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

Abstract

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Distance to semi‐natural habitats matters for arbuscular mycorrhizal fungi in wheat roots and wheat performance in a temperate agricultural landscape

“…Weed abundance turned out to be a key explanatory variable for wheat biomass at flowering and at final harvest and grain yield in the random forest analyses. Our results for grain yield confirm Raatz et al (2021), who show negative effects of weed abundance for grain yields from experimental plots along the same transects as used for the present study at 1 and 5 m distances from semi-natural habitats. However, Raatz et al (2021) studied wheat plants that they sowed into the farmers' fields while we harvested wheat plants sown by the farmers.…”

“…Our results for grain yield confirm Raatz et al (2021), who show negative effects of weed abundance for grain yields from experimental plots along the same transects as used for the present study at 1 and 5 m distances from semi-natural habitats. However, Raatz et al (2021) studied wheat plants that they sowed into the farmers' fields while we harvested wheat plants sown by the farmers. Incidental plants, like weeds, compete with crops for space, nutrients, water and light (Zimdahl, 2004) and hence can reduce crop biomass and grain yield effectively, especially close to semi-natural habitats where herbicides could not be sprayed due to nature protection regulations (Baer et al, 2018).…”

“…Low or no application of plant protection measures against pests, like fungi and herbivores, close to semi-natural patches may have caused increased pest infestations in vicinity to hedgerows and kettle holes, as well as pests from neighbouring semi-natural habitats can spill over into agricultural fields. Nonetheless, Raatz et al (2021) showed no effect of fungal seed, fungal leaf pathogens and herbivory of cereal leaf beetles on grain yield in the same winter-wheat transects as in this study. However, there are other wheat pests that could have been the culprit for reduced yield close to semi-natural habitats, for example, aphids.…”

“…Therefore, we suggest that the AM fungal root colonisation gradient could mainly be a result of an agricultural management gradient along the transects. Raatz et al(2021) showed greater weed abundances close to kettle holes and hedgerows at the same transects and during the same year which they suggest being the result of reduced herbicide application near semi‐natural habitats. Many weed species are hosts of AM fungi (Vatovec et al, 2005).…”

Arable Weeds at the Edges of Kettle Holes as Overwintering Habitat for Phytopathogenic Fungi

“…Water-filled kettle holes, which are natural ponds with <1 ha area [32], act as specific NLE that influence organisms in the bordering zones affected by soil moisture and air humidity. Due to the combined effect of the different types of plants in and around these structures and the increased surrounding humidity, kettle holes are regarded as hot spots for biodiversity [31,[33][34][35] and as particularly attractive living habitats for amphibians, insects, and breeding birds. Furthermore, kettle holes in Germany are protected areas by law (Gesetz über Naturschutz und Landschaftspflege ( §32 BbgNatSchG)) [36].…”