Solanum muricatum- a new host of Phytophthora infestans

Abstract

Solanum muricatum, known as pepino, is a species of evergreen shrub grown for its sweet edible fruits. It has recently been introduced in Himachal Pradesh from northeastern region. In field surveillance conducted during the months of January and February 2012 and 2013, blight symptoms were noticed on leaves and fruits of pepino. The severity of the disease on leaves ranged between 10 and 15 per cent. The disease first appeared as water-soaked, light brown lesions on the leaf blade. The lesions turned dark brown, dry and brittle at the advanced stage of infection. On fruits, late blight infections produced dark brown firm lesions which got enlarged and destroyed the entire fruit. The associated pathogen was isolated from the diseased leaf tissue on to potato dextrose agar medium. After 5-7 days of incubation at 25 ± 1°C, white fluffy colonies of mycelium appeared and the morphological characters of the fungus were studied. On the basis of morphological characters of the pathogen, it was identified as Phytophthora infestans (Mont) de Bary. Pathogenicity was also proved by artificially inoculating healthy detached pepino leaves. This is the first report of S muricatum as a new host of P infestans in Himachal Pradesh.