Author(s): Falade MJ

Abstract: The yield and quality of mango production in the tropics have been considerably poor due to the problem caused by Colletotrichum gleosporioides (mango anthracnose). Control of the disease relies on the use of chemical fungicide which has an adverse effect on soil and the environment in addition to the development of resistance by pathogens. Based on this, laboratory studies were conducted to determine the baseline sensitivity of C. gleosporioides to varying levels of copper 1 oxide metalaxyl and ridomil gold. The fungicide was mixed with Standard Dextrose Agar (SDA) at five concentrations (0.6, 1.3, 1.9, 2.6 and 3.3 g/litre). The effect of the mixture was observed on the growth, mycelia inhibition and conidia germination of the fungus in-vitro. Control plates were those without fungicide mixture. Data collected were analyzed and means were separated by the least significant difference. Results from the study showed statistically significant differences (p<0.05) in growth rate, mycelia inhibition and condition of the fungus. Inhibition of growth was directly proportional to the concentrations of the fungicide used in the study. At 3.3 g/litre of the fungicide, complete inhibition (100%) was observed while at 0.6 -2.6 g/litre, inhibition was between 70-77%. Growth of the fungus was faster on SDA attaining 13.4 mm/day when there was no fungicide (control). However, at different concentrations of the fungicide (0.6-3.3) growth of the fungus reduced from 13.4 mm/day to values between 3.1-4.0 mm/day. There was 73-100% inhibition of conidia germination irrespective of the concentrations of the fungicide used in the experiment. The study concluded that C. gleosporioides responds to the varying levels of the fungicide and the optimum value of 3.3 g/litre is the most effective in the management of the disease.

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