Metalaxyl-Resistant Isolates of Phytophthora nicotianae: Occurrence, Sensitivity, and Competitive Parasitic Ability on Citrus.
Metalaxyl-Resistant Isolates of Phytophthora nicotianae: Occurrence, Sensitivity, and Competitive Parasitic Ability on Citrus.
复制标题
DOI：
10.1094/pdis.1998.82.2.254
复制
发表时间：
1998-02
期刊：
影响因子：
4.5
通讯作者：
L. W. Timmer;J. Graham;S. Zitko
中科院分区：
文献类型：
--
作者：
L. W. Timmer;J. Graham;S. Zitko
烟草疫霉菌从11个苗圃点中的8个回收，在8个阳性点中的6个检测到甲霜灵抗性菌株。耐药菌株占这些地点人口的31%至59%。大多数抗性菌株在100 μg/ml的甲霜灵存在下生长良好，而敏感菌株在1.0 μg/ml下不生长。一些来自成熟柑橘格罗夫斯林的菌株的敏感性居中。在温室试验中，甲霜灵灌药未能控制抗性菌株，但三乙膦酸铝通常有效。采用替代系列技术比较了温室试验中抗性菌株和敏感菌株的相对竞争能力。结果根据所用的分离株而不同，但至少有一些甲霜灵耐药分离株能够在不存在甲霜灵的情况下与敏感分离株进行有利的竞争。在一项田间试验中，即使在2.5年没有使用甲霜灵杀真菌剂的情况下，仍有很高比例的种群对甲霜灵保持抗药性。在苗圃中过量使用甲霜灵，降低了该产品在佛罗里达格罗夫斯园的未来效用。
Phytophthora nicotianae was recovered from 8 of 11 nursery sites, and metalaxyl-resistant isolates were detected at 6 of the 8 positive sites. Resistant isolates comprised 31 to 59% of the population at those sites. Most resistant isolates grew well in the presence of 100 μg/ml of metalaxyl, whereas sensitive isolates did not grow at 1.0 μg/ml. Some isolates from mature citrus groves were intermediate in their sensitivity. Metalaxyl-drench treatments failed to control resistant isolates in greenhouse tests, but fosetyl-Al was usually effective. The replacement series technique was used to compare the relative competitive ability of resistant and sensitive isolates in greenhouse tests. Results varied according to the isolate used, but at least some metalaxyl-resistant isolates were able to compete favorably with sensitive isolates in the absence of metalaxyl. In a field test, a high percentage of the population remained resistant to metalaxyl even after 2.5 years without treatment with this fungicide. Excessive use of metalaxyl in nursery situations has reduced the future utility of the product in Florida citrus groves.