Control of cotton bollworms with fenvalerate in India

The synthetic pyrethroid fenvalerate (Sumicidin^® 20E¹) has been tested in 64 field trials of the control of bollworms on rainfed and irrigated cotton in Maharashtra, Tamil Nadu, Punjab, Andhra Pradesh, Haryana, Rajasthan, Madhya Pradesh, Gujarat and Karnataka. Fenvalerate, at dose levels of 50–150 g a.i./ha, was tested on 15 varieties of cotton, with long, extra-long, short and medium staples. From two to nine sprays were applied at intervals of 7–30 days, depending on whether the insecticide was sprayed according to a calendar-based schedule or when needed. Fenvalerate was compared with conventional insecticides such as carbaryl, monocrotophos, endosulfan and phosalone, and also with the synthetic pyrethroids permethrin, cypermethrin and deltamethrin. The percentage of bollworm-infested plants in the fenvalerate-treated plots ranged from zero to 21·8% and in the untreated plots was up to 100%. With conventional pesticides the maximum level of infestation was 97·2%. Increases in yield of seed cotton from fenvalerate-treated plots over those from plots treated with conventional pesticides were 54%, 57%, 67%, 84%, and 86% over monocrotophos, carbaryl, quinalphos, phosalone and endosulfan, respectively, representing increases of 791–1046 kg/ha.