Chemical control of Alternaria and Corynespora leaf spot complex in Bt cotton

Abstract

Cotton is an important cash crop of India as well as Gujarat, enjoying the pre-eminent status as 'White gold' and 'King of Fibres'. Cotton is widely affected by many diseases including Alternaria leaf spot and target spot or Corynespora leaf spot caused by Alternaria alternata and Corynespora cassiicola, respectively. The main objective of the study was to investigate the effectiveness of fungicides against leaf spot complex (Alternaria leaf spot and target spot) of Bt cotton. The field experiment was conducted during Kharif 2022 at Plant Pathological Research Farm, Department of Plant Pathology, BA College of Agriculture, Anand Agricultural University Anand, Gujarat. Fungicides were applied two times at 15 days interval after initiation of disease and results showed that among the tested treatments including control, Azoxystrobin 18.2% + Difenoconazole 11.4% SC recorded significantly lowest disease intensity (18.50% and 17.92%) as compared to control (50.75% and 46.85%), with highest disease control (63.54% and 61.73%) for Alternaria leaf spot and target spot respectively. The highest yield (1968 kg ha ) and ICBR (1:10.62) was -1 recorded in Azoxystrobin 18.2% + Difenoconazole 11.4% SC. The next best treatment found in terms of disease control was Tebuconazole 50% + Trifloxystrobin 25% WG. So in nutshell it was found that readymix fungicides were found best and also cost effective in managing both the diseases.. KEYWORDS :Alternaria alternata, Corynespora cassiicola, leaf spot, fungicides