Zhu Shusheng, Liu Pengfei, Liu Xili, Li Jianqiang, Yuan Shankui, Si Naiguo
Department of Plant Pathology, China Agricultural University, Beijing 100094, China.
Pest Manag Sci. 2008 Mar;64(3):255-61. doi: 10.1002/ps.1515.
The oomycete fungicide flumorph is a recently introduced carboxylic acid amide (CAA) fungicide. In order to evaluate the risk of developing field resistance to flumorph, the authors compared it with dimethomorph and azoxystrobin with respect to the ease of obtaining resistant isolates to these fungicides, the level of resistance and their fitness in the laboratory.
Mutants with a high level of resistance to azoxystrobin were isolated readily by adaptation and UV irradiation, and their fitness was as good as that of the parent isolates. Attempts to generate mutants of Pseudoperonospora cubensis (Burk. & MA Curtis) Rostovsev resistant to flumorph and dimethomorph by sporangia adaptation on fungicide-treated leaves were unsuccessful. However, moderately resistant mutants were isolated using UV mutagenesis, but their resistance level [maximum resistance factor (MRF) < 100] was much lower than that of the azoxystrobin-resistant mutant (MRF = 733). With the exception of stability of resistance, all mutants showed low pathogenicity and sporulation compared with wild-type isolates and azoxystrobin-resistant mutants. There is cross-resistance between flumorph and dimethomorph, suggesting that they have the same resistance mechanism.
The above results suggest that the resistance risk of flumorph may be similar to that of dimethomorph but lower than that of azoxystrobin and can be classified as moderate. Thus, it can be managed by appropriate product use strategies.
卵菌纲杀菌剂氟吗啉是一种最近引入的羧酸酰胺（CAA）类杀菌剂。为了评估氟吗啉产生田间抗性的风险，作者将其与烯酰吗啉和嘧菌酯在获得对这些杀菌剂抗性分离株的难易程度、抗性水平及其在实验室中的适合度方面进行了比较。
通过驯化和紫外线照射很容易分离出对嘧菌酯具有高抗性的突变体，并且它们的适合度与亲本分离株相当。通过在经杀菌剂处理的叶片上进行孢子囊驯化来产生对氟吗啉和烯酰吗啉具有抗性的古巴假霜霉菌（Burk. & MA Curtis）Rostovsev突变体的尝试未成功。然而，使用紫外线诱变分离出了中度抗性突变体，但其抗性水平[最大抗性因子（MRF）<100]远低于对嘧菌酯抗性突变体（MRF = 733）。除了抗性稳定性外，与野生型分离株和对嘧菌酯抗性突变体相比，所有突变体的致病性和产孢量均较低。氟吗啉和烯酰吗啉之间存在交叉抗性，表明它们具有相同的抗性机制。
上述结果表明，氟吗啉的抗性风险可能与烯酰吗啉相似，但低于嘧菌酯，可归类为中度。因此，可以通过适当的产品使用策略进行管理。
