Skip to main content
U.S. flag

An official website of the United States government

Herbicides sprayed to inhibit exotic annual grass germination and establishment can have unintended effects, including the release of secondary invaders or damage to native plant species.

USGS researchers investigated how exotic and native plant functional groups, species diversity, and a cheatgrass pathogen (Ustilago bullata) responded to treatment targeting exotic annual grasses. The area was burned in 2016 and then treated with the pre-emergent herbicide imazapic and weed-suppressive bacteria (Pseudomonas fluorescens, strain MB906). Exotic annual grass cover and species richness were initially suppressed with treatment but increased to levels similar to untreated plots by the third year. Spraying to treat a single plant functional group did not release native perennials sufficiently to counteract the simultaneous release of secondary invaders; the treatment increased exotic perennial forb cover and cover of the invasive biennial bulbous bluegrass. Authors suggest planting or seeding may also be needed to achieve management goals in these diversely invaded communities.

Lazarus, B.E., Germino, M.J., 2021, A chemical and bio-herbicide mixture increases exotic invaders, both targeted and non-targeted, across a diversely invaded landscape: Applied Vegetation Science, v. 24, no. 2, e12574,

Get Our News

These items are in the RSS feed format (Really Simple Syndication) based on categories such as topics, locations, and more. You can install and RSS reader browser extension, software, or use a third-party service to receive immediate news updates depending on the feed that you have added. If you click the feed links below, they may look strange because they are simply XML code. An RSS reader can easily read this code and push out a notification to you when something new is posted to our site.