author(s)
SV Hugar, KP Gundannavar and SS Udikeri

abstract
Field experiments were conducted at Agricultural Research Station, Dharwad Farm, Dharwad, Karnataka during Kharif, 2016 and 2017 on the evaluation of a combi product Diafenthiuron 30% + Pyriproxyfen 8% SE efficacy against whiteflies on cotton. The pooled data of two seasons as impact of three sprays revealed 89.00 per cent reduction in Diafenthiuron 30%+Pyriproxyfen 8% SE @ 1200ml/ha treatment followed by at 1000 ml/ha (85.20%), 800ml/ha (73.03%), Pyriproxifen 10% EC @ 100 ml/ha (65.75), Diafenthiuron 50 WP @ 600g/ha (63.09). The reduction was least with Diafenthiuron 30%+Pyriproxyfen 8% SE @ 600ml/ha (56.69). Similarly per cent reduction of white fly nymphs was observed with 81.30, 78.15, 65.32, 58.42, 55.67 and 54.02%, respectively. Per cent increase in yield over check (no protection) was also highest in Diafenthiuron 30% + Pyriproxyfen 8% SE @1200ml/ha (41.42%) followed by at 1000ml/ha (40.43%) and at 800ml/ha (28.98%), but net incremental cost benefit ratio was highest in Diafenthiuron 30% + Pyriproxyfen 8% SE at 1000ml/ha (1:2.03) followed by at 1200ml/ha (1:1.64) and at 800ml/ha (1:1.33). Hence, Diafenthiuron 30%+Pyriproxyfen 8% SE at 1000ml/ha could be used for the management of whiteflies without any phytotoxic effect on plants There was no significant difference between the untreated check and the test chemicals on the grubs and adults of coccinellids (2.15 to 2.80 per plant), number of chrysoperla (2.45 to 2.87 per plant) and per cent parasitization of whitefly nymphs by Encarsia spp. (21.60% to 23.08%). Under changing incidence pattern of insect pests, whitefly management with Diafenthiuron 30% + Pyriproxyfen 8% SE chemical would be quite ideal without compromise on natural control.