Germination of Conidia of Erysiphe cichoracearum

SUMMARYThe influence of several factors in the environment on germination of conidia of Erysiphe cichoracearum was studied. Pretreatment of infected host plant organs to remove nonviable conidia can improve germination percentages. Light was found to stimulate the germination of conidia at a temperature of 14 C. The highest percentages of conidial germination were obtained at 18 to 24 C. There was little germination or infection below 10 C and none at 32 C. Free water on leaf disk surfaces inhibited germination, while high relative humidities favored higher percentages of spore germination, there was some germination of conidia in CaCl2 chambers. A pH range of 6.6 to 7.0 favored a higher germination percentage, but germination occurred over the entire range tested.