Rattail fescue is introduced winter annual grass, with slim, tightly folded leaf blades less than 1/16 inch wide. Although the leaves appear smooth, the upper surface can be scabrous or covered with tiny hairs, only visible when magnified. The grass’s inflorescence is a narrow, compact spike-like panicle only 2-8 inches long (Figure 2). The plant typically grows from 4 inches – 2 feet in height. Rattail fescue only reproduces by seed and dispersion of seed is very near to the parent plant. Seed can be further dispersed if the seeds attach to animals’ fur or through mechanical processes.
Rattail fescue can be sensitive to extreme drought conditions and will thrive within higher moisture environments, however, rattail fescue can also thrive in low moisture environments, under poor, shallow acidic soils. The plant has excellent seedling vigor and can germinate immediately after the first autumn rainfall event. The roots of rattail fescue are fibrous and typically remain shallow within the soil. The dry tissue of rattail fescue breaks down slowly and can form dense mats if left unmanaged (Figure 3). Rattail fescue can be highly competitive with crops and can reduce yields10-30% (Dillon and Forcella 1984). Rattail fescue, like several other invasive winter annual grasses, is not readily grazed due to the awns that can injure the mouths of grazing animals.
Prevention is always the preferred and most effective method of controlling invasive plant species, but when an invasive annual such as rattail fescue has already established, the strategy should be to reduce seed production.
Rattail fescue is a major problem in no-till systems throughout the western United States. With the shallow root system, shallow tillage can be used for the management of rattail fescue. In no-till systems, operations using high disturbance hoe drills have had fewer problems than those using low-disturbance drills. Integrated weed management practices are always preferred to those that use one management practice. The use of targeted tillage, having a competitive crop planted and the use of targeted herbicides will be the optimal practice to manage rattail fescue populations.
There are no biological control agents for rattail fescue.
The timing of herbicides can be critical for rattail fescue management. In chemical fallow, the application of glyphosate prior to tillering can lead to ineffective control, however, applications at the 3-5 tillering stage can provide effective control. Several herbicides have been effective for the control of rattail fescue. The use of flufenacet+metribuzin, or pyroxasulfone preemergence and glyphosate, pyroxsulam, flucarbazone-sodium, mesosulfuron combinations postemergence as an effective control to rattail fescue populations. Always be aware of the herbicides you are using to avoid plant herbicide resistance. Additional information on rattail fescue management can be found within publication titled, Rattail Fescue: Biology and Management in Pacific Northwest Wheat Cropping Systems (PNW613).
Refer to the label for all herbicides. Always follow label directions prior to use.