[Potential evaluation of 40% prothioconazole-tebuconazole suspension concentrate for resistance management of Alternaria spp. causing Alternaria leaf spot of ginseng].
摘要
Forty percent prothioconazole-tebuconazole suspension concentrate(SC) has been registered to control multiple crop diseases in China. This study aims to evaluate its efficacy for the control of Alternaria leaf spot of ginseng, so as to lay the foundation for the management of resistance of Alternaria spp. causing Alternaria leaf spot of ginseng to fungicides. The study first detected its antifungal activity against three species(A. alternata, A. panax, and A. tenuissima) and biochemical activity against A. alternata and then determined its efficacy against Alternaria leaf spot of ginseng in vitro. Field experiments lasting for one year at three locations were conducted to evaluate its field efficacy against Alternaria leaf spot of ginseng. Spearman's correlation analysis was used to determine the cross-resistance of 40% prothioconazole-tebuconazole SC with eight commonly used fungicides. The results showed that prothioconazole-tebuconazole had a good inhibitory effect on mycelial growth and spore germination of the three Alternaria species, and the inhibitory effect on mycelial growth was stronger than that on spore germination. The treatment with prothioconazole-tebuconazole at the concentrations of 0.1, 1.0, and 10.0 μg·mL~(-1) resulted in deformity of mycelia, shortened germ tubes of conidia, reduced content of DNA and soluble proteins, and decreased permeability of cell membrane of A. alternata. Under in vitro conditions, the protective and curative effects of 40% prothioconazole-tebuconazole SC in the concentration range of 50-150 μg·mL~(-1) on Alternaria leaf spot of ginseng were 65.45%-100.00% and 65.58%-96.36%, respectively, which were significantly better than those of tebuconazole at the same concentration. There was no cross-resistance between prothioconazole-tebuconazole and the eight fungicides(difenoconazole, propiconazole, tebuconazole, iprodione, pyraclostrobin, azoxystrobin, kresoxim-methyl, and mancozeb). These eight fungicides were widely used to