Pathogenicity Identification of Phytophthora nicotianae Causing Konjac Disease in Yunnan, China

Purpose In order to provide the theoretical foundation for prevention and control of konjac blight causing by Phytophthora nicotianae, the pathogenicity of Phytophthora should be determined.

Method Five Phytophthora strains were tested using inoculation in vitro and in vivo method in laboratory and greenhouse conditions.

Results Five strains had the similar pathogenicity to konjac, and the disease incidence reach 100%. The pathogenicity of P. nicotianae to leaves (disease index 98.33) and root (disease index 94.07) were significantly higher than seeds bulbs (disease index 78.33) and stem (disease index 71.11) in the laboratory. Besides, red pepper, soybean root, potato leaf and tobacco stem base were inoculated with Ps1 strains respectively, clear spots were found in different hosts, and P. nicotianae was the strongest pathogenic to potato (disease index 60.67) and the weakest pathogenic to soybean (disease index 32.59).

Conclusions The P. nicotianae can not only infect konjac, but also infect other host.