Medusahead Grass – invasive species that may come to western Nebraska-Panhandle Perspective

By Gary Stone, Extension Educator, Panhandle R&E Center, Scottsbluff

Early Detection and Rapid Response (EDRR) is a concept to identify potential invasive species prior to or just as the invasive is becoming established. An integrated pest management plan can be developed to manage, contain and eradicate the invasive species before it can spread further, avoiding costly, long-term control efforts.

Two invasive grasses, Ventenata and Medusahead, have been identified in parts of Wyoming. Both are slowly spreading east. While neither have been identified in Nebraska, it’s important to be aware of what these grasses look like, how they spread and be ready to deal with them should they show up in Nebraska.

If they would become established in the Pine Ridge area or the Sandhills, they could be devastating to the ecology and range production.

This article is about Medusahead, also known as Medusahead Wildrye, Medusahead rye, and rough Medusahead. Its scientific name is Taeniatherum caput-medusae (L.) Nevski, and it is of the Poaceae / Gramineae family.

Originating in Eurasia and the Mediterranean area, it was first reported in North America in the 1880s and now occupies more than 2.3 million acres in 17 western states.

Medusahead is an exotic, invasive, self-pollinated winter annual grass that germinates in the fall, overwinters as a seedling, and can have multiple flushes. It is typically 6 to 20 inches tall with distinct bristly seed heads.

Multiple stems can emerge from the base of the plant, each producing a single seed head. Each seed head may contain 20 or more seeds. Awns protrude upward and outward, with a twisting appearance.  Seed heads are similar in appearance to Bottlebrush Squirreltail (Elymus elymoides) and Foxtail Barley (Hordeum jubatum), but the Medusahead seed heads do not disarticulate (fall apart).

Foliage is bright green and upright. Seed longevity is two to three years. Medusahead matures two to four weeks later than most annual grasses. It has been shown to displace cheatgrass.

Medusahead produces a lot of thatch, which has a high silica content, is slow to decay, and also is highly flammable. While the thatch acts a barrier to other plant species’ germination and establishment, Medusahead seedlings thrive in this environment.

Medusahead seed can be carried long distances by wind, water, animals and human activities. The Medusahead seed awns have small barbs that help the seed adhere to clothing and hair of animals or other plant parts that may move with the wind.

The high silica content in Medusahead makes it a less desirable forage. It can be grazed early, prior to seed head formation – timing is important. The seed heads contain stiff glumes that can cause damage to the eyes and mouths of grazing animals and pets.

Proper grazing management practices and maintaining a diverse rangeland plant community are very important in preventing establishment of Medusahead.

Burning can reduce the thatch layer and seed levels, but can also reduce the number of desirable plants and seed.  Hand pulling and removal in small sites can be effective. Rotary mowing Medusahead in the early flowering stage before viable seed can be produced can reduce seed production. Revegetation must be carefully considered due to timing and precipitation events needed for germination of the desirable species. 

Chemical applications can be effective, but costly. A number of herbicides are labeled for Medusahead management, including Glyphosate, Imazapic, Aminopyralid (certain states), and other products. Be sure to read, understand and follow all label directions. Application timing can be critical for proper control expectations, and follow-up treatments may be required. The site and crop to be treated must be on the label.

An integrated management approach is required for control of Medusahead. Prevention is the best means to achieve this goal. Utilizing more than one management option will have a greater effect than using a single option.

Combining different grazing strategies, implementing prescribed burns, timely mowing and chemical applications will be required. Monitoring and follow-up treatments are required to keep the Medusahead in check and eliminated.