Identification and Management of Colletotrichum acutatum on Immature Bell Peppers

Abstract

Farmers in northwestern Ohio reported severe losses due to anthracnose in immature (green) bell pepper as early as 1998. Two fungal isolates (AN1 and AN2) were recovered from immature fruit showing severe anthracnose symptoms. The pathogen was identified as Colletotrichum acutatum based on morphological and cultural characteristics, polymerase chain reaction (PCR) assay with the C. acutatum species-specific primer (CaInt2), and nucleotide sequencing. Isolate AN1 was pathogenic on immature pepper, tomato, and strawberry. Twenty-two bell pepper cultivars evaluated in field trials were all susceptible to C. acutatum AN1 and AN2, but the degree of susceptibility varied among cultivars. ‘Crusader’, ‘Valiant’, and ‘ACX229’ were the most susceptible, while ‘North Star’ and ‘Paladin’ were least susceptible. The fungicides pyraclostrobin (Cabrio) alternated with manganese ethylenebisdithiocarbamate (Manex), chlorothalonil (Bravo Ultrex) alone, Manex plus copper hydroxide (Kocide 2000), and pyraclostrobin + boscalid (BAS 516 = Pristine) alternated with Manex significantly reduced anthracnose incidence and intensity in bell peppers compared with the untreated control.