Role of weather parameters on potato late blight disease caused by Phytophthora infestans (Mont) de Bary and its chemical management
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Date
2022-06
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Potato (Solanum tuberosum) belonging to the family Solanaceae is one of the important crops in terms of human consumption. Nutritionally, it is second important crop after soybean for protein/ha and is considered a non-fattening, nutritious and wholesome food. It is a crop that can be grown as both rabi as well as kharif season providing more revenue to the farmers. Besides playing a significant role in the cropping system worldwide, potato crop suffers from huge losses due to bio stresses which can be biotic or abiotic. Late blight of potato is one of them and is caused by Phytophthora infestans which appear as water-soaked pale green lesions near the tip and margin of leaves. On the lower side of leaves white fungal growth appears and later infection spread toward the stem and other parts of the plant. Tubers are also infected with late blight pathogen and become firm, dry, brown and prone to rotting by bacteria. A loss of 100% can be seen within a week if the environment is favorable for pathogens. The field experiments were conducted at VRC, Pantnagar during 2021-22 cropping season. The present study focuses on the effect of prevailing environmental conditions on potato crops. The potato crop was sown at three different dates of planting to study late blight severity and its correlation with weather parameters. Similarly, nine potato varieties were screened out not only for late blight resistance but also to study the effect of weather parameters in each potato variety. Field experiment on fungicide scheduling, one resistant (Kufri Khyati) and one susceptible (Kufri Bahar) variety of potato were selected to study the effectiveness of different fungicidal combinations against late blight disease. Further, efficacy of different new fungicides was also tested against late blight of potato and compared to farmer’s practice in terms of cost-benefit ratio. Results obtained from experiments showed that less blight severity was in late sown crop as compared to timely and early sown crop. Correlation analysis revealed that maximum temperature was negative correlated with disease index while, minimum relative humidity was significant and positively correlated. Rainfall was also found to play a significant role in disease progression. In an experiment of screening of nine different potato cultivars, Kufri Chipsona- 3, Kufri Sadabahar and Kufri Surya were found resistant with the minimum effect of weather parameter against late blight disease. In an experiment on fungicide scheduling for late blight disease management, treatment consisting of ametoctradin + dimethomorph @ 0.2% was found effective in both Kufri Bahar and Kufri Khyati. But better results were obtained for potato cultivar Kufri Khyati as it is more resistant to late blight under field conditions. Among all the new tested fungicides, treatment of oxathiapiprolin 10.1% OD @ 200ml/ha was found the most effective followed by amisulbrom 20% SC @ 500ml/ha and picoxystrobin 25% SC @ 500 ml/ha and these treatments gave more cost- benefit ratio as compared to farmer’s conventional practice.