Colletotrichum gloeosporioides causing leaf spot disease on Ixora coccinea in West Bengal

Abstract

Occurrence of leaf spot disease of Ixora coccinea (family - Rubiaceae) is first time observed during mid August to October, 2017, from nursery garden of Birbhum district, West Bengal, India. Typical small to large sized light grey spots surrounded by irregular dark brown zonate margin with numerous production of concentric brown to black dot like structures are observed on the upper surface of leaves. Based on cultural, morphological, vegetative and reproductive structures, the causal pathogen of disease is identified as Colletotrichum gloeosporioides which is being considered as new record from West Bengal. Spores of Colletotrichum gloeosporioides produced on host are hyaline, 1-celled, smooth walled, eguttulate, cylindrical with rounded ends measuring 11.2 – 12.8 (av. 12.0) x 3.1 – 5.3 (av. 4.2) μ. Acervuli are pale brown to black, 130.1 – 161.5 (av.147.7) μ in size with numerous, black to dark brown, 1 – 3 septate, unbranched, 36.6 – 59.1 (av. 50.6) x 2.8 – 4.4 (av. 3.7) μ sized pointed setae.