Viral diseases: a threat for tomato cultivation in Indo-Gangetic eastern plains of India

Abstract

Tomato, worldwide, is infected by several viral diseases which cause stunting, leaf curl, yellowing, mosaic, mottling, necrosis and shoe-string symptoms on plants, leaves or fruits. Among them, bud necrosis disease caused by an orthotospovirus is emerging as a major constraint to the cultivation of tomato for resource-poor farmers. In the Indo-Gangetic eastern plains, bud necrosis disease incidence on tomato ranged from 0 to 45% under field conditions during 2015 and 2016, along with other diseases such as leaf curl and mosaic caused by begomoviruses (0–35%) and tobamoviruses (0–18%) respectively. Thirty four viral infected samples collected from 11 different villages were screened for different viruses using serological and PCR-based methods. The result revealed that most samples were positive for RNA (peanut bud necrosis virus, tomato mosaic virus) and DNA (tomato leaf curl New Delhi virus, tomato leaf curl Gujarat virus, tomato leaf curl Palampur virus, tomato leaf curl Bangalore virus, tomato leaf curl Karnataka virus) viruses along with their satellites (DNA-α and DNA-β) respectively. Further, the incidence of bud necrosis correlates to the weather parameters, which demonstrate that a long dry spell leads to higher incidence of viral disease, whereas lower incidence was observed during the rainy period considering a reduced vector population.