Resumo de Damage Quantification And Postharvest Control Of Brown Rot And Soft Rot In Peaches

The purposes of this study were to quantify and characterizepostharvest damages in peaches commercialized at the Companhia deEntrepostos e Armazéns Gerais de Sao Paulo ? CEAGESP, Brazil, as wellas to evaluate the effectiveness of sanitizing products in controllingbrown rot (Monilinia fructicola) and soft rot (Rhizopusspp.). Twenty weekly evaluations were carried out in 2003 and 2004 and1% of all peach boxes from five concessionaires was sampled. Sampleswere stratified according to cultivar, caliber and grower. Every fruitin each sample was assessed as to abiotic damages and pre andpostharvest diseases. The pathogens Monilinia fructicola and Rhizopusspp. were grown in culture medium to enable the conduction of the invitro and in vivo experiments with benzalkonium chloride, chlorinedioxide, Ecolife40® and calcium hypochlorite used curativelyand preventively, and ozone gas used only curatively. Averageincidences of damaged fruits were 42% and 32% in 2003 and 2004,respectively, involving 18% and 12% pre harvest mechanical injuries,12% and 13% postharvest injuries, 3% and 1% pre harvest diseases and 4%and 2% postharvest diseases, in 2003 and 2004, respectively. The fungusCladosporium sp. was the most prevalent pathogen (30% in 2003and 28% in 2004) in the periods evaluated. Postharvest mechanicalinjuries were the most common damages in peaches. Peaches cv. Aurorawere the most susceptible to postharvest diseases. Benzalkoniumchloride and Ecolife40®, both at 1000 ppm, completely inhibited the growth of M. fructicola in in vitro experiments. None of the products tested in this study was effective in the in vitro control of Rhizopus spp. Only the in vivo preventive treatment with benzalkonium chloride at 2 mL. L-1 and Ecolife40® at 3 mL. L-1promoted significant reduction in brown rot in non-injured peaches whencompared to control fruits. The curative use of benzalkonium chlorideat all concentrations tested inhibited the infection by Monilinia fructicola in non-injured peaches. The curative application of calcium hypochlorite at 0,1; 0,2 and 0,3 g. L-1 and chlorine dioxide at 2,0 and 3,0 mL. L-1 also inhibited the growth of Monilinia fructicolain non-injured peaches. None of the products tested in curativetreatments was significantly effective in preventing the development ofbrown rot when the fungus was inoculated on injured fruits. None of theproducts tested was effective in the in vivo control of Rhizopus spp. Ozone gas at 0,1 ppm was not effective in controlling brown rot and soft rot in peaches.

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