EFFICACY OF SOME INSECTICIDES, ADJUVANTS AND THEIR MIXTURES FOR CONTROLLING THE WHEAT APHID, Schizaphis graminum Rondani (Hemiptera: Aphididae) AND ONION THRIPS, Thrips tabaci ON WHEAT PLANTS

Document Type : Original Article

Authors

Plant Prot. Dept., Fac. Agric., Zagazig Univ., Egypt

Abstract

Field experiments were conducted to evaluate the effect of three insecticides individually and in combination with two adjuvants (Tween 80 and Sylgard 309) for control of the wheat aphid, Schizaphis graminum and onion thrips, Thrips tabaci on wheat plants during two successive growing seasons 2016 and 2017. The three tested insecticides were lambda- cyhalothrin 5% EC at the rate of 100 ml/100 l , thiamethoxam 25% WG at the rate of 20 g/100 l and malathion 57% EC at the rate of 150 ml/100 l. Twelve treatments (11 insecticides and their mixtures with adjuvants + control) were replicated four times in a completely randomized design. Chemicals were sprayed using a knapsack sprayer motor in separated plots (1/100 faddan). Mean numbers of wheat aphids and onion thrips were recorded before spraying and post treatment periods of 1, 3, 7 and 10 days. Results showed that application of the tested insecticide lambda-cyhalothrin either individually or in combination with sylgard 309 or tween 80 resulted in a significant reduction in the number of the wheat aphid recording 100% mortality in all treatments as initial effect in both seasons 2016 and 2017. Based on general average, a clear effects of lambda-cyhalothrin with sylgard 309, lambda- cyhalothrin with tween 80 and lambda- cyhalothrin were the highly toxic and rapidly kill the tested aphid recording 96.73, 95.83 and 95.43% mortality, respectively, in season 2016 and 98.33, 98.12 and 97.35% mortality, respectively, in season 2017 followed by thiamethoxam and its mixtures then malathion with sylgard 309, malathion with tween 80 and malathion alone recording 86.30, 85.87 and 83.56% mortality, respectively, in season 2016 and 90.77, 90.63 and 88.60% mortality, respectively, in season 2017. After 1 day of spray, lambda-cyhalothrin recorded the most effective treatment resulting in 100% thrips reduction, the same result was recorded for lambda-cyhalothrin + sylgard 309 (100%) and lambda-cyhalothrin + tween 80 (100%). Thiamethoxam, malathion and their mixtures with the two adjuvants caused also 100% thrips reduction. Mortality percentage induced by sylgard 309 and tween 80 were only 56.67 and 49.58%, respectively during season 2016. Similar results were recorded after 24 hr. of application in the second season 2017. After 3, 7 and 10 days of treatments, lambda-cyhalothrin plus sylgard 309, lambda-cyhalothrin + tween 80 and lambda-cyhalothrin alone induced the highest percentages of mortality during seasons 2016 and 2017, respectively, which differed significantly than control. Moreover thiamethoxam with sylgard 309 was recorded 100, 92.77 and 87.40% thrips reduction after 3, 7 and 10 days from spray, respectively, during seasons 2017. However, the results showed also that malathion and its mixtures caused lower percent mortality than the other two tested insecticides and its mixtures during season 2016 and 2017. All the insecticides and their mixtures were significantly better than untreated check in reducing the tested pests population. Lambda- cyhalothrin proved the best effect followed by thiamethoxam and malathion.

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