Pathogenic characteristics and chemical control of soybean leaf anthracnose caused by Colletotrichum sojae newly found in Northeast China.

Soybean (Glycine max) leaf anthracnose, caused by diverse pathogenic agents, poses a significant threat to global soybean production. In 2025, a pathogenic fungus was isolated from symptomatic soybean leaves collected in a major soybean-producing region of China. Morphological and molecular characterization confirmed that the isolates belong to Colletotrichum sojae. To our knowledge, this is the first report of C. sojae causing soybean leaf anthracnose in Northeast China. Among 15 tested C. sojae isolates tested, moderately virulent strains were predominant, accounting for approximately 53.3%. Host range determination demonstrated that C. sojae could infect lentil, tomato, cowpea, peanut, kidney bean, broad bean, mung bean, and corn, but failed to infect red adzuki bean. Fungicide bioassays showed that tebuconazole and difenoconazole exhibited the highest inhibitory efficacy, with each fungicide achieving full mycelial growth inhibition at 0.05 mg·L⁻¹. Moreover, foliar spraying with tebuconazole at 0.00014 mg·L⁻¹ and difenoconazole at 0.0005 mg·L⁻¹ reduced disease incidence by roughly 76%. Therefore, intercropping of host and non-host plants, combined with the application of the aforementioned chemical fungicides, can be considered as effective strategies for controlling soybean leaf anthracnose. These results establish a scientific foundation for managing C. sojae-associated soybean leaf anthracnose in Northeast China.