Vol. 11, Special Issue 11 (2022)

Author(s):
Nayan K Barad, Piyush H Patel and Shivam V Sapteshwariya

Abstract:
Field experiment was conducted to study the impact of fertilizers and irrigation on incidence of aphid and whitefly in Bt cotton at Instructional Farm, College of Agriculture, Junagadh Agricultural University, Junagadh during Kharif, 2018. In case of nitrogenous fertilizer, lowest aphid index and whitefly population was recorded in nitrogen level N₁ (180 kg /ha). Whereas, in case of phosphorus fertilizer, lowest aphid index and whitefly population was recorded in phosphorus level P₃ (75 kg P₂0₅ /ha). Moreover, Lowest mean aphid index and mean whitefly population was recorded in the treatment combination of N₁P₃ [180 kg N/ha + 75 kg P₂O₅/ha] and N₁P₂ [180 kg N/ha + 50 kg P₂O₅/ha], respectively. In case of irrigation intervals and methods, for aphid population, I₃ (21 days irrigation interval) and M₂ (Ridge and Furrow) registered significantly lowest aphid index. While, best treatment combination was I₁M₂­ [7 days interval + Ridge and Furrow] that found lowest aphid population. For whitefly, I₃ (21 days irrigation interval) and M₂ (Ridge and furrow) recorded lowest whitefly population. Moreover, best treatment combination was I₃M₂ (21 days + Ridge and furrow) and found lowest whitefly population. The highest cotton yield found in plots of N₃P₂ [300 kg N/ha + 50 kg P₂O₅/ha]. The aphid and whitefly incidence declined with decreased nitrogenous fertilizer level as well as increased phosphorus fertilizer level.