Fruit rot caused by Phytophthora palmivora is one of the most important postharvest diseases affecting papaya and other economically important crops. The aim of this study was to evaluate the influence of temperature (15, 20, 25, 30 and 35 ºC), wetness period (0, 12, 24, 36, 48, 60, 72 h) and inoculum concentration (10¹ to 10(7) zoospores mL-1) of four P. palmivora isolates, from the south of Bahia (PP04 and PP20) and from the north of Espírito Santo (PP15 and PP16), on fruit rot severity in papaya cv. Sunrise Solo. The highest inoculum concentrations tested, 10(6) and 10(7) zoospores mL-1, caused the largest lesion areas in the fruits, increasing the infection severity for all four strains of P. palmivora tested. The severity of papaya fruit rot was significantly influenced by incubation temperature and fruit wetness period; the largest lesion areas were found on fruits exposed to 25ºC and 72 h wetness period. Under these conditions, the isolate PP04 was the most virulent since it caused larger lesions in the fruits (7126.29 mm²), compared to the remaining isolates. There was variation in virulence between the isolates from Bahia and Espirito Santo; the latter required a critical inoculum concentration (ICcri) to cause infection (10(4) zoospores mL-1), greater than that for the former (10³ zoospores mL-1).
Carica papaya; favorable environmental conditions; postharvest rot
