Aim: Hopper incidence proliferates on mango foliage, trunk, and panicle during flowering stage and increases the flower drop which reduces yield drastically. Factors affecting the incidence of hoppers on mango cultivars were studied for two consecutive years (2019-2020 and 2020-2021). Study Design: Weather data was collected from the meteorological observatory of the University. The weather parameters were correlated and relationship between the weather parameters were examined by the correlation and stepwise regression analysis were done using Microsoft Excel 2007 software. Methodology: Twelve years old mango cvs. Himsagar, Bombai and Langra planted at 8×8m distance at the Instructional Farm of Dept. of Pomology & Post Harvest Technology, Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar, West Bengal were considered for the experiment. Hopper population was recorded at monthly interval from the mango tree after shoot pruning (30cm from the tip) as well as from another set of plants where no shoot pruning was performed (control treatment) and the relationship between weather parameters and pest dynamics were studied. Results: Highest significant negative correlation was found between hopper incidence with maximum relative humidity (r ꞊ -0.683*) followed by minimum relative humidity (r ꞊ -0.682*) in shoot pruned plants of Himsagar variety and the lowest significant correlation (r ꞊ -0.520*) was found in non-pruned (control) plants of Bombai between hopper population and minimum temperature. It is revealed from the stepwise regression equation that combined effect of all the weather parameters had more influence on the hopper population than the individual weather factor. In case of unpruned plants of Himsagar, Bombai and Langra, the impact of weather factors on hopper population variation could be explained upto 67.8%, 85.8% and 49.3%, respectively. While, in shoot pruned plants it was found as R2 = 0.534 for Himsagar and R2 = 0.383 for both Langra and Bombai. Conclusion: It is stated that environmental factors particularly maximum relative humidity, minimum relative humidity and minimum temperature had significant relationship with the variation of hopper population in different mango varieties after shoot pruning as well as in unpruned plants. The regression model could explain upto 38.3 to 85.8% variation of hopper incidence in different mango varieties.
Parameshwar et al. (Wed,) studied this question.