Assessing the Efficacy of Preharvest Fungicide Applications to Control Postharvest Diseases of Florida Citrus

Abstract

<jats:p>Studies were conducted between November 1999 and April 2003 to evaluate the effectiveness of compounds applied preharvest for reducing postharvest decay on many types of fresh citrus (<jats:italic>Citrus</jats:italic> spp.) fruit. Commercially mature fruit were harvested two different times after the compounds were applied, degreened when necessary, washed, waxed (without fungicide), and then stored at 50 °F (10.0 °C) with 90% relative humidity. Compared to control (unsprayed) fruit, preharvest application of benomyl or thiophanate-methyl resulted in significantly (<jats:italic>P</jats:italic> &lt; 0.05) less decay of citrus fruit after storage in nine out of ten experiments, often reducing decay by about half. In one experiment, pyraclostrobin and phosphorous acid also significantly decreased total decay by 29% and 36%, respectively, after storage compared to the control. Only benomyl and thiophanate-methyl significantly reduced stem-end rot (SER; primarily <jats:italic>Diplodia natalensis</jats:italic> or <jats:italic>Phomopsis citri</jats:italic>) after storage, with an average of 65% less decay compared to the control. Though benomyl significantly reduced anthracnose (<jats:italic>Colletotrichum gloeosporioides</jats:italic>) in two of four tests with substantial (&gt;20%) infection and phosphorous acid significantly reduced it once, thiophanate-methyl did not significantly reduce the incidence of anthracnose postharvest. The data suggests that preharvest application of thiophanate-methyl may reduce postharvest SER and total decay similar to preharvest benomyl treatments.</jats:p>

Lasiodiplodia theobromae in Citrus Fruit (Diplodia Stem-End Rot)

“…If early season harvested fruit need ethylene degreening treatment or need to be held in packing houses at ambient temperature for longer than the normal holding time, preharvest application of appropriate fungicides in groves shortly before fruit harvesting could be practiced to help citrus postharvest disease management (Eckert and Eaks, 1989;Ritenour et al, 2004;Smilanick et al, 2006b). The benzimidazole fungicides benomyl and thiophanate methyl have been reported to be effective for the control of Diplodia stem-end rot and other postharvest diseases when these fungicides are sprayed on citrus trees shortly before harvest (Brown and McCornack, 1969;Brown and Albrigo, 1970;Brown, 1974;Ritenour et al, 2004;Salvatore and Ritenour, 2007;Zhang and Timmer, 2007).…”

Induced Resistance for Plant Disease Control

“…Field trials were conducted between 1999 and 2003 to evaluate effects of several chemicals, including the plant activators ASM, fosetyl-Al and phosphorous acid, on natural postharvest infections of citrus (Ritenour et al, 2004). Field trials were conducted between 1999 and 2003 to evaluate effects of several chemicals, including the plant activators ASM, fosetyl-Al and phosphorous acid, on natural postharvest infections of citrus (Ritenour et al, 2004).…”

Doenças pós-colheita em citros: potencial do Lentinula edodes, Agaricus blazei, ácido jasmônico, albedo (Citrus sinensis var. Valência) e flavedo (Citrus aurantifolia var. Tahiti) no controle e na indução de resistência

“…Redução superior a 50% na incidência de podridões pós-colheita, após o período de armazenamento a 10 ºC, foi observada em frutos cítricos que receberam aplicação de tiofanato metílico em pré-colheita (RITENOUR et al, 2004). Identificar e quantificar a contaminação fúngica presente nas distintas partes do packing-house, assim como estudar a presença de isolados resistentes é importante para se estabelecer riscos potenciais de danos e desenhar sistemas adequados de controle.…”