引起西洋参锈腐病的Ilyonectria属4种病原菌的生物学特性及其对不同杀菌剂的敏感性

 Ilyonectria属真菌是引起西洋参锈腐病的主要病原菌,每年给西洋参生产造成重要经济损失。本文选取分离自我国吉林省及山东省栽培的西洋参的I. mors-panacis、I. robusta、I. vredehoekensis及I. communis 4种病原菌,通过平板培养,测定它们在不同培养基、温度、碳源、氮源和光照条件下菌丝生长和产孢量;采用生长速率法测定对6种常用杀菌剂的敏感性。生物学试验结果表明:Czapek培养基为Ilyonectria spp.菌丝生长的最适培养基,PDA、OA和CMA培养基有利于产孢;菌丝生长最适碳源和氮源分别是可溶性淀粉和硝态氮,不同碳源对各菌株产孢的作用不同,最适产孢氮源为硫酸铵;I. vredehoekensis最适生长温度为25 ℃,I. robusta为20～25 ℃,其他2种菌则为20 ℃,产孢最适温度范围为15～20 ℃;黑暗条件适宜供试菌的生长,全光照有利于I. mors-panacis和I. robusta产孢,但不利于I. vredehoekensis和I. communis产孢。药剂试验结果表明:同一杀菌剂对4种病菌的作用存在差异,在供试的6种杀菌剂中,4种病菌对多菌灵最为敏感(EC₅₀<0.5 μg·mL^-1),其次是戊唑醇(EC₅₀<15 μg·mL^-1),恶霉灵的抑制效果最差(EC₅₀>960 μg·mL^-1)。上述研究结果为了解西洋参锈腐病菌Ilyonectria的环境适应性及防治策略提供了有益参考。

Biological characteristics and fungicide sensitivity of four Ilyonectria species causing root rot on American ginseng

Several species of Ilyonectria are the main pathogens causing root rot of American ginseng,which are responsible for significant economic loss on the production of American ginseng. In this paper, four species of Ilyonectria, including I. mors-panacis, I. robusta, I. vredehoekensis and I. communis from diseased American ginseng in Jilin and Shandong provinces, were selected to compare their biological characteristics and fungicide sensitivities. Mycelial growth and sporulation of the four species were measured under different media, temperatures, carbon and nitrogen sources, and light conditions by plate culture method, respectively. The sensitivities of the tested strains to six common fungicides were determined by mycelial growth rate method. The optimum medium for mycelial growth of the four Ilyonectria species was Czapek while PDA, OA and CMA were more favorable for sporulation. The optimum carbon and nitrogen sources for mycelial growth were soluble starch and nitrate nitrogen, respectively. The optimum carbon source for sporulation were different among different species, and the optimum nitrogen source was (NH₄)₂SO₄. The optimum temperature for mycelial growth of I. vredehoekensis was 25 ℃, and that of I. robusta was from 20-25 ℃. It was 20 ℃ for the other species. While the optimum temperature range for sporulation was 15-20 ℃. All the tested strains were favorable to grow under dark conditions, and light had effects on sporulation. There was different effect of the same fungicide on the four tes-ted species. Among the six tested fungicides, all the tested Ilyonectria species were more sensitive to carbendazim with EC₅₀<0.5 μg·mL^-1, followed by tebuconazole with EC₅₀<15 μg·mL^-1. The inhibitory effect of hymexazol was worst with EC₅₀>960 μg·mL^-1. The present results give some new knowledge about characteristics of the four tested Ilyonectria species and provide reference on fungicides selection for the control of American ginseng root rot.