Rattail fescue (V. myuros or F. megalura) is a self-pollinating grassy weed that was originally introduced to the U.S. from Europe, having come from England prior to 1800. This weed was most likely a contaminant mixed into meadow fescue seed, and almost all of it was imported here from England prior to 1880. Although it’s a European native, it’s really of little importance over there. Now, however, it can be found all over the U.S. as well as in Alaska, Latin America, Canada, and Hawaii. It’s an annual type of grass that is reproduced from seeds. It has also become an exceptionally troublesome weed that’s found in a number of different habitats, like in cultivated crops, roadsides, orchards, and ditches. In addition, it’s definitely not a suitable livestock forage crop.
In fact, fescue didn’t take long to gain a bad reputation for causing health problems in livestock. It’s been found to cause three syndromes of fescue toxicosis, including elevated respiration rates and gangrene that would result in the loss of ears, hooves, and tails. This syndrome became known as “fescue foot” in New Zealand in 1949. The second syndrome was caused by the high rates of fertilizer in the fescue pastures, causing hard fat accumulations along bovine intestinal tracts, which resulted in a digestive upset as well as difficult births (aka fat necrosis). The third syndrome involved general failures in shedding their winter haircoats, intolerance to heat, reductions in milk production, and lower feed intake.
Each mature rattail fescue grassy weed can grow as big as two-feet tall and has a narrow upright stem with narrow leaves that are both folded and hairless with a tendency to droop. Their flowering heads can be up to eight inches long and appear to be flat and almost fan-like. This grassy weed’s little spikelets are alternating and flat with four to five flowers on each one.
This is an annual winter grass that prefers the cooler seasons and has become quite widespread all over the Pacific Northwest in the wheat production systems. It’s especially widespread all over California and grows in all kinds of habitats that range from annual grasslands and sagebrush to chaparral-mountain shrub, definitely preferring disturbed sites. Rattail fescue reduces the habitat of other native perennial grasses, forming dense mats of residue, which tend to be allelopathic to the wheat seedlings via a reduction in root and shoot elongation.
When rattail fescue forms residue mats, it can result in such an adverse effect on both shoot and root growth that it can create significant competition between the weed and wheat. This has been known to reduce crop yields by as much as 10 to 30 percent. One thing that has helped wheat growers with managing rattail fescue is the introduction of pyroxasulfone (Zidua and Anthem Flex) into the wheat systems recently. However, the growers must also start incorporating other management practices via the use of similar chemicals for providing effective long-term weed control.
For proper weed control, which is very important with this type of destructive weed, pre-emergents with herbicides are preferred for preventing the thick growth of these rattail fescue weeds. You can easily remove the individual plants by hand or use systemic herbicides for better results. Any chemical weed control application requires proper timing to get the results you want so pay attention to the directions. Prevention via crop rotation is highly recommended. Proper year-round weed control is needed to help keep this grassy weed off your lawn.