Rangeland managers need tools to control invasive annual grasses, particularly following wildfire. We assessed responses of native and invasive/exotic grasses to the MB906 soil amendment containing live cultures of a purportedly weed-suppressive strain of the bacterium Pseudomonas fluorescens (“WSB”). MB906 was applied alone and in combination with the pre-emergent herbicide imazapic on >3000 ha across three sagebrush-steppe landscapes burned several months prior. Replicate plots of each treatment type were established and plant cover was measured in the following three years. Cover of invasive-annual grasses (“IAG”) was not responsive to MB906 when all IAG species were considered (“IAG-All”). However, MB906 led to a 54% reduction in the IAG's that were previously reported to be controlled by WSB (“IAG-Target”) in the second year following application (IAG-Target = cheatgrass, Bromus tectorum and medusahead, Taeniatherum caput-medusae; IAG-All also includes Vulpia myuros and Bromus arvensis). MB906 reduced the effectiveness of co-applied imazapic: Imazapic alone reduced IAG-All by 83% and 68% in years 1 and 2, respectively, while imazapic+MB906 reduced IAG-All by 48% and 38% in years 1 and 2, respectively, across all landscapes, and a similar response pattern was observed for IAG-Target. Perennial grass cover was unaffected by the treatments except where it increased 4-fold in response to imazapic applied at a high rate (0.140 kg a.i. ha⁻¹) in one of the landscapes. Tank mixing MB906 and herbicide may have lessened the biological activity of the herbicide by altering the pH or mineral content of the spray solution or by direct metabolism of the herbicide by the bacteria. These results do not provide strong support for MB906 as a tool for annual grass control, though they suggest further investigation may be warranted.

牧场管理员需要工具来控制一年生入侵草，尤其是野火之后。我们评估了原生和入侵/外来草对MB906土壤改良剂的反应，MB906土壤改良剂包含荧光假单胞菌的杂草抑制菌株的活培养物。（以下简称“ WSB”）。MB906单独施用，并与发芽前的除草剂灭草灵联合使用，在三个月前燃烧的三个鼠尾草草原景观中，占地> 3000公顷。建立每种处理类型的重复样地，并在接下来的三年中测量植物的覆盖率。当考虑了所有IAG物种（“ IAG-All”）时，入侵性一年生禾草（“ IAG”）的覆盖率对MB906没有响应。但是，MB906导致IAG降低了54％，之前据报道，IAG在应用后第二年（“ IAG-Target =白茅草，Bromus tectorum和medusahead，Taeniatherum caput-medusae）由WSB控制; IAG-所有还包括鼠茅和田雀麦）。MB906降低了联合应用伊马沙比的有效性：仅Imazapic在第1年和第2年就分别降低了IAG-All的83％和68％，而在Izap + MB906在第1和第2年中分别降低了IAG-All的48％和38％。分别在所有景观上，对IAG-Target观察到了相似的响应模式。多年生草皮不受该处理的影响，除非对伊马扎比以高用量（0.140 kg ai ha ^-1施用）增加四倍）在其中一种景观中。罐混MB906和除草剂可能通过改变喷雾溶液的pH或矿物质含量或除草剂被细菌直接代谢而降低了除草剂的生物活性。这些结果并没有为MB906作为一年生草地控制的工具提供有力支持，尽管它们暗示可能需要进一步调查。