Seasonal dynamics of Panonychus ulmi (Koch) (Acari: Tetranychidae) on four varieties of mulberry in Kashmir valley, India

The present study was conducted to measure the population dynamics and seasonal variation of Panonychus ulmi (Koch) on four commercial mulberry varieties viz. Goshoerami, KNG, Tr10 and Ichinose in Kashmir valley. Observations were made fortnightly on the mite density per leaf by selecting five plants from each of four accessions and five branches from each plant with the help of 20x hand lens. Influence of weather parameters on the population build-up and seasonal variations were quantified. The population of P. ulmi was highly affected by weather parameters and was very low during spring and reached maximum in the midst of summer in the varieties selected. Tr10 and Goshoerami varieties were found the most susceptible with the highest population number; however, other varieties showed little resistance. Correlation and multiple regression analysis showed significant relation between P. ulmi population build-up and weather parameters. It can be concluded, that P. ulmi is a serious pest of mulberry plants and can cause significant loss to mulberry foliage. Temperature and relative humidity are the key factors determining rapid multiplication of this mite in mulberry ecosystem.