UPTAKE, TRANSLOCATION, PERSISTENCE AND FATE OF AZADIRACHTIN IN ASPEN PLANTS (POPULUS-TREMULOIDES MICHX) AND ITS EFFECT ON PESTIFEROUS 2-SPOTTED SPIDER-MITE (TETRANYCHUS-URTICAE KOCH)

A commercial neem formulation containing azadirachtin-A (AZ-A) was app lied to the soil around the root system of potted aspen (Populus tremu loides Michx.) plants. The uptake, translocation, persistence and diss ipation of the chemical in the plants were studied. The effect of foli ar residues of AZ-A on twospotted spider mite (Tetranychus urticae Koc h) populations was also evaluated. The compound was taken up by the ro ot system within 3 h and translocated in the stem and foliage within 3 days, confirming that AZ-A is systemic. The peak concentrations (mu g /g, fresh weight) of AZ-A occurred at 10 days posttreatment, and were distributed in roots, stem and foliage in the ratio of 8.1:1.0:2.3, re spectively. The rate of dissipation of AZ-A from the matrices was mode rately rapid, and the residual concentrations on the last day of sampl ing (50 days post-treatment) in roots, stem and foliage were in the ra tio 2.7:1.0:1.2, respectively. Control of mites by AZ-A residues in fo liage was statistically significant, and the bioactivity declined with in 30 days. The final residue of AZ-A in the soil after 50 days was ab out 25% of the initial value, with a half-life of dissipation of about 26 days.