2024, Vol. 7, Special Issue 9

Peanut bud necrosis virus (PBNV = Groundnut bud necrosis virus - GBNV) and Tobacco streak virus (TSV) are causing similar necrosis symptoms on Blackgram and greengram resulting in confusion of disease diagnosis at field level and it is necessary to differentiate the diseases as the viruses are transmitted by different thrip species with varying patterns where management practices also differ. Hence, the present study has been taken up for symptomatology of the necrosis causing viruses under field and glasshouse conditions and particle morphology. Field collected symptomatic samples tested by DAC-ELISA with respective antisera. Under field conditions, necrosis/leaf curl disease in blackgram and greengram was manifested with similar symptoms such as veinal chlorosis associated leaf curl. These veins later turned to necrotic resulting in downward curling of leaves where necrotic veins were clearly observed on the under surface of the leaf, occasionally, chlorotic spots turning to necrotic, leaf necrosis leading to death of growing bud. Early infection caused death of the plant. Most of the TSV positive plants were completely necrotic leading to death revealing the rapid necrosis than PBNV. Under glasshouse conditions upon mechanical inoculation, PBNV isolates produced chlorotic, necrotic lesions, chlorotic, necrotic spots, veinal necrosis, leaf necrosis and leaf curl in blackgram; and chlorotic, necrotic rings, chlorotic, necrotic lesions; concentric chlorotic and necrotic rings; veinal necrosis, smalling of leaves, stunting, mosaic mottling and apical necrosis were observed with TSV inoculations, whereas greengram genotypes showed chlorotic and necrotic lesions, leaf chlorosis, necrosis, veinal chlorosis, necrosis, chlorotic spots and leaf curl with PBNV infection while TSV showed concentric chlorotic, necrotic rings; veinal, stem and apical necrosis; chlorotic and necrotic lesions. Particle morphology studies revealed quasi spherical virus particles measuring 80-110 nm and 25-30 nm diameter, in the leaf dip preparations of PBNV and TSV isolates of blackgram and greengram by electron microscopy, respectively.