Impact of sowing dates on incidence of major insect pests of castor (Ricinus communis L.) in South-Western Haryana

The influence of different dates of sowing and various weather variables was studied on some major insect pests attacking the economically important castor crop. The susceptible castor hybrid DCH 177 was cultivated on six different dates of sowing at fortnightly interval during May–August, 2018. Crop sown during late May and first fortnight of June (i.e., the “very early sowing” and the “the early sowing”) were found to be least infested by Empoasca flavescens but severely infested with S. litura larvae and the capsule damage by Conogethes punctiferalis was also very high in these two sowing dates as compared to crop sown at other dates. Maximum incidence of E. flavescens and Achaea janata was noticed in late sowings. Correlation analysis revealed that the evening relative humidity influenced the leafhopper nymphal population significantly whereas, the capsule damage by C. punctiferalis was significantly influenced by the minimum temperature and wind velocity. The influence of weather parameters on larval population of A. janata and Spodoptera litura was found statistically non-significant. The study highlights the significance of sowing date in the insect pest management scenario by defining the ultimate degree of infestation levels of insect pests.