCSA) was applied in all chemical treatments. On average, all paclobutrazol treatments reduced shoot growth to 55.5% and 21.1% of control trees in the year of application and in the next year, respectively. In both years, TCSA, total shoot extension growth, shoot length, and tree height were visibly inhibited by paclobutrazol. One year after chemical application, the number of water sprouts diminished more than in the previous year. Paclobutrazol advanced the time of flowering compared to untreated trees. In most cases, there were no significant differences in the characteristics examined among all paclobutrazol treatments. Bio-assays using broad beans in the soil taken from around the treated trees, 22 months after the application of paclobutrazol, showed that growth of these indicator plants, was reduced to 99.8%, 90.5%, 75.6% and 81.9% of control values in soil from trees with treated trunk bark bands 10, 20, 30 or 40 cm wide, respectively. Brush application of paclobutrazol to a narrow band (10 - 20 cm-wide) of tree trunk bark may eliminate chemical residues in the soil, while securing effective growth control in young sweet cherry trees.

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