N Save Nature to Survive 8(2): 493-497, 2013 www.thebioscan.in 493 STUDIES ON MORPHOLOGY OF MANGO ANTHRACNOSE DISEASE CAUSING FUNGUS COLLETOTRICHUM GLOEOSPORIOIDES (PENZ.) PENZ. AND SACC. AND EFFICACY OF AZOXYSTROBIN AGAINST THE FUNGUS UNDER IN VITRO AND IN VIVO CONDITION N. K. ADHIKARY*, S. DEY AND J. TARAFDAR Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Kalyani- 741235, Nadia, West Bengal, India e-mail: nayan.bckv@gmail.com INTRODUCTION Mango ( Mangifera indica L.) is one of the world’s most important and esteemed fruits and described by some as the “king of all fruits”. India is the world’s largest producer (52%) in global mango production. Because of diverse production conditions and the vast area grown, mango suffers from a number of diseases, some of them taking heavy toll on the crop and limiting production and productivity. Among the diseases, mango anthracnose caused by Colletotrichum gloeosporioides is the most serious disease (Ploetz, 1999). Initial infection starts from leaves and spreads to reproductive structure (flower) causing blossom blight, which destroys inflorescence leading to considerable reduction in fruit yield. Much attention and efforts on anthracnose control has concentrated mostly on the use of fungicides. The indiscriminate use of different fungicides causes potential threat to human health, increase in pathogen resistance, mutation and causes environmental hazards. Using of organic sulphur (Dithio-carbamates) fungicides like zineb, maneb and heterocyclic nitrogen compounds like captan gave adequate control against anthracnose. However these fungicides have shown phytotoxic effect to flowers (McMillan, 1972). The fungus developed resistance to benomyl (0.1%), a systemic fungicide used for controlling of anthracnose disease of mango (Akthar et al., 1998; Dodd et al., 1991). Assessment of these reports, focus on the evaluation of new fungicides for controlling mango anthracnose and increasing mango production. Strobilurins are the leading systemic fungicide, developed from naturally occurring antifungal compounds found in wood- decaying mushroom fungus like Oudemansiella mucida and Strobilurus tenacellus. It has broad-spectrum activity against large number of plant diseases such as leaf spot (Cercospora beticola), black spot (Guignardia citricarpa) of citrus, gray mold (Botrytis cinerea) of fruits and vegetables, powdery mildew (Erysiphe betae) of sugar beet, post-harvest rot (Colletotrichum gloeosporioides) of avocado (Slawecki et al., 2002; Anesiadis et al., 2003; Miles et al., 2004) Hence the present study was carried out to evaluate the efficacy of azoxystrobin on mycelial growth and conidial germination of C. gloeosporioides under in vitro condition and in controlling, mango leaf anthracnose disease under in vivo condition. Its effect on the fruit yield was also evaluated. MATERIALS AND METHODS The pathogen C. gloeosporioides was isolated from infected mango leaves. Isolation was made by cutting a small section of anthracnose infected portion along with healthy areas, which was surface sterilized with 1% NaOCl solution (Iqbal et al., 2010), and rinsed in sterilized distilled water. It was then placed into the sterile petri plates containing solidified potato dextrose agar (PDA) medium, and incubated at 28±2ºC. The pure culture was maintained in PDA slants. ABSTRACT Anthracnose disease caused by Colletotrichum gloeosporioides is one of the most serious diseases causing yield losses in mango. For controlling this disease much of attention and efforts has concentrated on the application of fungicides. The indiscriminate use of different fungicides possesses potential threat to human health, phytotoxicity, environmental hazards and development of pathogen resistance. Keeping this in view, the efficacy of azoxystrobin, one of the strobilurin class fungicides, which has broad-spectrum activity against large number of plant diseases, was evaluated both under in vitro and in vivo conditions. In in vitro tests, azoxystrobin significantly reduced both mycelial growth and conidial germination of C. gloeosporioides in PDA media. Although the mycelial growth and conidial germination of the fungus was declined continuously in 100, 200, 300 and 400ppm, the optimum rate was obtained at 100ppm where it responded continuously to climb with increasing rates. In field experiment, azoxystrobin treated trees showed lesser leaf anthracnose than control. The reduction of anthracnose intensity and yield increased curve obtain, shows flattening between the range 100 and 400ppm concentrations, hence the optimum rate of azoxystrobin was fixed to be at 100ppm for the control of anthracnose disease. KEYWORDS Mango Anthracnose Azoxystrobin PDI Mycelial growth Conidial Germination Received on : 23.12.2012 Accepted on : 10.03.2013 *Corresponding author