Morphological and molecular identification of Phomopsis azadirachtae causing die-back of neem from different regions of Tamil Nadu, India

Abstract:

Die-back of neem is currently the most serious disease of neem causing considerable damage to the neem trees across India. A fungus Phomopsis azadirachtae Sateesh, Bhat and Devaki is the pathogen that causes die-back of neem. At present the disease can be seen in every neem grown areas of India. Die-back diseased neem twigs were collected from different geographical areas of Tamil Nadu. These twigs were used for isolation of the pathogen and its identification was done by observing colony characteristics and spores. Then for precise identification of the fungus PCR amplification with species-specific primers was employed. Fifteen fungal isolates that exhibited significant variations in the colony colour, radial growth and margin, mycelial type, texture were obtained from the sampled twigs. They were identified via morphological characteristics as Phomopsis sp. and via molecular identification (PCR) they were confirmed to be Phomopsis azadirachtae.