Weather Associations and Disease Progression of Potato Late Blight under the Influence of Different Sowing Dates at Tarai Region of Uttarakhand
Aditi Maithani *
Department of Plant Pathology, GB Pant University of Agriculture and Technology, Pantnagar (263145), Uttarakhand, India.
Shailbala Sharma
Department of Plant Pathology, GB Pant University of Agriculture and Technology, Pantnagar (263145), Uttarakhand, India.
Ayushi Chamoli
Department of Plant Pathology, GB Pant University of Agriculture and Technology, Pantnagar (263145), Uttarakhand, India.
Tannu Rani
Department of Plant Pathology, GB Pant University of Agriculture and Technology, Pantnagar (263145), Uttarakhand, India.
*Author to whom correspondence should be addressed.
Abstract
Aim: Potato late blight caused by Phytophthora infestans (Mont.) de Bary was analysed to assess the effects of sowing dates and the relationship between disease development and weather parameters in the 2023-24 potato season at the Vegetable Research Centre, G. B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand.
Study Design: Disease severity was assessed across three sowing dates and two varieties, Kufri Bahar (V1) and Kufri Jyoti (V2), in a split-plot experiment with four replications
Place and Duration of Study: Vegetable Research Centre, G. B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, during the 2023-24 potato season.
Methodology: Disease severity was assessed visually using a 0–100% scoring scale (European and Mediterranean Plant Protection Organization,1989) under three sowing dates and two varieties, Kufri Bahar (V1) and Kufri Jyoti (V2), at seven-day intervals across five assessment dates, from 19th December 2023 to 16th January 2024. Weekly mean disease severity was correlated with weekly mean weather parameters (n = 5) during that season, followed by fitting of exponential, monomolecular, logistic and Gompertz growth models.
Results: On 16th January, the mean disease severity was 58.72% for D1, 54.36% for D2 and 46.75% for D3. The mean disease severity of the two varieties was 59.65% for Kufri Bahar and 46.91% for Kufri Jyoti. Among the four disease-progress models, Gompertz had the highest reported R2 values, from 0.9965 to 0.9997, and the lowest Akaike information criterion (AICc) for all six treatment combinations. For the disease-weather relationship, disease severity was negatively correlated with maximum temperature (r = -0.978), sunshine hours (r = -0.968) and evaporation (r = -0.848). Minimum temperature (r = 0.436), morning relative humidity (r = 0.611), afternoon relative humidity (r = 0.906) and wind velocity (r = 0.995) showed positive correlations. These results are from a single season at one location and are descriptive.
Keywords: Phytophthora infestans, late blight, disease severity, sowing date, weather parameters, Pantnagar