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Weeds and the

Many troublesome weeds in the United States are natives of other countries. These weeds were brought to North America accidentally or deliberately and arrived without the living organisms that infect or feed upon them. Without their natural enemies, these exotic plant species outcompete native plant species and displace native wildlife.

Facts About Weeds


Weeds muscle out crops and other desirable plants by competing for water, nutrients, sunlight and space. One example: A single mature tamarisk plant can consume 200-300 gallons of water a day.


Many invasive weeds are nonnative plants first introduced in North America as ornamentals. Examples include tamarisk (Tamarix sp.) Japanese barberry (Berberis thunbergii) and Scotch broom (Cytisus scoparius).


Nearly 250 weed species have developed resistance to the herbicides used to control them.


Weeds can promote flooding during hurricanes by jamming control pumps and blocking water flow.


Weeds such as cheatgrass (Bromus tectorum) or red brome (B. rubens) can pave the way for rampant wildfires.


Researchers at the University of Guelph confirm the significant impact of unchecked weeds on crops, including yield reductions of more than 50% for dried bean and corn corps.