The invasive annual grass downy brome (Bromus tectorum L.) is a critical threat to the semiarid shrublands that characterize western North America. More abundant fine fuel after invasion typically increases fire frequency in plant communities adapted to relatively infrequent burning, reducing the likelihood of native plant persistence. Currently, imazapic is most often used to manage B. tectorum, but reinvasion from the seedbank after treatment is common. Indaziflam is a newer herbicide recently labeled for use in rangelands grazed by livestock, and many research trials have demonstrated its ability to deplete invasive annual grass seedbanks. We evaluated the effectiveness of indaziflam and imazapic for reducing B. tectorum density and cover over a period of approximately 5 yr (57 mo after treatment [MAT]) at two invaded sagebrush-grassland sites near Pinedale, WY. Treatments included three different indaziflam rates (51, 73, and 102 g ai ha−1) and one imazapic rate (123 g ai ha−1), and these treatments were reapplied to half of each plot at 45 MAT to evaluate the effects of two sequential applications. We also measured perennial grass cover, because positive perennial grass responses were observed after release from B. tectorum competition in other studies, and perennial grasses may provide resistance to B. tectorum reinvasion. Intermediate and high indaziflam rates (73 and 102 g ha−1, respectively) reduced B. tectorum cover and density at 45 MAT, and perennial grass cover responded positively to some treatments, mostly early in the study (≤33 MAT). Imazapic reduced B. tectorum initially, but did not affect density or cover at either site beyond 21 MAT. Reapplication did not substantially improve B. tectorum control at 57 MAT in plots treated with intermediate and high indaziflam rates, suggesting that long-term control with a single indaziflam treatment may be possible in some cases.

侵入性的一年生草丛羽绒雀 ( Bromus tectorum L.) 是对北美西部半干旱灌木地的严重威胁。入侵后更丰富的精细燃料通常会增加适应相对不频繁燃烧的植物群落的火灾频率，从而降低本地植物持久存在的可能性。目前，imazapic 最常用于管理B. tectorum，但处理后从种子库再次入侵很常见。Indaziflam 是一种较新的除草剂，最近被标记用于牲畜放牧的牧场，许多研究试验已经证明它能够耗尽侵入性的一年生草种子库。我们评估了吲达西兰和灭草定对减少B. tectorum的有效性在怀俄明州派内代尔附近的两个被入侵的山艾树草原地点，大约 5 年（处理后 57 个月 [MAT]）的密度和覆盖。处理包括三种不同的吲达齐弗兰比率（51、73 和 102 g ai ha -1）和一种 imazapic 比率（123 g ai ha -1），这些处理在 45 MAT 时重新应用于每个地块的一半以评估两个连续的应用程序。我们还测量了多年生草覆盖率，因为在其他研究中从B. tectorum竞争释放后观察到多年生草的积极反应，并且多年生草可能对B. tectorum再入侵提供抵抗力。中度和高吲达唑仑用量（分别为 73 和 102 g ha -1）降低B. 45 MAT 的顶盖覆盖和密度以及多年生草覆盖对某些处理有积极反应，主要是在研究早期（≤33 MAT）。Imazapic 最初减少了B. tectorum，但不影响超过 21 MAT 的任一地点的密度或覆盖。在用中等和高吲哒唑菌处理的地块中，重新施用并没有显着改善57 MAT 的B. tectorum控制，这表明在某些情况下，用单一的吲哒唑菌治疗进行长期控制是可能的。