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Isolation and Identification of Pathogens Causing Marigold (Tagetes erecta L.) Black Spot in Beijing, China

Chen, Dong‐liang, Cheng, Xi, Luo, Chang, Li, Ming‐yuan, Feng, Qian‐qian, Yan, Ji‐ye, Huang, Cong‐lin
Phytopathologische Zeitschrift 2016 v.164 no.7-8 pp. 547-553
Alternaria tagetica, Tagetes erecta, carrots, genes, greenhouses, leaves, pathogen identification, pathogens, planting, spores, stems, China
Black spot leads to great marigold losses worldwide. The disease is characterized by black spots on leaves and stems in its early stages, and the whole plant has black rot at the advanced stage. In this report, 6 of 217 Alternaria strains isolated from lesions of marigold plants in Beijing were randomly selected. The morphological characteristics and a pathogenic tree based on two protein‐coding genes (gpd and alt a 1) indicated that Alternaria tagetica is the causal agent of marigold black spot in Beijing. All six Alternaria strains could successfully re‐infect marigold, but they could not infect carrot or zinnia by either spore spray in a greenhouse or planting experiments in the epidemic area. This is the first report of the A. tagetica pathogen being isolated from marigold in Beijing.