Postharvest fludioxonil dip protects ‘Arkin’ carambola (Averrhoa carambola L.) from Dothiorella fruit rot

Abstract

South Florida has approximately 200 acres of commercial carambola worth an estimated $9.5 million annually. ‘Arkin’ carambola is typically harvested and then stored at 41 to 55 °F and 95% relative humidity. Prior to storage or packing, fruit are dipped in a 1% to 2% chlorine solution to remove a superfi cial blackish discoloration on the peel caused by Peltaster spp. More recently, fruit rot consisting of a Dothiorella spp. has become a problem in commercial carambola packinghouses, causing losses of up to 75% of packed fruit. Light brown streaks on the peel surface typically expand as the disease progresses, resulting in collapse of the pulp and splitting of the peel. An investigation to determine the effect of dipping fruit in chlorine and/or fl udioxonil was initiated to determine if chlorine dip caused an increase in disease progression and if fl udioxonil stopped or prevented disease progression. Fresh and stored (2 weeks at 48 °F) ‘Arkin’ carambola fruit were postharvest treated in 2007 and 2008. In 2007, treatments included dipping in chlorine (CH) or fl udioxonil (FL), dip in CH alone, FL-low rate, FL-high rate, CH dip followed by FL-low, CH dip followed by FL-high, as well as untreated controls. In 2008, treatments included dip in CH alone, FL-low, FL-high, or dipping in a mixture of CH-FL-high, plus controls. After treatment all fruit were placed in polyethylene bags and stored at 52 to 55 °F and periodically assessed for fruit rot symptoms. In general, pre-stored fruit developed fruit rot symptoms earlier than freshly picked fruit. Non-treated and CH treated fruit developed fruit rot symptoms earlier than fruit treated with FL, CH followed by FL, and CH-FL high treated fruit.