ROOT ROT OF CHILLI INCITED BY Sclerotium rolfsii Sacc. AND ITS MANAGEMENT- A REVIEW

Chilli (Capsicum annum L.) belongs to the family solanaceae is mainly cultivated for its vegetable green fruits and dry chilli as the spice. It is believed to be originated from South America. It is a rich source of Vitamin C, A and B. Chilli is valued for pungency which is imparted by an alkaloid, Capsaicin and the red pigments (Capsanthin, Capsorubin and Capxanthin). Chillies are widely used as spice, condiment, culinary, supplement, medicine, vegetable and are ornamental plants too. It is an important food flavouring ingredient for flavouring many vegetarian and non-vegetarian food products. In view of its multifarious uses, the demand for chillies has been on the increase world over. In India it is an important cash crop, which is grown for the domestic market and for export. In India, chillies are grown in almost all states of the country and the major growing states in terms of production are Andhra Pradesh, Karnataka, Orissa, Maharashtra, West Bengal, Rajasthan and Tamil Nadu. There are several varieties of chilli cultivated in India. The most popular among these are, Sannam, LC334, Byadagi, Wonderhot, Jwala etc. The crop suffers from many diseases like damping off, anthracnose or fruit rot or dieback, wilt, leaf spots and powdery mildew. Among the fungal diseases, root rot of chilli caused by Sclerotium rolfsii has attained the economic importance. In recent years, this disease is causing the economic losses in chillies crop (Kalmesh and Gurjar 2001). The disease In India the root rot caused by this pathogen was first time reported by Shaw and Ajrekar (1915) who had isolated the pathogen from rotting potatoes which they identified as Rhizoctonia destruens Tassi. Later studies convinced Ajrekar that the fungus involved in rotting of potato was Sclerotium rolfsii but not R. destruens (Ramakrishna, 1930). During 1985, the color rot to chilli caused by Sclerotium rolfsii was observed in Maharashtra at Vidarbha region (Wangihar, 1985). Sclerotium rolfsii Sacc. is a well known polyphagous, ubiquitous, omnivorous and most destructive soil borne fungus. This was first time reported by Rolfs (1892) as a cause of tomato blight in florida. Later, Saccardo (1911) named the fungus as S. rolfsii sp. But, in India, Shaw and Ajrekar (1915) isolated the fungus from rotted potatoes and identified as Rhizoctonia destruens Tassi. However, later studies showed that, the fungus involved was S. rolfsii (Ramakrishnan, 1930). Mundkar (1934) successfully isolated the perfect stage of S. rolfsii. Kulkarni et al. (1994) while studying the most susceptible growth stage of groundnut to S. rolfsii maximum infection, colonization, disease development and mortality was recorded in 15 days old plants and least, mortality in 105 days old plants. Morphology of the Pathogen Narsimha rao (2000), reported that, fungus Sclerotium rolfsii showed characteristics with white, radiating abundant mycelial growth on the affected portion of potato plant and tuber. Large number of sclerotial initial were noticed on the mycelial mat. Initially sclerotia exhibited white colour later turn to chocolate brown. Sclerotia were superficial on the affected part, spherical or ellipsoidal and measured 0.5 mm to 2.5 mm in diameter. Non-germianted sclerotia become soft and broke easily. Maceration of cortical cells was common. A bacterial like organism was consistently associated with the ruptured and macerated scleortia.