Invasive plants or noxious weeds are plants that have been introduced into an environment in which they did not evolve and thus usually have no natural enemies to limit their reproduction and spreading.  The problem with non-native invasive plants is the increasing rate of human distribution of flora and fauna around the world which has caused the displacement of native species, increased fire frequency (especially in the Great Basin), and required millions of dollars to be spent annually on invasive species control.  Although natural invasions of plants and animals have occurred in the past, none have compared in scale to the present human-induced migration of species.  To become a problem, invasive, competitive plants must be introduced into an area.  They must then establish themselves, reproduce and disperse.  Control or management is easiest and least expensive during the first two stages and difficult and very expensive during the last.  The key to control is to identify potential weed infestations at very early stages, as well as educate the public about how destructive these plants can be.   These large areas of wildlands are exposed to varying amounts of weed infestation depending upon the level of disturbance and the availability of weed seed.  In the ESWMA, approximately  40,000 acres of land are currently infested with non-native invasive plants.  To date, the various cooperators in the ESWMA have spent over $3 million on weed management activities  (click here for the weed location form)  - PDF file is 418 kilobytes (Adobe Acrobat Reader is needed to view or print - you can download Adobe Acrobat Reader for free from the company, if you do not have it).  Send completed forms to the Inyo/Mono County Agricultural Commissioner´s Office at 207 West South Street, Bishop, CA 93514, or call (760) 873-7860.