Controlling annuals with Plateau in a wildland-urban interface fuelbreak. Smith, Edwin^*,1, Davison, Jason^*,1, ¹ University of Nevada Cooperative Extension, Minden, Nv, USA

ABSTRACT- Removing wildland shrubs to create fuelbreaks along the wildland-urban interface in the Great Basin often results in the invasion of annual weedy species. These annuals are easily ignited when dry and can serve as a wick to heavier fuels, thus partially negating the value of the fuelbreak. Annuals can also thwart the establishment of more fire resistant species seeded into fuelbreaks. The University of Nevada Cooperative Extension, in cooperation with several other entities, conducted an evaluation of the effectiveness of the herbicide Plateau in controlling cheatgrass Bromus tectorum, fillaree Erodium cicutarium, and tumble mustard Sisymbrium altissimum in a Carson City, Nevada fuelbreak in 2004. Sixteen, 560 s.f. plots were established in a big sagebrush and bitterbrush vegetation type (i.e., NRCS Range Site 26-10). Three treatments and a control were replicated four times. The treatments were: 1) Plateau sprayed at 6 oz./acre, not seeded with fire resistant species; 2) Plateau sprayed at 6 oz/acre, seeded with fire resistant species; and 3) seeded with fire resistant species, but not sprayed with Plateau. The plots sprayed with Plateau had significantly less (P<.05) production of cheatgrass, fillaree, and tumble mustard than the unsprayed plots. Furthermore, observations suggest that native, perennial species were unaffected by the herbicide. There was very poor establishment of seeded fire resistant species regardless of the treatment, which was attributed to precipitation 26% of normal. The results suggest that Plateau can be an effective tool in controlling annual species in Great Basin fuelbreaks.

KEY WORDS: herbicide, fuelbreak, Plateau, annuals