FEBRUARY 2008

Washington State University
WHITMAN COUNTY EXTENSION

STEVE'S

Ventenata
Also Known As: wiregrass, hairgrass, North Africa grass, softbearded oat grass

Ventenata is not on the noxious weed list. Please report infestations to your county extension agent.

Ventenata (Ventenata dubia (Leers) Durieu) is native to central and southern Europe, Asia, and Africa. Although it is a relatively new invader, ventenata has established itself in a number of states in the United States and provinces in Canada. It is currently increasing its expansion across the Pacific Northwest and will probably continue to spread, particularly as a contaminant in grass seed.

Ventenata is an introduced tufted annual grass, with slim, erect culms extending 6-27 inches tall. Although the stem appears smooth, tiny hairs are visible when magnified. The leaf blades are flat but become in-rolled; they are usually smooth on the upper surfaces but rough underneath. The grass’s inflorescence is an open panicle and is yellowish-brown to yellow in color. The branches of the panicle often spread until they droop. Spikelets are near the branch tips and are stalked. Ventenata has twisted and abruptly bent awns (3/8 – 1 inch in length), located on the upper florets. The upper 1-2 florets are bisexual. Ventenata’s bent awns distinguish the plant from cheatgrass (Bromus tectorum), which has straight awns but otherwise appears very similar. Ventenata and cheatgrass are both annual grasses that grow to similar heights and have open panicles. However, cheatgrass flowers earlier in the season (May to June), while ventenata flowers from June to August.

Ventenata germinates best at moderate to high temperatures. The grass establishes in disturbed areas and is highly invasive in bluegrass, alfalfa, winter wheat, and range sites. When it infests crops, it can obstruct and even damage mechanical harvesting equipment, and is also known to cause loss of crop yield. Ventenata grass is unpalatable, so its spread into grazing land causes loss of forage.

Cultural/Mechanical/Biological: Little control information is available for this relatively new invader. Prevention is always the preferred and most effective method of controlling invasive plant species, but when an invasive annual such as ventenata has already established, the strategy should be to reduce seed production. Mechanical and physical control methods are generally ineffective since the grass tends to bend rather than cut. Biological control agents have not been developed.

Chemical: Herbicides can be effective in treating ventenata. Ventenata has shown resistance to glyphosate and sethoxydim (Weed Alert 2002). A study conducted in eastern Washington in 1997-1998 tested imazamox’s effectiveness in controlling ventenata in winter wheat crops. The study found that fall applications provided greatest control and winter wheat yields (1998 Weed Control Report 1998). Another eastern Washington study testing imazapic is in the early stages, but preliminary data shows 40-70% control from the spring application, with the undocumented fall application showing significantly greater control.

Refer to the label for all herbicides.
Always follow label directions prior to use.

Prescription Burning: Another possible control method is prescription burning; however, its effectiveness depends on the amount of litter accumulation prior to the fire and also the degree of litter consumption, since the seed bed is found in the litter layer. Further study is needed.

            Treated - 8oz per acre Plateau                                    Untreated          

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Questions: contact Steve Van Vleet or phone (509) 397-6290