The question

Vulpia myuros (rat’s tail fescue, EPPO: VLPMY) has been increasingly reported in German arable fields. The species benefits from reduced tillage and has a rapid population dynamic driven by high seed production and a short-lived seed bank. The question: how widespread is it in Germany, at what infestation level does it occur, and how does it respond to current herbicide chemistries?

Part 1, Field monitoring

Between 2019 and 2025, Agris42 monitored approximately 2,100 fields across 14 federal states (12,000 ha; winter cereals, sugar beet, and maize). Of these, 276 geo-referenced observations of Vulpia myuros were recorded, a fraction compared to blackgrass (ALOMY, n = 17,094) and Italian ryegrass (LOLMU, n = 2,626). The geographic spread is narrow, concentrated in Sachsen, Sachsen-Anhalt, and Thüringen, with isolated finds elsewhere. Crucially, 76% of all VLPMY observations fall into infestation class 1, individual plants only. The majority of finds are in winter wheat, sugar beet, and winter rapeseed, often at field margins or marginal sites.

Part 2, Greenhouse efficacy testing

To assess the herbicide response of German Vulpia myuros populations, 24 biotypes were tested in the Agris42 greenhouse against three herbicide mode-of-action groups at their registered field rates: ACCase inhibitors (Pinoxaden, Clodinafop, Propaquizafop, Fenoxaprop, Cycloxydim, Clethodim), ALS inhibitors (Mesosulfuron, Nicosulfuron, Foramsulfuron, Pyroxsulam, Rimsulfuron), and EPSPS (Glyphosate). The trial used a complete block design with two replications, visual scoring at 28 days after treatment.

The results show a striking pattern: V. myuros has a natural tolerance to most ACCase inhibitors, Pinoxaden, Clodinafop, Propaquizafop, Fenoxaprop, and Cycloxydim all showed near-zero efficacy across all 24 biotypes. The exception is Clethodim, which achieved high control (~95–100%). ALS inhibitors consistently delivered high efficacy (85–100%) with low variability across biotypes. Glyphosate (EPSPS) likewise showed good control (~85–90%). Importantly, no signs of acquired resistance were detected in any of the 24 biotypes.

The conclusion

Vulpia myuros is currently not a problem weed in Germany. Infestation levels are low, geographic distribution is limited to marginal sites and field edges, and there are no signs of resistance development in any of the tested biotypes. The species remains controllable with ALS chemistry and Glyphosate. However, given its rapid population dynamics and adaptation to reduced tillage systems, it should remain a weed to watch, particularly where no-till or minimum tillage is practiced.