Effect of paclobutrazol application on growth on mango trees and detection of residues in leaves and soil.
Subhadrabandhu S., Iamsub K., Kataoka I.
Author Affiliation: Department of Horticulture, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand.
Japanese Journal of Tropical Agriculture 43 : 249-253
Abstract : A study was conducted at Kasetsart University in 1991, to analyse the effect of paclobutrazol application by several methods on the vegetative and reproductive growth of mango trees, and to detect its residues in the leaves and soil. Paclobutrazol was applied to 'Nam Dok Mai' as: (1) foliar spray at 1000 p.p.m.; (2) foliar spray at 1000 p.p.m. and covering the soil underneath the canopy with a plastic sheet so that paclobutrazol could penetrate through the leaves only; (3) soil drenching at 8 g/tree; and (4) trunk injection at 400 mg/tree. Soil drenching was most effective in suppressing shoot elongation. Flowering ratio in the trees subjected to all the paclobutrazol treatments was higher than that of the control, but fruit set was only slightly increased by these treatments. Paclobutrazol remained in the soil for up to 11 months when it was applied to soil and for 3 months when applied by foliar spray without soil cover. No residues were detected in the soil following trunk injection, and when paclobutrazol was applied by foliar spray and the soil was covered with a plastic sheet. Levels of paclobutrazol residues were high in leaves subjected to foliar spraying, but not following soil application and trunk injection. In all treatments, no chemical residues were detected in mature fruits.