Etiología y epidemiología de la necrosis de flores y frutos juveniles del papayo (Carica papaya l.) en Guerrero, México

Flower necrosis, rot, and dropping of young fruits of the papaya (Carica papaya L.) are diseases with high incidence and which reduce productivity of commercial groves in Huamuxtitlán, Guerrero, Mexico. The objective of the present study was to determine the etiology and epidemiology of these diseases. Cladosporium sp. and Fusarium spp. were isolated from necrotic flowers and fruits, and in a smaller proportion, Alternaria sp. and Colletotrichum spp. The species Fusarium equiseti, F. chlamydosporum, Cladosporium cladosporoides and Alternaria alternate caused necrosis and flower abortion 8 d after inoculation (dai) and necrosis, rot and dropping of young fruits 15 dai. Colletotrichum gloeosporioides provoked necrotic lesions in 30 % of the inoculated flowers but did not cause symptoms in fruits. The population dynamic of spores of Alternaria spp. and Fusarium spp. in the air was studied in a plantation of papaya cv. Maradol from March 2007 to March 2008; the spores of both fungi were found from May to October, although the highest number was captured in May and September. The spores of Fusarium spp. were most abundant during the night hours (20:00 to 04:00 h) and those of Alternaria spp. between 12:00 and 14:00 h. Fusarium equiseti, F. chlamydosporum, Cladosporium cladosporioides and Alternaria alternata are pathogenic agents of the necrosis of flowers and dropping of young fruits of papaya in Huamuxtitlán, Guerrero, México. The propagules of Alternaria spp. and Fusarium spp. are dispersed in the environment of the study zone from May to October.