Anthracnose development and quality of chitosan-coated sweet pepper (Capsicum annuum L.)

The study was conducted to determine the causal organisms of sweet pepper anthracnose, the factors that favored its development, to assess the response of the pathogen to chitosan and the pathological, physical and physiological characteristics of chitosan - coated and uncoated peppers. The pathogenicity tests confirmed that Colletotrichum phomoides (Sacc.) Chester collected from Laguna and C. capsici (Sydow) Butler and Bisby from Benguet caused anthracnose disease in sweet pepper. High relative humidity levels, moderately high temperature and wide range of pH favored development of anthracnose. C. capsici developed rapidly at a higher temperature range (27 to 35 deg C) and wider pH leveld of 95 to 100% compared with C. phomoides which developed well at 27 to 30 deg C and a relative humidity from 90 to 100%. There was no difference in fungal growth at the different pH levels tested (pH 4 to 9). Chitosan at 1 to 4% effectively controlled the two Colletotrichum spp. It was effective whether applied before or after inoculation with both pathogens. The inhibitory effect of chitosan on the pathogens were not immediate unlike Prochloraz which either pathogen. The inhibitory effect of chitosan on the pathogens was not immediate, unlike Procholaz which completely inhibited spore germination and mycelial growth of both fungi. Chitosan reduced spore germination and inhibited subsequent mycelial growth of the conidia that were able to germinate. Wall thinning and lysis of hyphal branches were observed in chitosan-treated spores. The epidermal and parenchyma cells of chitosan-coated tissues inoculated with either Colletotrichum sp. remained intact. No fungal fruiting bodies were observed in cross-sections of chitosan-treated tissues. This shows the fungistatic property of chitosan which is comparable in action with the Prochloraz fungicide. Chitosan thus coated fruits exhibited delayed ripening, a marked reduction in weight loss, and inhibition of respiration rate and ethylene production. Chitosan reduced anthracnose infection, greatly inhibited the physiological processes of sweet peppers and maintained good over-all appearance of coated fruits.