Plant Pathology (2020) 69, 1083-1092

Hui Feng, Jiajia Chen, Ze Yu, Ke Li, Zhe Li, Yaxin Li, Zhe Sun, Yuanchao Wang, Wenwu Ye and Xiaobo Zheng (2020)
Pathogenicity and fungicide sensitivity of Pythium and Phytopythium spp. associated with soybean in the Huang-Huai region of China
Plant Pathology 69 (6), 1083-1092
Abstract: Pythium and Phytopythium spp. cause seed decay, damping off, and root rot in soybean, wheat, and many other crops. However, their diversity and importance as pathogens, particularly in different crop rotation systems, are largely unknown. A survey was conducted in the Huang-Huai region, one of the main areas of soybean–wheat rotation farming in China. In 2016–2018, we collected 300 soybean seedlings and 150 field soil samples from several representative locations, and identified 26 Pythium and 6 Phytopythium spp. from 212 isolates, based on internal transcribed spacer 2 (ITS2) and cytochrome oxidase subunit 1 sequences. The pathogenicity of these isolates was evaluated by growing soybean and wheat seeds in dishes and pots containing oomycete cultures. We found that 12 Pythium spp. (but no Phytopythium spp.) showed high pathogenicity on soybean and/or wheat, and nine of them (75%) were highly pathogenic on both crops. Among the nine species, Pythium spinosum , Pythium ultimum , Pythium species 1 (tentatively designated as 'Candidatus Pythium huanghuaiense '), Pythium aphanidermatum , and Pythium myriotylum were highly abundant among all isolates (15%, 10%, 9%, 8%, and 5%, respectively). Nine species were selected for testing of sensitivity to the fungicides metalaxyl and mefenoxam. The EC₅₀ values were all less than 10 μg/ml, indicating little resistance. Minimum inhibitory concentration values indicated isolates were about twice as sensitive to mefenoxam as to metalaxyl. These results provide a systematic understanding of Pythium and Phytopythium species associated with soybean in the Huang-Huai region, which is important for disease management and breeding programmes.
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Link to article at publishers website
Database assignments for author(s): Yuan-Chao Wang

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution
pesticide resistance of pest

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Globisporangium ultimum	Soybean (Glycine max)	China (NE)
	Pythium aphanidermatum	Soybean (Glycine max)	China (NE)
	Globisporangium spinosum	Soybean (Glycine max)	China (NE)
	Pythium myriotylum	Soybean (Glycine max)	China (NE)