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Poster Session: Biology and Disease Management - Chemical Control

226-P

Sensitivities of fungal pathogens of pomegranate (Punica granatum L.) to seven different fungicides..
A. N. KC (1), G. Vallad (1)
(1) University of Florida, Wimauma, FL, U.S.A.

Recent surveys identified Neofusicoccum parvum, Lasiodiplodia theobromae, and two Colletotrichum sp. as major pathogens of pomegranate in Florida. The in vitro sensitivity of these pathogens to fungicides pyraclostrobin, tebuconazole, thiophanate methyl, pyrimethanil, mancozeb, boscalid, and copper sulfate was determined. Three isolates of each pathogen were tested against six different concentrations of each fungicide and replicated three times. The effective concentration to reduce radial growth by 50% (EC50) was calculated for each pathogen-fungicide combination. Effect of salicylhydroxamic acid (SHAM) on the sensitivity of each pathogen to pyraclostrobin was also assessed. Two Colletotrichum sp. and N. parvum were sensitive to pyraclostrobin with average EC50 value of 0.66 µg/ml. Isolates of L. theobromae were not sensitive to pyraclostrobin (EC50 > 100) and addition of SHAM significantly increased their sensitivity (P < 0.001) with average value of 0.19 µg/ml. All species, except Colletotrichum sp. (EC50 for thiophanate methyl, pyrimethanil and mancozeb > 50 µg/ml), were sensitive to tebuconazole, thiophanate methyl, pyrimethanil, and mancozeb. None of the tested species were sensitive to boscalid or copper compound (EC50 > 100). This study provides a preliminary result to the effectiveness of different fungicides to the major diseases of pomegranate in Florida. Additional disease assays and field trials to evaluate fungicide efficacy are in progress.