Indian Phytopathology 69 (4s) : 643-645 (2016) 643 Indian Phytopath. 69 (4s) : 643-645 (2016) RESEARCH ARTICLE *Corresponding author: suresh41240@gmail.com Aloe vera (Aloe barbadensis mill.) belongs to family Liliaceae, is a perennial, drought resistant succulent plant of South African origin which is distributed to other tropical countries like South Arab, India, East Asia and South East Asia (Rukhsana et al., 2010). The most popular is Aloe barbadensis which has more therapeutic value and referred to as ‘True Aloe’ (Shukla, 2008). In India it is grown in Maharashtra, Tamil Nadu, Andhra Pradesh, Gujarat and Rajasthan. It is a perennial herb with fleshy leaves, often used in various proprietary herbal medicines and in digestive problems as laxatives. The presence of alocetin B helps in stimulation of immune system of the body. The extract of the plant has strong antibacterial activity. In addition to various medicinal uses related to digestives system, now a day, it is also being used in many cosmetic preparations used for skin care (Pandey, 2008). A leaf spot caused by Alternaria alternata (Fr.) Keissler was reported from India (Kamalakannan, 2008). In India, leaf spot is one of the most serious fungal diseases affecting the commercial cultivation of Aloe vera in North India. Among the fungal diseases, leaf spot of Aloe vera caused by A. alternata is one of the most wide spread and destructive disease of Aloe vera under field conditions. It is only recently the crop has gained attention of plant pathologist as a result some important diseases like leaf spot incited by A. alternata causing economic loss to the crop have been reported from different parts of the country. MATERIALS AND METHODS Collection of isolates The isolates of A. alternata were isolated from affected leaf of Aloe vera plants collected from the fields of Medicinal Research and Development Centre, (MRDC), G.B. Pant University of Agriculture and Technology, Pantnagar. Single spore isolation technique was used for obtaining pure culture of the fungus and the subcultures were maintained through hyphal tip method on PDA plates for further use. In vitro, the different fungicides against A. alternata were studied by poisoned food technique (Sharvelle, 1960). The fungicides viz., Chlorothalonil, Carbendazim, Propioconazole, Hexaconazole and Tebuconazole were evaluated against the test fungus at the concentrations of 5, 20, 50 and 100 ppm. Bioagents Trichoderma harzianum, five strains Th-2, Th-4, Th-6, Th-9 and Th-12 were used in the experiments. These strains were obtained from Biocontrol Laboratory, Department of Plant Pathology, G.B. Pant University of Agriculture and Technology, Pantnagar. Pathogenicity test Pathogenicity test was conducted on Aloe vera leaves by inoculation and germination technique in Petri plates. One each leaf placed in 30 Petri plates, inoculated with spore suspension of A. alternata and moist chamber is prepared using sterilized filter paper, Plates were incubated at 26 ± 1°C. The symptoms appeared after 12 days of inoculation. The A. alternata was reisolated Antifungal Efficacy of Fungicides and Bio-control agents against Leaf Spot of Aloevera Incited by Alternaria alternata (FR.) Keissler in vitro SURESH KUMAR VERMA 1 , P. KUMAR 1 , ARJUN LAL YADAV 2 , RATAN LAL SHARMA 2 AND K.K. SAINI 2 1 Govind Ballabh Pant University of Agriculture & Technology, Pantnagar, Uttarakhand. 2 Department of Plant Pathology, Sri Karan Narendra Agriculture University, Jobner, Rajasthan ABSTRACT: Leaf spot disease caused by Alternaria alternata is one of the major diseases of Aloe vera and is prevalent in almost all the Aloe vera growing countries. The present study was carried out to test efficacy of antagonist and fungicides in inhibiting the pathogen under in vitro condition. Among the five strains of Trichoderma harzianum viz. Th-2, Th-4, Th-6, Th-9 and Th-12 tested. Maximum per cent inhibition in mycelial growth was recorded in Th-12 (30%) followed by Th-2 (25) while minimum inhibition (16.25) was observed Th-9. Out of five fungicides tested in vitro, Hexaconazole and Carbendazim was found to be highly effective showing complete inhibition at 100 ppm. Whereas, minimum inhibition (7.50) was recorded in Propiconazole. Key words: Aloe vera, Alternaria alternata, bio-control, fungicides, leaf spot,