author(s)
Aishwarya P, G Karthikeyan, N Balakrishnan, JS Kennedy and D Rajabaskar

abstract
Watermelon bud necrosis virus (Buniyaviridae; Tospovirus) is the major production constrains in watermelon and it is transmitted by Thrips palmi Karny. A study was conducted during summer 2019 in Tamil Nadu, India to understand the influence of weather parameters (temperature, RH and rainfall) on the vector population and the disease incidence. The result showed thrips population ranged from 0.5 to 18.1/plant and WBNV incidence ranged from 0 to 60 per cent. The thrips incidence started at 10 DAS and reached maximum on 30 DAS likewise the symptomatic expression of disease incidence started at 15 DAS and attained maximum at 70 DAS. The maximum incidence of thrips population was correlated with the temperature of 35.6^oC and 58% of RH. The maximum incidence of WBNV was correlated with the temperature of 35.7 C and 65% RH. Temperature was positively correlated with WBNV incidence (r = 0.7) and thrips population/plant. Relative humidity (r=-0.5) and rainfall (r=-0.5) were negatively correlated with the incidences of thrips population and positively correlated with WBNV incidence (r=0.34 and 0.41) in watermelon.