Growing-season prescribed fire and herbicide application, but not mowing, is effective in short-term control of the invasive grass Bothriochloa ischaemum on Blackland Prairie and Edwards Plateau, Texas, USA

Published source details Simmons M.T., Windhager S., Power P., Lott J., Lyons R.K. & Schwope C. (2007) Selective and non-selective control of invasive plants: the short-term effects of growing-season prescribed fire, herbicide, and mowing in two Texas prairies. Restoration Ecology, 15, 662-669
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Summary

Native North American grasslands have been degraded by invasive plants. Their control (or eradication) is often hampered by shared characteristics with native plants. There is evidence that fire, herbicide or mowing management, can cause differential responses in native and invasive grassland species. Bothriochloa ischaemum (an introduced warm-season Eurasian grass) is increasing in southern and central North America. In this study, two Bothriochloa invaded grasslands at Blackland Prairie and Edwards Plateau (Texas, southern USA) were subject to various fire, herbicide and mowing regimes to assess effects on this grass and other plants.

The Blackland Prairie site (27 ha pasture) was dominated by B. ischaemum (39% cover) and native silver bluestem B. laguroides (19%). The Edwards Plateau site (10 ha pasture) was dominated by B. ischaemum (55% cover), with native Texas wintergrass Nassella leucotricha (15%) and meadow dropseed Sporobolus compositus (16%).

In 2004, five replicates of seven treatments (control, single and double herbicide application, early- and late growing-season fire, and single and double mowing) applied within 15 x 15 m plots (randomized plot design) were established.

At Blackland Prairie, glyphosate was applied at 2.5 l/ha (0.89 kg glyphosate/ha) on 2 June and (for repeat application) 23 September. At Edwards Plateau, application rate was 3.8-times higher (13.3 l/ha; 3.40 kg glyphosate/ha) applied 30 June and 23 September. Burns were undertaken mid-late August and end of October-early November. Single and repeated mowing (to about 5 cm) was undertaken early to mid-August and 20 October.

In May 2004 and September 2005, species canopy cover was estimated along a line transect within each plot (point intercept method).

Mowing was ineffective in B. ischaemum control, and had no impact on other dominant species one-year after treatment.

Glyphosate significantly reduced B. ischaemum cover at Edwards Plateau (higher application rate) and to a lesser extent by repeated application at Blackland Prairie. At Edwards Plateau, the other two co-dominants grasses also exhibited a negative, but non-significant, response to glyphosate.

Growing-season fire reduced B. ischaemum cover (but the magnitude of response was inconsistent), with co-dominants responding neutrally or positively to fire. Overall, as well as producing best results, burns had lowest implementation costs.

Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://onlinelibrary.wiley.com/doi/10.1111/j.1526-100X.2007.00278.x/full