Effect of fruit and leaf exudates for the development of anthracnose and rust pathogens in uguressa

Abstract

Anthracnose and rust are widely spread diseases in leaves, ripening and ripe fruits of uguressa ( Flacourta indica (Burmm.F). Merr) in Sri Lanka. An investigation carried out to determine the effect of fruit and leaf exudates for the development of anthracnose and rust pathogens in fruits and leaves of uguressa. The casual agent of anthracnose ( Colletotrichum gloeosporioides ) and rust ( Uromyces species) diseases were isolated and identified using morphological features of culture media, microscopic observations and Koch’s postulation. Exudates obtained from fruits of all maturity stages and leaves were separated into two fractions that are soluble in ether and water to investigate the effect fruit and leaf exudates for the differentiation of spores of both fungi. Conidia of C. gloeosporioides germinated and produced appressoria within 22 hours on fruit exudates of all maturity stages of uguressa fruits. The highest stimulation of conidia differentiation of C. gloeosporioides was observed in fruit exudates of ripe fruits which are highly susceptible for the anthracnose disease. Chemical substances found in both water soluble and ether soluble fractions enhanced conidia differentiation of C. gloeosporioides . Significantly highest lesion development of anthracnose found on ripe fruits compared to mature and immature fruits. Higher conidia differentiation of C. gloeosporioides was observed in original exudates of leaves compared to ether and water fractions. There was no effect of leaves and fruit exudates for germination on urediospores of Uromyces species. The study revealed uguressa fruits and leaf exudates have chemical substances to stimulate differentiation of spores of C. gloeosporioides and lesion development while there is no any chemical substances that stimulate the differentiation of Uromyces sp. Key words: Anthracnose; Colletotrichum gloeosporioides Exudates; Flacourta indica ; Rust; Uromyces species DOI: http://dx.doi.org/10.4038/jas.v6i2.3862 The Journal of Agricultural Sciences , 2011, vol .6, no 2, pp77-83