In laboratory studies there was observed no positive effect of azadirachtin on PVY^N retention in Myzus persicae (Sulz.) which, having contracted the pathogen, were starved and next they were feeding on Physalis floridana test plants. Aphids feeding on protected plants retained active virus for 64 minutes, which was even longer than aphids feeding on unprotected test plants (16 min.). A positive effect of azadirachtin was found in aphids feeding directly after contracting the virus. In two study series only, out of a total of 12, further (the third and fourth) plants were infected out of 10 successively inoculated in the series. In all the other series only the first plants were infected. In some non-protected series also even further plants were infected (the fifth, sixth and even eighth out of 10 inoculated plants). Similarly the total plant infection in the non-protected combination was higher (15%) than in the protected one (5%).

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