Brown leaf spot (BLS), caused by the fungus Clarohilum henningsii, is one of the most common leaf diseases in cassava, leading to losses in root yield due to the extensive defoliation of the plants. Despite this, BLS has been neglected and little is known about the disease. This study aimed to evaluate the ability of systemic fungicides (cyproconazole, thiophanate-methyl, pyraclostrobin, tebuconazole, azoxystrobin, and flutriafol) to inhibit the in vitro growth of C. henningsii isolates and to control BLS in cassava plants. In addition, we verified the effect of the fungicides on the plant physiology by measuring the chlorophyll a content. The results showed that the isolates were sensitive to all fungicides, as demonstrated by the low EC₅₀ (effective concentration of fungicide able to inhibit mycelial growth by 50%) values, which ranged from 0.06 to 0.43 μg.mL⁻¹. In addition, all fungicides were able to reduce the severity of BLS in cassava plants, but with different effectiveness. In general, flutriafol had the highest efficiency in reducing the disease severity under greenhouse and field conditions. Cassava plants treated with pyraclostrobin, azoxystrobin, and flutriafol had the highest increase of chlorophyll a content, which has not been reported in this crop. Based on our results, flutriafol is the most promising fungicide to control BLS in cassava, since it had the highest effectiveness in reducing the disease and provided the highest increase in the chlorophyll a content of the plants.

木耳香菇（Clarohilum henningsii）引起的褐斑病（BLS）是木薯中最常见的叶病之一，由于植物的大量脱叶而导致根系产量下降。尽管如此，BLS仍被忽略，对该病知之甚少。本研究的目的是评估全身杀真菌剂（环丙唑醇，甲基硫菌灵，唑菌胺酯，戊唑醇，嘧菌酯，粉唑醇和）的抑制的体外生长的能力C. henningsii在木薯植物隔离和控制BLS。此外，我们通过测量叶绿素a含量验证了杀菌剂对植物生理的影响。结果表明，分离株对所有杀菌剂均敏感，低EC ₅₀证明了这一点。（能够抑制菌丝体生长50％的有效浓度的杀真菌剂）值介于0.06至0.43μg.mL ^-1之间。此外，所有杀菌剂均能够降低木薯植物中BLS的严重性，但效果不同。通常，氟替莫酚在温室和田间条件下降低疾病严重程度的效率最高。用唑菌胺酯，嘧菌酯和氟三酚处理的木薯植株的叶绿素a含量增幅最高，尚未见该作物的报道。根据我们的研究结果，氟替莫非是控制木薯中BLS的最有希望的杀真菌剂，因为它在减少病害方面具有最高的功效，并且在植物中叶绿素a含量方面的增加最大。