Bioefficacy of Insecticides Against Peach Leaf Curl Aphid, Brachycaudus Helichrysi (Kaltenbach) in Punjab

The studies on bioefficacy of insecticides conducted at Punjab Agricultural University, Ludhiana from 2006 to 2008 revealed that imidacloprid (0.008%), thiamethoxam (0.006 and 0.008%) and acetamiprid (0.008%) were significantly more effective against nymphs and adults of Brachycaudus helichrysi (Kaltenbach) in all the combinations of treatments (pre-flowering+flowering+pea stage, pre-flowering+pea stage, pre-flowering or pea stage) as no population was recorded 5 days after application compared to untreated control (19.4 aphids/leaf). Dimethoate at all doses (0.048, 0.1 and 0.12%) was less effective and three applications (pre-flowering + flowering + pea stage) of imidacloprid (0.008%), thiamethoxam (0.006 and 0.008%) and acetamiprid (0.008%) had no curling of leaves. As the frequency of application reduced the per cent curled leaves increased and the single application made either at pre-flowering and pea stage had 58.4–74.2% curled leaves compared to untreated control (72.3%). The data on fruit set was quite variable but were significantly more than the untreated control. The trees treated with imidacloprid, acetamiprid and thiamethoxam (each 0.004, 0.006 and 0.008%) were observed to be visited by honey bees either on same day or second day after spray while dimethoate and oxydemeton methyl were found to be highly toxic as the honey bees avoided the trees even on 2^nd day after spray.