MANAGEMENT CONSIDERATIONS FOR CONTROLLING SMOOTH BROME ON FESCUE PRAIRIE

Smooth brome (Bromus inermis Leyss.), an introduced perennial grass, i s an aggressive invader of prairie dominated by plains rough fescue (F estuca altaica Trin. subsp. hallii [Vasey] Harms). We (1) compared ric hness and density of plant species in brome and fescue stands that wer e unburned or burned in spring or fall; (2) determined the effects of wick application of a 33% glyphosate solution, applied when smooth bro me was in the boot stage, on the density of brome and native flora in unburned plots and plots burned in spring or fall, and; (3) determined the composition of the seedbank for its potential contribution to nat ural revegetation following the control of smooth brome. Stem densitie s of native species and plains rough fescue were about two- and fivefo ld greater, respectively, in fescue plots than in brome plots. Species richness was generally slightly greater in fescue than in brome plots . Burning had no significant effect on stem density of smooth brome. A t one site, changes in the density of smooth brome were affected by th e interacting effects of burn treatments and glyphosate application, G lyphosate eliminated brome in the spring burn plots and reduced densit ies 76 and 50% (SE +/- 6.4) in the fall burn and unburned plots, respe ctively. At a second site, smooth brome densities were reduced by glyp hosate but not by burn treatments. There was, however, a trend for gre ater reduction of smooth brome with glyphosate application in the spri ng burn (98%) than in the fall burn (40%) and unburned (56%) plots (SE +/- 15.5). Glyphosate reduced the density of native graminoids 91% (S E +/- 10.0), but plains rough fescue and native forbs were not affecte d. Twenty-three species emerged from the seedbank in fescue plots, whe reas twenty emerged from soils collected in brome plots. The total num ber of seedlings emerging from the seedbank was similar in brome and f escue plots, averaging 1794/m(2) and 2078/m(2) (SE +/- 252), respectiv ely. The proportion of seedlings emerging was lower for native gramino ids (33 vs 41%, SE +/- 2) and greater for native forbs (56 vs 48%, SE +/- 3) in brome as compared to fescue plots. Smooth brome seedlings em erged only from soils collected in brome plots, averaging 3/m(2). Thes e studies indicate that excellent control of smooth brome can be achie ved with spring burning followed by wick application of glyphosate; ho wever, native species were also reduced by glyphosate. Additional glyp hosate applications will be required for complete control of smooth br ome. The number of seeds of native species in the soil in smooth brome stands approximates that in stands of plains rough fescue, suggesting that there is an adequate seedbank for natural recovery of vegetation following control of smooth brome.