Physical removal of alligator weed is possible, but not usually 100% successful in eradicating the weed because the plant is able to re-grow and propagate from stem fragments alone. There are currently no biological control methods of eradication rather than goats which can keep the plant under control by feeding on the weed. Chemical control has been found to be the most successful when containing fluridone or imazapyr. Other chemical treatments have been found slightly less successful, but still effective when containing: 2,4-D, glyphosate, triclopyr, and imazamox. Systematic herbicides such as Navigate and Weedar 64 are successful chemical treatments as well.
U.S. Habitat: Alligator weed can grow in a variety of habitats from dry to immersed in water, but the preferred habitat is aquatic. In the United States alligator weed is most often found growing along the surface of streams and ponds at the shores edge.
Barreto, R., R. Charudattan, A. Pomella, and R. Hanada. 2000. Biological control of neotropical aquatic weeds with fungi. Crop Protection 19: 697-703.
Holcomb, G. E. 1978. Alternaria alternantherae from alligatotorweed is also pathogenic on ornamental Amaranthaceae species. Phytopathology 68: 265-266.
U.S. Present: Alligator weed is found in the southwest United States from San Joaquin Valley south to Los Angeles and across the south and east portions of the continent south to Central America.
Alligator weed is most commonly found spread across the surface of a body of water described in a sprawling fashion. It can be found in terrestrial areas around gardens or in between rows of crops with sufficient moisture present. Stems are pink and hollow and can reach lengths of 1 m with opposite narrow elliptical leaves. Flowers are reduced and white in color, have thin petals, and are on stems that extend 4-5 inches away from the plant.
Alligator weed is able to spread and reproduce rapidly through stems or leaf cuttings making it difficult to eradicate in areas once established because it can grow from small portions of the plant left behind. Alligator weed propagates most commonly from stolons vegatatively with each individual node capable of propagating allowing for rapid spread and propagation of the plant.
Alligator weed is non-native to North America and should not be spread. It is an obligate wetland plant that can be found in waste places in ponds, streams, and along some rivers.
USDA, NRCS. 2018. The PLANTS Database (http://plants.usda.gov, 28 March 2018). National Plant Data Team, Greensboro, NC 27401-4901 USA.
Illustration courtesy of University of Florida/IFAS Center for Aquatic and Invasive Plants. Used with permission.
This is a non-native plant that should not be grown as it is invasive and illegal to possess or transport this species in Texas. Please report sightings to the Texas Parks and Wildlife Department at (512) 389-4800.