International Journal of Environment and Climate Change

An experiment was conducted at Sardarkrushinagar, Gujarat during the rabi seasons of 2022-23 and 2024-25 to study the effect of sowing dates on insect pests and diseases of cumin. The experiment was laid out in randomized block design (RBD) with seven sowing dates: 1^st Nov (D1), 5^th Nov (D2), 10^th Nov (D3), 15^th Nov (D4), 20^th Nov (D5), 25^th Nov (D6) and 30^th Nov (D7) with four replications. The observations of pest and disease were recorded at weekly intervals starting from their appearance. The results revealed that aphids was appeared in the 3^rd standard meteorological week (SMW) and remained active until harvest during both the years. Aphid incidence was lower in early sown crop as compared to later sown crop. Maximum temperature in the range of 25.0 to 30.0 °C was found to be the most influential weather parameter for the initiation and development of aphid. Hence 3^rd order polynomial model fitted with Tmax which caused 70.1% variation in aphid population. The incidence of blight disease was appeared in the 2^nd SMW during 2022-23 and in the 3^rd SMW during 2024-25. Early sown crop suffered with more blight incidence compared to later sown crop during both the years. Temperature and relative humidity had a significant positive impact on disease development. However, minimum temperature and dew were found to be the most influential weather parameters. The multiple linear model developed with Tmin and Dew which explained 93.2% variability in disease intensity.