No abstract

Smooth brome and Kentucky bluegrass are introduced cool-season perennial grasses known to invade grasslands throughout North America. During the fall of 2005 and spring of 2006, we implemented a restoration study at six native prairie sites in eastern South Dakota that have been invaded by smooth brome and Kentucky bluegrass. Treatments included five herbicide combinations, a fall prescribed burn, and an untreated control to determine the potential of each for renovation of invaded native grasslands. Herbicide treatments tested were sulfosulfuron, imazapyr, imazapic + sulfosulfuron, and imazapyr + imazapic, and were applied in late September 2005 and mid-May 2006. Untreated control plots averaged 64% (± 3.1) smooth brome cover and 38% (± 5.5) Kentucky bluegrass cover after the third growing season. Smooth brome cover in herbicide treated plots ranged from 6 to 23% and Kentucky bluegrass cover ranged from 15 to 35% after the third growing season. Smooth brome cover was 20% (± 2.9) and Kentucky bluegrass cover was 19% (± 4.0) in burned plots after the third growing season. Spring and fall treatments had similar native plant cover after three growing seasons. Spring and fall application of 0.33 kg ai ha−1 imazapyr and 0.10 kg ai ha−1 imazapic + 0.16 kg ai ha−1 imazapyr had ≤ 10% smooth brome cover and increased native species cover after three growing seasons. Herbicides were effective at reducing cover of smooth brome and Kentucky bluegrass, and can be incorporated with other management strategies to restore prairie remnants.

Little is known about the impacts and effects of exotic, invasive grasses on wildlife in the Southeast United States. We selected 3 species of exotic grasses common to the Southeast and review the literature on their regional distribution, ecosystem impacts, wildlife impacts, and management. These grasses have the potential to harm indigenous wildlife species, such as northern bobwhite (Colinus virginianus), that need grasslands with a shrub component for nesting, brood-rearing, and loafing. These exotic, invasive grasses are sod-forming in nature, typically forming dense monotypic stands that provide little bare ground and have low plant species and insect diversity. Furthermore, it appears that wildlife do not prefer to consume these plant species. Control is often difficult and usually requires the use of herbicides in combination with mechanical treatment, such as disking, to provide adequate habitat. Attempts should be encouraged to convert these idle grasslands to a mixture of native grasses and forbs to make stands more suitable for wildlife species. We provide suggestions for future research and management needs regarding exotic, invasive grasses and wildlife in the Southeast United States. Ó

Grassland restoration attempts to rehabilitate and/or re-create biologically diverse native plant communities using a variety of management techniques including seeding, burning, grazing, and most recently using herbicides. Herbicides are an important tool for suppressing weed competition for initial seedling growth and removing exotic species in native plant communities. Little information is available on which species of native plants can endure a pre-emergent application of the imidazolinone herbicides. In spring 2006, we initiated a study testing responses of three native grasses and three native forbs to pre-emergent treatments of 0.035 kg ai/ha imazapic, 0.07 kg ai/ha imazapic, and 0.07 kg ai/ha imazapyr. Seedling establishment was monitored at 5 and 14 months after treatment and weed cover was monitored at 2.5, 5 and 14 months after treatment. There were no differences in the number of seedlings found in the untreated plots compared to all the herbicide-treated plots and there were no differences in seedling densities of green needlegrass (Nassella viridula) with the exception of the high imazapic treatment. Showy tick trefoil (Desmodium canadense) and Canada milk vetch (Astragalus crassicarpus) also appear to be able to tolerate applications of all herbicide treatments. There was less weed cover in the herbicide-treated plots when compared to the untreated control plots. This information provides managers options to include these species in initial seeding or restoration projects using these herbicides which may increase diversity and reduce restoration projects cost in the long term.