Progressive Horticulture, Vol. 45, No. 2, September 2013 © Copyright by ISHRD, Printed in

[Report] Colletotrichum leaf spot of holy ( tenuiflorum L.)- A new report from Kerala

Malini Nilamudeen*, V.K. Girija1 and C. Nandakumar Department of Entomology, 1Department of Pathology College of Agriculture, Vellayani, Thiruvananthapuram 695522, Kerala, India. *Email: [email protected]

Abstract Commercial cultivation of tulsi demands the development of improved crop husbandry practices. In agro ecosystems, when the area under a crop increases, the potential for pest problems also increases. Hence it goes without saying that the pest problems have to be identified and contained to obtain good quality produce.A fungal leaf spot caused by Colletotrichum gloeosporioides Penz. was recorded for the first time.

Key words: Leaf spot, Colletotrichum gleosporioides, holy basil

India is one of the richest repositories of medicinal earlier in the field. and aromatic in the world. Kerala is one of the In culture plates fungal colonies produced white most advanced states with respect to the use of me- mycelium within four days after inoculation, which later dicinal plants, especially in . Tulsi, meaning turned light pink due to the production of pinkish spore ‘the incomparable one’ is an important medicinal plant mass. The conidia were straight and bullet shaped with which is in demand. The medicinal properties of tulsi an oil globule at the centre, which measured 3x1.5 mm. were known since antiquity. This is mentioned in Based on the cultural and microscopic characters, the Charaka Samhita and Rig Veda. It is used for the treat- pathogen was identified as Colletotrichum gloeosporioides ment of problems related to heart, blood, intestine and Penz. snake bite. , the important chemical constituent of tulsi is useful for the synthesis of vanillin. In Kerala, tulsi has been an ubiquitous member of the homestead farming system. Tulsi leaves were observed with circular, white coloured spots, which later coalesced and resulted in ne- crosis of leaves causing severe reduction in yield (Fig.1 and Fig.2). Leaves showing symptoms of leaf spot were collected from the field. The affected parts were cut into bits and surface sterilized with 0.10 per cent mercuric chloride. The surface sterilized parts were then washed twice with sterile water and were placed on Potato Dex- trose Agar medium (PDA) for initiating fungal growth. Pathogenicity and confirmation of disease were tested by inoculating mycelia on fresh healthy leaves. Three days after inoculation on healthy leaves, lesions devel- oped which were identical to the symptoms observed Fig. 1: Initial symptoms of leaf spot

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The leaf spot caused by C. gloeosporioides was the first report of a fungal disease of tulsi from Kerala. The leaf blight of O. by Colletotrichum capsici V. was reported from India by Alam and Janardhanan (1994). C. gloeosporioides is a common organism causing leaf spot disease (anthracnose) in a wide array of fruit trees, and medicinal plants in Kerala. This has to be taken note of in the context of cultivating tulsi in farming systems with susceptible crops.

Reference Alam, M. and Janardhanan, K.K. 1994. A new leaf blight of French basil caused by C.capsici in India. J Mycol Pl Pathol,10(2): 99. Fig.2: Leaf necrosis during later stages

Received on 11 December, 2012 and accepted on 03 June, 2013