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

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.

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.

Whiteflies first appeared 13 days after sowing (27^th SMW) and reached a peak of 7.73 per plant (cage) and 3.29 per trifoliate (visual) at 29^th 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 (28^th 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 (32^nd 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, nonsignificant 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.