Laboratory toxicity of nine fungicides against Neopestalotiopsis clavispora

Neopestalotiopsis leaf spot is a new disease on strawberry. The pathogens of the new strawberry leaf spot disease from Changping district, Beijing, Zhucheng city, Shandong Province, Baoshan city, Yunnan Province, Huizhou city, Guangdong Province and other regions were isolated and identified. The pathogen was identified by morphological analysis and ITS phylogenetic analysis. Sensitivities of 8 isolates to 8 commonly used fungicides and SYP-14288 were determined by indoor inoculation. The results showed that the pathogen was Neopestalotiopsis clavispora. SYP-14288 had a strong inhibitory effect on the mycelia growth of 8 isolates of N. clavispora, with an average EC₅₀ value of (0.004 ± 0.002) μg/mL, which could be used as the first choice for the control of strawberry leaf spot disease. The mean of EC₅₀ values were 0.006-0.803 μg/mL for prochloraz, azoxystrobin, tebuconazole, epoxiconazole, difenoconazole, and myclobutanil, respectively. Chlorothalonil exhibited lower toxicity. while mancozeb had the lowest inhibitory activity. Those results are important for the rational application of fungicides in the chemical control of Neopestalotiopsis leaf spot, a new disease of strawberry.