Author(s):

Rajib kumar Borah and Pranamika Sharma

Abstract: Aquilaria malaccensis Lamk. is one of the most economically important, medicinal and aromatic tree species of North-East India. It is naturally grown and commercially cultivated in different districts of Assam. Locally known as Xanchi or Agar, the Upper Assam region is known for the natural belt of agarwood formation. The principal use of agarwood is in perfume industries. Besides, the essential oil from agarwood is valued for preparation of several pharmaceutical and cosmetic products and its cost is extremely high depending on the oleoresin content of the wood. Due to high demand for agarwood, people are getting engaged in large scale cultivation of this species in this region. But, due to unscientific cultivation practices, new diseases are emerging in the nursery. Unknown fungal infection of A. malaccensis with grey to brown spots on leaves leading to sudden wilting and mortality was observed in seedlings raised in polybags at Rain Forest Research Institute (RFRI), Jorhat, Assam in 2017. The fungal infection causes 89.71% damage to the seedlings at 45 days after transplanting. The pathogen was primarily identified as Rhizoctonia solani ITCC No. 10.693.17 on the basis of morphology. Aqueous suspension of whitish brown growth of the fungus sprayed on leaves produced typical symptoms in about 15 days followed by wilting and death of Aquilaria seedlings. The fungus was highly pathogenic on artificial inoculation. This is the first report of R. solani affecting seedlings of A. malaccensis. Soil drenching and foliar spray of 0.1% Bavistin was found effective in checking further spread of the disease.

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