Limited occurrence of foliar-, root-, and seed-applied neem seed extract toxin in untreated plant parts

A 1% solution of neem ( Azadirachta indica A. Juss.) seed extract used against Liriomyza trifolii (Burgess) failed to increase the toxicity of untreated chrysanthemum foliage ( Dendranthema morifolium (Ramat) Tzvel.) positioned above or below sprayed foliage. Untreated bean ( Phaseolus limensis MacF.) leaves opposite to leaves painted with 0.4% extract were not as toxic to L. trifolii as painted leaves. Foliage on chrysanthemum cuttings that were root-dipped in 0.4% extract was toxic to leafminers but subsequent new foliage was not. Bean seeds soaked in 4% extract for 6 h germinated to seedlings which were not significantly more toxic to L. trifolii than untreated seedlings. In contrast, drenching the germination medium with 0.8% extract resulted in seedlings from which no leafminers were reared. Results indicate that complete coverage is required for maximum efficacy of neem seed extract foliage sprays against L. trifolii . Treatment of cuttings and seeds with extract has limitations. Instead, drenches to growing media are recommended as more efficacious.