The Incidence of Fusarium graminearum in Wild Grasses is Associated With Rainfall and Cumulative Host Density in New York

Abstract

The movement of plant pathogens between cultivated and natural host communities can result in lost agricultural production and altered microbial or plant biodiversity. Fusarium graminearum incidence was studied in wild grass hosts for 3 years to better understand the ecology of this plant pathogen at the interface of crop fields and nonagricultural environments. Research sites (n = 23) were spread between regions of high and low agricultural production and included both agricultural and nonagricultural fields. Pathogen incidence in living grass spikes and senesced, overwintered stems varied between regions of New York and was lowest in a region with sparser agricultural production (P = 0.001). However, pathogen incidence within regions was similar at both agricultural and nonagricultural sites. The groundcover of crop and wild hosts within 1 km of sample sites were equally effective predictors of pathogen incidence, indicating either host group may drive pathogen spread. Rainfall in the 8 weeks preceding sample collection was strongly correlated with F. graminearum incidence in grasses, as well as an increased prevalence of F. graminearum in Fusarium spp. communities (P = 0.001). Grass species diversity was not associated with a reduction in pathogen incidence, and F. graminearum incidence did not vary among the most well-sampled grasses. These results indicate the pathogen colonizes and spreads in noncultivated grasses in a manner consistent with existing concepts of pathogen epidemiology in cereal crops. Increasing host acreage, whether cultivated or not, could drive the colonization of grasses in remote or protected environments, potentially altering their microbial communities.

Who is the culprit: Is pest infestation responsible for crop yield losses close to semi‐natural habitats?

“…( 2019 ), Fulcher et al. ( 2020 )) and Suproniene et al. ( 2019 ) observed a remarkable influence of weed patches to an increased incidence of Fusarium graminearum , the causal agent of Fusarium head blight, on wheat plants.…”

“…However, our study did not confirm this pattern for the year of investigation. One explanation could be that the incidence of Fusarium on noncrop grasses and the dispersal to the wheat plants is strongly affected by annual and regional environmental conditions, mainly by precipitation, humidity, and weed density (Fulcher et al., 2020 ). We assume that the relatively dry year 2016 influenced the abundance of the total fungal infection rates (here: median 5.6%) as well as the fungal population structures on wheat plants.…”

“…Yet, fungal leaf infection and herbivory of CLB were affected in different ways by the type and distance to a SNH whereas fungal seed infection remained unaffected of SNHs.The latter result is rather unexpected because several studies have shown that seed-inhabiting fungi can be associated with a variety of noncrop plants. Especially for phytopathogenic fungi of the genus Fusarium,Fulcher et al (2019), Fulcher et al (2020) andSuproniene et al (2019) observed a remarkable influence of weed patches to an increased incidence of Fusarium graminearum, the causal agent of Fusarium head blight, on wheat plants. The authors found a high Fusarium abundance on several noncrop grasses providing a permanent habitat for the fungi, especially in the overwin-…”