Studies on mango diseases under tarai region of Uttarakhand
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Date
2014-07
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
India is the largest producer of mango (Mangifera indica L.) both in terms of area and production. In India, Uttarakhand cover about 2.87 % of area under mango cultivation. Mango suffers from several diseases at all stages of its life. These diseases reduce the fruit quality and cause severe losses. Orchard surveys were made on the status of major diseases in the mango growing districts of Udham Singh Nagar. Powdery mildew, malformation, anthracnose and bacterial black spot are important diseases and widely distributed in most of the mango growing areas of Udham Singh Nagar. All the diseases which inflict heavy losses in the orchards (8- 75%). Accurate measurements of mango diseases are important in our study relating disease severity to disease losses and subsequent management tactics. This thesis provides 5 keys for the assessment of important mango diseases. All of which have been prepared from the disease (symptom) appearance to development on different part of the mango trees. Twenty mango cultivars were investigated during 2013 and 2014 for their susceptibility level to PM, MM, BBS, MA in HRC, Pattarchatta of Udham Singh Nagar. These diseases are being managed through fungicides, but the efficiency of control measures depends upon the interaction between pathogen and host, which is influenced by environmental factors. Development of powdery mildew is favoured by Tmax range of 17-310C, Tmin of 11-140C, RH >60% and dry weather especially during February- March. For Anthracnose of Tmax upto 300C and Tmin of 16-200C and RH>70% with intermittent rains proved most effective for disease development. Rasgulla and Redtotapari were resulted in minimum logarithmic infection rate (0.038 and 0.048 per unit per day) and AUDPC (37.41 and 35.05) and also screened out to be resistant against Anthracnose of mango. Similarly, for floral malformation, a T range of 18-260C with high RH was considered optimal for its progress. Bacterial black spot is favoured by a T range of 24-300C with high RH. A reduced period of sunshine with rainfall upto120 mm during fruit development favours the bacterial black spot. Minimum r and AUDPC was found in only one cultivar ‘Chausa’ against floral malformation (0.026 per unit per day and 39.39) and bacterial black spot (0.032 per unit per day and 34.92) in the both respective years. The coefficient of multiple determinations R2 value of twenty cultivars showed that variation of disease incidence in the development of disease explained upto 94% (maximum) in powdery mildew, 98% (max) in Anthracnose, 99% (max) in floral malformation as well as 95% (maximum) in bacterial black spot with combined effect of the weather variables. A regression equation of twenty cultivars were also derived which will be useful in the prediction of above four important disease of mango in Uttarakhand. Our results indicates that data needs to be generated for a longer period and the model be tested at multilocations.
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