According to the results of disease investigation in field and detached Ginkgo leaves inoculation with Phytophthora nicotianae in lab, relative humidity 90%~100% and temperature 28~30℃ were the best cond i t i ons for the deve I opment of G i nkgo b I i ght. When the different age detached Ginkgo leaves were inoculated with P. nicotianae, the results show that the elder leaves were, the lower disease incidence occurred and the slower spreading speed of disease development had, and vice versa. Wh...