2013-11-27_PERMIT FILE - C1981018A (3)

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• In this example we would attempt to preserve the existing vegetation while controlling the cheatgrass to the best of our ability. Cheatgrass is a winter annual or annual. Post-emergent treatment with glyphosate (Roundup) or imazapic (Plateau or Journey) would be advisable. We delay reseeding and spray just prior to freeze up. Cheatgrass is typically the last plant to go dormant and first to break dormancy. Delayed spraying allows the maximum emergence of cheatgrass seedlings while allowing other desirable species to go dormant reducing their susceptibility to the herbicide. Reseeding occurs late in the fall to early winter following the plant- back intervals on the herbicide product label. Under this scenario one can expect additional sprouting of cheatgrass in the spring but the reduction in cheatgrass stand density will hopefully be sufficient to aid the establishment of the desired species. Use of imazapic on BLM lands was finally initially allowed through BLM's Programmatic Environmental Impact Statement (PETS) addressing herbicide use on the lands they manage. BLM approval of this herbicide provides additional options under this scenario not previously available. Imazapic has both preemergent and postemergent activity which is capable of controlling cheatgrass for several years. Many of the key species found in BME's seed mix are known to be tolerant of imazapic. This tolerance is also variable between preemergent and postemergent applications. Further evaluation and experience with its effects on the vegetation and seedling establishment will be needed as some of the desired species are not listed. • Scenario example #2: Avery dense stand of Russian thistle seedlings (7 to 2 inches in height) are observed on a reclaimed site in its second year of growth. Desirable plants include the normal grasses plus alfalfa, milkvetch, and several shrub species. Dense stands of Russian thistle will out-compete the relatively young perennial seedlings for moisture and nutrients. While some of the more aggressive perennial grasses would be expected to persist with this competition the stand diversity and vigor would most likely suffer. The trick to using herbicides in this situation is to preserve the desirable forbs and shrubs while controlling the Russian thistle. A minimal dose of 2,4-D can be used in this situation. The key is to have the application rate sufficient to control the Russian thistle but not adversely impact the desirable forbs and shrubs. Seedlings are generally most susceptible to herbicides when they are very young. Thus timing is critical and waiting until the thistle seedlings are even one or two inches taller may cause unsatisfactory results at very light application rates. Similar strategies may be available for other weeds such as blue or tumble mustard. However, consideration should then be given to using Telar or Escort instead of 2,4-D due to the known sensitivity of mustards to these products. • Technical Revision #65 (4/2008) V-70