Spatial Distribution of Root and Crown Rot Fungi Associated With Winter Wheat in the North China Plain and Its Relationship With Climate Variables

The distribution frequency of pathogenic fungi associated with root and crown rot of winter wheat ( ) from 104 fields in the North China Plain was determined during the period from 2013 to 2016. The four most important species identified were (24.0% from roots; 33.7% from stems), (14.9% from roots; 27.8% from stems), (1.7% from roots; 4.4% from stems), and var. (9.8% from roots; 4.4% from stems). We observed that the recovered species varied with the agronomic zone. was predominant in regions 1 and 3, whereas , and were predominant in regions 2 and 4. The incidence of and was significantly different between regions 1 and 4, while no significant association was found in the distribution of the other species and the agronomic zones. A negative correlation between the frequency of occurrence of and mean annual precipitation during 2013-2016 ( = -0.71; < 0.01) in the North China Plain and a positive correlation between the mean annual precipitation during 2013-2016 and the frequency of occurrence of ( = 0.74; < 0.01) were observed. Several species were also found with low frequencies of ~2.1%-3.4 % ( , and ) and ~0.1%-1.3% ( , and ). In more than 93% of the fields, from the root and crown tissues of wheat, two or more root and crown rot species were isolated. The coexistence of spp. and in one field (65.4%) or in individual plants (11.6%) was more common than for the other species combinations. Moreover, this is the first report on the association between and root and crown rot of wheat. Our results would be useful in the framing guidelines for the management of root and crown rot fungi in wheat in different agronomic zones of the North China Plain.