Vegetos

Abstract

A field study was conducted to evaluate the effect of soil and foliar applied potassium on pest and disease incidence on Bt cotton hybrid MRC-7351 at Main Agricultural Research Station, UAS, Dharwad in Vertisol during 2012–13 and 2013–14. The crop was sown in a randomized complete block design and was replicated thrice. Pooled data of two years indicated that the best results were found when cotton plants were treated with 100: 50: 75 (RDNP+ 150% RDK) + 2% KNO₃ foliar spray at 70, 90 and 110 DAS (T₈) for higher total number of bolls (46.91), highest seed cotton yield (2689 kg ha⁻¹), lower incidence of pests viz., thrips (2.39 and 1.53 per 3 leaves), jassids (1.68 and 1.57 per 3 leaves), aphids (2.31 and 1.44 per 3 leaves) and shoot weevil (4.19 and 2.60 per 10 plants) populations at 70 and 90 DAS, respectively over rest of the treatments. Significantly lower disease incidence viz., grey mildew (Ramularia areola) (13.89 PDI), leaf rust (14.16 PDI), Alternaria leaf blight (8.05 PDI), Cercospora leaf spot (12.78 PDI) and Rhizactonia wilt (0.72 PDI) were also recorded in the treatment receiving 100: 50: 75 (RDNP+ 150% RDK) + 2% KNO₃ foliar spray at 70, 90 and 110 DAS (T₈). Thus, it can be concluded that significant reduction in pests population, disease incidence and higher economic yield can be achieved with higher levels of soil applied potassium fertilizers plus foliar spray of KNO₃ in Vertisol.