ABSTRACT
Bitterweed occurs from southwestern Kansas to northern Mexico and southeastern California. Bitterweed is an invader plant on most range sites of the Edwards Plateau. It is found in greatest abundance in lake beds, draws, along roadsides, around pens and watering places, and in other areas where the grass stands have been thinned because of drought, overgrazing, or soil disturbance. Bitterweed can be controlled with 2,4-D [(2,4-dichlorophenoxy) acetic acid], picloram (4-amino-3,5,6-trichloropicolinic acid), and other herbicides. Bitterweed poisoning problems in sheep production are most commonly handled through alterations of grazing and livestock management practices. Principal cost increases are for additional feed and labor associated with observing, penning, and drylot feeding the ewes showing symptoms of bitterweed poisoning. Despite the lack of precision regarding the magnitude of its economic impact, it is safe to assume that bitterweed is a serious problem in the western Edwards Plateau, and there is a need to continue to search for economical means of reducing its detrimental impacts.
