Bio-efficacy of chemicals on management of mealybugs in marigold (Tagetes spp. L)

Abstract

A field trial was undertaken at the experimental field of Department of Floriculture and Landscaping, College of Agriculture, OUAT to evaluate the efficacy of different chemicals against mealybugs. The crop was raised during rabi, 2015-16 and the experiment was designed in a RBD with nine treatments replicated thrice with normal agronomic practices recommended for the crop. On appearance of the pest different treatments were imposed with a hand compression sprayer using 500 litres of spray solutions per hectare. Observations on the number of mealybugs/plant were recorded one day before (DBS) and at 5, 10 and 15 days after the chemical spray (DAS). The mealybug incidence recorded the lowest with Thiamethoxam 0.5g/ l registering 100.00% reduction over control even after 15 DAS. The combination product Propargite 50%+ Bifenthrin 5%, tolfenpyrad and bifenthrin were the next best effective treatments in reducing the number of mealybugs/ plant (6.33- 8.67). Whereas propargite, dicofol, sulphur and spiromesifen were not effective with 2.25- 12.48 per cent reduction in mealybug population over control at 15 DAS. In the present evaluation Thiamethoxam gave superior control of mealybugs over with the insecticidal effect of Propargite 50%+ Bifenthrin 5%, tolfenpyrad and bifenthrin in controlling mealybugs which is well documented. Therefore, Thiamethoxam 25WG @ 0.5g/ l may be recommended for the best control of mealybugs.