EFFECT OF ETHYLENE ON ACTIVATION OF LESION DEVELOPMENT FROM QUIESCENTINFECTIONS OF COLLETOTRICHUM-GLOEOSPORIOIDES IN AVOCADO FRUITS

Exposure of Colletotrichum gloeosporioides conidia placed on avocado w ax and on intact avocado to 45 mu l of ethylene per liter stimulated s pore germination, appressorium formation, and proliferation, Exposure of immature cultivar Fuerte avocado fruits inoculated with C. gloeospo rioides to 45 mu l of ethylene per liter enhanced appressorium prolife ration and an early climacteric but did not affect lesion growth durin g 20 days following the treatment, During this period fungitoxic conce ntrations of the antifungal diene in the fruit peel remained at concen trations higher than 2,260 mu g fresh weight. Overmature cv. Reed avoc ado fruits inoculated with C. gloeosporioides and exposed to 45 mu l o f ethylene per liter showed enhanced germination, single and multiple appressorium formation, and earlier fruit ripening, Lesion development by C. gloeosporioides occurred in ethylene-treated fruits in parallel to the development in untreated fruits, Levels of the antifungal dien e from the second day after harvest decreased in parallel in ethylene treated and untreated fruits, We conclude that exposure of avocado fru its to exogenous ethylene treatment induces multiple appressorium form ation and fruit ripening, but it does not activate lesion development by C. gloeosporioides.