Effect of stage of mechanical inoculation on leaf crinkle disease development in urdbean (Vigna mungo L.) under controlled conditions

Vigna mungo (L.) Hepper, (chromosome no. 2n=24) commonly known as urdbean or blackgram, is a leguminous crop and belongs to family Fabaceae. Urdbean contribute about 11% of total pulse production in India. It is severely affected by various biotic and abiotic factors. Among biotic factors, urdbean leaf crinkle disease is major production constraint. The disease is characterized by crinkled and leathery leaves and floral malformation of plants. In case of severe infection, it caused yield loss up to 62 to 100%. Plant stage at time of infection is important factor, which determine severity of disease and yield loss. In present study, mechanical inoculation was done at different growth stage of urdbean plant. Lower disease incidence with reduced severity was observed for inoculation at later stage. Interestingly, 100% disease incidence with very high severity was observed when inoculation was done in germinated seed however; disease incidence was reduced to 28% in plants inoculated at first trifoliate stage at 50 days after inoculation. The outcome of this study would help in better understanding the host-pathogen interaction.