Curvularia leaf spot of pointed gourd in India

Pointed gourd' or parwal' (Trichosanthes dioica) is a member of the cucurbit family and an important vegetable crop in India which is also widely grown in West Bengal. Fungal diseases are a major constraint to cultivation of pointed gourd. Yellow to dark brown spots were observed on leaves of pointed gourd in different fields in West Bengal during June-August 2015. In extreme cases, plants showed necrosis during early stages of growth and did not bear any fruit. Symptomatic leaves were collected for fungal isolation and colonies that produced an olive-grey mycelial mat on potato dextrose agar were obtained. Ascendant or erect conidiophores with dark brown pigmentation and light brown, oblong to cylindrical conidia with 2-3 transverse septa were visible using a light microscope. The fungus was identified as Curvularia spicifera (anamorph: Bipolaris spicifera) on the basis of morphological characteristics. Pathogenicity tests on detached leaves and whole plants confirmed that the isolates were pathogenic. The ITS and 28S rRNA large subunit regions of ribosomal DNA were amplified with two different primer sets for molecular identification of the fungus. The amplicons were cloned and the sequences submitted to GenBank (accession nos. KX910098 and KY411823). Sequence similarities confirmed the organism as C. spicifera. This is the first report of C. spicifera as a pathogen of pointed gourd.