ABSTRACT

Blackgram (Vigna mungo (L.) Hepper) is one of India's most important legume crops, cultivated during both Kharif and summer seasons. In recent decades, the average production of blackgram has drastically declined due to fluctuations in biotic and abiotic factors. Among the biotic factors, insect pests have a detrimental effect on the yield of blackgram. Yellow Mosaic Disease (YMD), caused by Mungbean Yellow Mosaic Virus (MYMV), is one of the major biotic constraints to successful production of blackgram. The disease is transmitted by the hemipteran whitefly, Bemisia tabaci, in circulative and persistent manner.
The whitefly population was highest during the 41st and 42nd Standard Meteorological Weeks (SMWs), with mean values of 69.3 and 64.9, respectively. The whitefly population buildup showed significant positive correlation with maximum temperature and negative correlation with rainfall. Among 119 germplasm lines screened for YMD under field condition, two blackgram germplasm lines i.e., IC 584696 and IC 614830 were found to be moderately resistant, while nine lines i.e., IC 330904, IC 296079, IC 324139, IC 305227, IC 570274, IC 587040, IC 600673, IC 611676 and DBGV-36, were identified as moderately susceptible.
Among all the treatments, seed treatment with imidacloprid 600 FS @ 5 ml/kg seed + foliar spray of (pyriproxifen 5% + difenthuron 25% SE) @ 2 ml/l was found to be more efficient in managing both whitefly population as well as yellow mosaic disease, followed by seed treatment with imidacloprid 600 FS @ 5 ml/kg seed + foliar spray of imidacloprid 30.5% SC @ 0.3 ml/l. The results of the current study, based on similarities in coat protein sequence at both the nucleotide and amino acid levels, as well as phylogenetic analysis, confirmed the prevalence of MYMV strain rather than MYMIV, HgYMV and DoYMV in blackgram in northern parts of Karnataka.