Pathogen identification of Corynespora leaf spot on strawberry and its sensitivity to nine fungicides

The pathogen of a new strawberry leaf spot disease collected from Zhucheng city, Shandong Province was isolated and identified. Its pathogenicity was determined by indoor inoculation. Its susceptibility to 9 fungicides such as SYP-14288 was determined by mycelial growth rate method. The results showed that the pathogen was Corynespora cassiicola according to the morphological analysis and ITS phylogenetic analysis. The results also showed that SYP-14288 had a strong inhibitory effect on the mycelia growth of C. cassiicola, with an average EC₅₀ value of (0.27 ± 0.18) μg/mL, which could be used as the first choice for the control of strawberry leaf spot disease. The mean of EC₅₀ values were (0.66 ± 0.21) μg/mL, (0.85 ± 0.25) μg/mL, (1.4 ± 1.2) μg/mL, (1.8 ± 0.3) μg/mL, (3.8 ± 3.0) μg/mL and (4.5 ± 2.6) μg/mL for epoxiconazole, myclobutanil, prochloraz, difenoconazole, azoxystrobin and tebuconazole, respectively. Chlorothalonil and mancozeb had the lowest toxicity. The results have provided a reference for the control of Corynespora leaf spot on strawberry.