Vol. 12, Special Issue 12 (2023)

Author(s):
Manjunath H, Govindappa MR, Aswathanarayana DS, Palaiah P and JM Nidagundi

Abstract:
Cotton (sp.), universally known as White Gold, is an economically important cash crop of India. It is the most essential natural fiber crop in the world for textile produce. The necrosis disease of cotton caused by Tobacco streak virus (TSV) was frequently recorded in all cotton growing regions of India. The survey findings indicated the presence of cotton necrosis disease across all regions where cotton was cultivated, with the average incidence varying from 16.70 to 38.76 percent. An investigation conducted to determine the influence of various weather factors, including maximum and minimum temperatures, rainfall, morning and evening relative humidity, sunshine hours and the population of thrips, on incidence of necrosis disease in the susceptible cotton cultivar RCH 659. The first onset of symptom was noticed during 29^th standard meteorological week (SMW) (15 July-22 July) with the disease incidence of 3.00. percent. Over a period of time, disease incidence increased and reached peak of 49.00 percent on 38^th SMW which coincided with the congenial weather conditions. Thereafter the disease incidence gradually decreased to a minimum of 12.00 percent during 49^th SMW (03 December to 09 December). It became evident that, the progression of the disease was closely linked to the prevailing environmental conditions and the population of thrips. In essence, the weather conditions experienced from August to September were found to be particularly conducive to both thrips movement and disease development.