In addition to cultural practices, dollar spot disease management requires frequent application of fungicides. Demethylation inhibitor (DMIs) fungicides are applied repeatedly to manage dollar spot in turfgrass systems. This facilitates reduction in DMI fungicide sensitivity among Clarireedia spp. populations. The objectives of this study were to (1) identify EC50 and relative mycelial growth (RMG) values for Clarireedia spp. across nine commercially available DMI fungicides, (2) determine the discriminatory dose for each of these fungicides, and (3) elucidate differences among isolates exhibiting varying degrees of sensitivity to propiconazole across all commercially available DMI fungicides. Discriminatory doses were determined to be 0.01 for propiconazole and prothioconazole, 0.1 for flutriafol and tebuconazole, and 1.0 µg active ingredient (a.i.) mL−1 potato dextrose agar for triadimefon, mefentrifluconazole, metconazole, triticonazole, and myclobutanil. Mefentrifluconazole completely inhibited mycelial growth of sensitive isolates. There were varying levels of mycelia suppression across highly insensitive isolates (RMG > 80%). Across highly insensitive isolates, prothioconazole provided the least suppression of growth, while mefentrifluconazole and myclobutanil provided the highest suppression of mycelial growth. However, none of the fungicides completely inhibited mycelial growth of the moderately sensitive and highly insensitive isolates. Results suggest variable suppression may exist among commercially available DMIs among sensitive and insensitive isolates of Clarireedia jacksonii.

中文翻译：

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Clarireedia jacksonii 的 DMI 杀菌剂的鉴别剂量测定和活性成分的菌丝生长变化


除了栽培实践外，美元斑病管理还需要经常使用杀菌剂。去甲基化抑制剂 （DMI） 杀菌剂被反复施用，以控制草坪草系统中的美元斑点。这有助于降低 Clarireedia spp. 种群对 DMI 杀菌剂的敏感性。本研究的目的是 （1） 确定九种市售 DMI 杀菌剂中 Clarireedia 属的 EC50 和相对菌丝生长 （RMG） 值，（2） 确定这些杀菌剂中每一种的鉴别剂量，以及 （3） 阐明在所有市售 DMI 杀菌剂中对丙环唑表现出不同程度敏感性的分离株之间的差异。丙环唑和丙硫菌唑的鉴别剂量为 0.01，氟三唑和戊唑醇为 0.1，三唑二唑、甲芬三氟康唑、甲康唑、曲替康唑和腈菌唑的鉴别剂量为 1.0 μg 活性成分 （a.i.） mL-1 马铃薯葡萄糖琼脂。甲芬氟康唑完全抑制敏感菌株的菌丝生长。在高度不敏感的分离株中，菌丝体抑制水平不同 （RMG > 80%）。在高度不敏感的分离株中，丙硫菌环唑对菌丝生长的抑制最小，而甲芬氟康唑和腈菌唑对菌丝生长的抑制作用最高。然而，没有一种杀菌剂完全抑制中度敏感和高度不敏感分离株的菌丝生长。结果表明，市售 DMI 中可能存在差异抑制，分别是 Clarireedia jacksonii 的敏感和不敏感分离株。