台灣山葵地上部之真菌病害種類與發生調查

Abstract

Leaf spot of globe amaranth was first noticed at San-chi villa, Taipei county in Taiwan in 1998. This disease was proved to be caused by Nimbya gomphre n a e in this study. The pathogen infected Gomphrena globosa cv. Buddy and cv. Globosa readily, but not G. haageana cv. Orange and cv. Strawberry. This may be due to the difference of the leaf structures, i.e. intensity of vein, trichome and length of trichome. When spore suspensions were inoculated on the leaves of globe amaranth, conidia produced germ tubes and formed appressoria to penetrate into host directly. Infecting mycelia grew intracellularly and flourishingly within host tissue. Six days after inoculation, mycelia emerged from leaf surface through stomata. The temperature relevant for the infection of the pathogen ranged from 16 to 32℃. High temperature (i.e. 32℃) was favorable for the development of the disease. This pathogen sporulated significantly (P=0.05) more on carrot- agar and V8 medium than on other media. Screening of efficient fungicide in vitro, pyrifenox showed the best potential to inhibit the mycelial growth of N. gomphrenae. Spraying 10 ppm pyrifenox on leaves of globe amaranth reduced significantly (P=0.05) the development of the disease.