Dissipation kinetics of azadirachtin in some forest matrices and its systemic translocation in conifers for spruce budworm control

Abstract

Field microcosm studies were conducted to investigate the deposition, persistence, translocation and bioactivity of the botanical insecticide azadirachtin‐A (AZ‐A) in young spruce trees. The deposition and persistence of AZ‐A in aspen foliage, forest soil and litter were also studied. AZ‐A residues in the different matrices were monitored at intervals of time after spray application of Neemix^® 4.5 formulation at 100 g AZ‐A in 2.3 L/ha. The dissipation half‐lives in the matrices ranged from 16.9 to 33.6 h. AZ‐A was translocated and concentrated in the growing parts (especially the shoots) of spruce trees, after treatment by trunk injection (Tl), basal bark painting (BBP) and foliar painting (FP) of the Neemix 4.5 formulation. Systemically translocated and accumulated AZ‐A residues in the shoots after Tl and FP were found to be effective against spruce budworm (Choristoneura fumiferana Clemens.) larvae. Results suggest that Tl may be a useful way of using neem insecticide to protect high value trees from insect pests.

Key words:

• azadirachtin‐A
• persistence
• DT₅₀
• foliage
• soil
• litter
• trunk injection
• basal bark painting
• foliar painting
• translocation
• systemic action
• residual toxicity