The effect of temperature (15, 20, 25 and 28 ºC), wetness period (0, 6, 12, 24, 48 and 72 hours) and conidia concentration (0, 1x10², 1x10³, 1x10(4), 1x10(5) and 1x10(6) conidia/mL-1) on the incidence and severity of gray mold caused by Amphobotrys ricini in castor bean (Ricinus communis) bunches were evaluated. The conidia concentration effect was evaluated fixing the temperature at 25ºC and the wetness duration at 48 hour. The temperature and wetness duration were evaluated fixing the conidial concentration at 1x10(5) conidia mL-1. The plants were evaluated as to the incidence of fruit wiht symptons and severity in each bunch. The area under incidence progress curve (AUIPC) and under severity progress curve (AUSPC) was calculated, and the results submitted to variance and regression analysis. There was a significant difference for the different concentrations of conidia, for the temperatures and for the wetness period. There was significant interaction between temperature and the wetness period. With the increased concentrations of conidia, both the incidence and the severity of the gray mold showed increases until the 10(5) conidia mL-1 concentration. There was an increase of AUIPC and AUSPC for the wetness period increase and the temperature. There were no symptoms in the absence of wetness.
Ricinus communis; Amphobotrisricini; epidemiology; plant disease; infection conditions
