The effect of temperature, leaf wetness and light on development of grapevine rust

Abstract

The effects of temperature, leaf wetness duration, and light regimes on infection and the effect of temperature on latent period of Phakopsora euvitis (grapevine rust) on cv. Niagara Rosada grapevine (Vitis labrusca) was investigated. Potted transplants were spray-inoculated with an aqueous spore suspension and exposed to temperatures of 15, 20, 25, or 30 °C and wetness periods of 0, 3, 6, 12, or 24 h (under controlled environment conditions). Duration of leaf wetness and temperature both had significant effects on infection. A minimum of 6 h of continuous leaf wetness was required for infection of P. euvitis at temperatures of 15, 20, and 25 °C. Maximum infection occurred with a leaf wetness duration of 12 to 24 h at 20 °C. Infection did not occur at 30 °C regardless of leaf wetness period. A multiple regression model was developed describing infection based on temperature and leaf wetness duration (R 2 = 0.78). Light regimes during the initial 24-h leaf wetness period affected infection. The latent period was 13 days at 15 °C, 7 days at 20–25 °C, and 8 days at 30 °C. The results of this study describe conditions required for the development of grapevine rust epidemics.