Relação entre a temperatura e o molhamento foliar no monocíclo da Sigatoka-negra

Abstract

The influence of temperature (21, 24, 27 and 30 °C) and leaf wetness duration (0, 12, 24, 48 and 72 hours) on the penetration of the causal agent of Black Sigatoka (Mycosphaerella fijiensis) was quantified under controlled environment. The area under disease progress curve (AUDPC) and the incidence were influenced by temperature and leaf wetness duration. There were significant differences (P=0.05) in AUDPC for the different temperatures, as well as a significant interaction (P=0.05) between temperatures and leaf wetness. Symptoms were observed at all temperatures; however, higher AUDPC was observed for inoculated leaves kept at 24 and 27°C, from 48 hours of leaf wetness. At temperatures of 21°C and 30°C, the incidence of Black Sigatoka was low. The minimum leaf wetness duration for the disease progress was 24 hours. Symptoms of Black Sigatoka were not observed for inoculated leaves with 0 and 12-hour leaf wetness at all temperatures. After 5 days in humid chamber, all asymptomatic leaves presented symptoms characteristic of Black Sigatoka, demonstrating that the conidia inoculated in the leaves kept viable for a certain period in the absence of free water on the leaf.