Relationship between Whiteflies, Yellow Mosaic Severity, Weather and Crop Age in Soybean

Background: Yellow mosaic disease (YMD), caused by the Mungbean yellow mosaic India virus (MYMIV), seriously affects soybean production in the central and northern regions of India. Methods: The present investigation was conducted to reveal the relation among the fluctuating population of whiteflies, YMD progression, meteorological parameters and crop age in four varieties, i.e. 335, JS 20-34, NRC 86 and MACS 1520, at J.N.K.V.V., Jabalpur, during kharif 2021 (June to September). The whitefly population, by visual and cage and YMD severity were recorded at weekly intervals. Result: Whiteflies first appeared 13 days after sowing (27th SMW) and reached a peak of 7.73 per plant (cage) and 3.29 per trifoliate (visual) at 29th SMW (July, 16-22). During this maximum and minimum temperature, morning and evening RH were 33.4 and 25.4°C, 84.10 and 70.0 %, respectively. Whiteflies on JS 335 (0.639* and 0.635*) and MACS 1520 (0.672* and 0.639*) significantly positively correlated with maximum temperature in visual and cage counts. Wind speed exhibited a significant negative relation with a whitefly count of JS 335 (-0.753*) and MACS 1520 (-0.764*). YMD initiated (28th SMW) at high temperature (max 33.3°C and min 25.1°C), low rainfall (33.2 mm), less humid conditions (evening 58.3-morning 85.1 %) and presence of whitefly. In contrast, at the time of maximum disease progression (32nd SMW), comparative low temperature (max 28.5 and min 24.2°C) and high humid conditions (evening 79.0-morning 90.0) prevailed. Among the four varieties, maximum disease severity was recorded in JS 20-34 (48.16%). The corresponding week’s maximum temp (0.771**) and sunshine hours (0.792**) were negatively significant and evening RH (0.717*) and wind speed (0.708*) had a positively significant relation with mean YMD progression. A similar significant association was also obtained between the previous week¢s parameters and disease. YMD and whitefly exhibited a negative, non-significant association. Crop age also linked non-significantly with YMD progression. The present findings could be utilized to predict vector and YMD and to formulate appropriate management strategies for both.