Weed Identification and Control

Identification and Control

3rd Annual Aquatic Nuisance Species Workshop Presntations

Tamarisk Symposia (1997, 2001, 2003, 2005, 2007 & 2009 Symposia)

The Mesa County Division of Pest Management Home Page
- includes the noxious weeds of Mesa County Colorado
and their control


Identification and Control
Glyphosate and 2,4-D
Best Management Practices for Noxious Weeds of Mesa County
General rules for management practices for noxious weeds of Mesa County. Control recommendations for species on the Mesa County Noxious Weed List and Noxious Weed Biology Table.
Information provided by Jude Sirota, Mesa County Horticulture Pest & Weed Inspector.

Gray Rabbitbrush Control Following Applications of Redeem R&P and Crossbow Herbicides - [Chrysothamnus nauseosus (Pallas) Britt.]
Gray rabbitbrush, Chrysothamnus nauseosus (Pallas) Britt., is a strongly scented perennial plant that has many branches. The stems are silky or white woolly covered and range in height from 2 to 4 feet. The flowers are in large clusters at the tips of the stem and yellow in color.
Information provided by A. Wayne Cooley, Area Extension Agent (Area Director & Soil and Crop Science).
Canada Thistle Control Following Applications of Curtail and Redeem R&P Herbicides - [Cirsium arvense (L.) Scop.]
Canada thistle, Cirsium arvense (L.) Scop., is an aggressive creeping perennial, that once established, becomes very competitive in irrigated pastures and mountain meadows. Canada thistle is also on the state of Colorado and Tri River Area counties noxious weed list.
Information provided by A. Wayne Cooley, Area Extension Agent (Area Director & Soil and Crop Science).
Cuscuta and Grammica species - Dodder
Dodder is a twining yellow or orange plant that parasitizes various kinds of wild and cultivated plants. A photograph of this parasite, discussion and control are provided.
Knapweed - [Acroptilon repens (synonym = Centaurea repens)]
Russian knapweed, Acroptilon repens, is a creeping perennial weed native to Eurasia. It spreads by underground roots that may go to a depth of 8 feet or more and it puts out a chemical that inhibits other species from growing near it (allelopathy).

Information provided by Jude Sirota, Mesa County Horticulture Pest & Weed Inspector.

Leafy Spurge Control Following Herbicide Applications in the Tri River Area
Leafy spurge is native to Eurasia and was brought into the United States as a seed impurity around 1827. Leafy spurge seems to be a serious problem only in North America where it infests almost 2.5 million acres. The greatest infestation is primarily in southern Canada and the north central United States. Leafy spurge is found in several areas of Colorado and has become more wide spread in the Tri River Area in the past few years.
Information provided by A. Wayne Cooley, Area Extension Agent (Area Director & Soil and Crop Science).
Managing Field Bindweed with the Bindweed Mite - Aceria malherbae
The bindweed mite, Aceria malherbae, is a microscopic mite imported from southern Europe as a biological control agent for field bindweed. The bindweed mite feeds only on field bindweed and closely related wild morning glories.

Russian Knapweed: Control Following Applications of Curtail and Redeem R&P Herbicides - [Acroptilon repens (synonym = Centaurea repens)]

Russian knapweed, Centaur repens L., is a deep rooted creeping perennial plant that was first introduced into North America in about 1898. Russian knapweed grows in a variety of soil types and is not associated with any particular soil. Much of the initial invasion of this plant has been traced to contaminated alfalfa seed that was imported from Russia in the 1920's. More recent spread of Russian knapweed seed can be attributed to several different means including motorized vehicles, contaminated gravel for road surfacing, irrigation water, farm equipment, as well as humans, birds, and mammals.

Information provided by A. Wayne Cooley, Area Extension Agent (Area Director & Soil and Crop Science).


Sweet Corn - Band and Broadcast Applied Herbicides in the Tri River Area
Herbicide weed control is one component of production agriculture. Available herbicides should be evaluated periodically to determine crop tolerance and the best product for the weed species present. The population of weed species can change over time, especially if the same product is used year after year. The more available herbicides we have to choose from can, in some cases, provide more consistent weed control and/or allow us more flexibility in our crop rotation.

Information provided by A. Wayne Cooley, Area Extension Agent (Area Director & Soil and Crop Science).

 


white top Cardaria draba Photos by Dr. Curtis E. Swift
Whitetop (Hoary Cress) Cardaria draba
Whitetop is a deep rooted creeping perennial mustard plant. It is very aggressive and will eventually crowd out desirable vegetation if not controlled.
Information provided by A. Wayne Cooley, Area Extension Agent (Area Director & Soil and Crop Science).

Yellow Starthistle - Centaurea solstitialis L.
Yellow starthistle, Centaurea solstitialis L., is a plant of Old World origin that is believed to have arrived in California in the mid-1800's as a contaminant in alfalfa. It is a member of the sunflower family (Asteraceae) and belongs to the thistle tribe (Cynareae). Since its introduction, yellow starthistle has spread steadily and was estimated to inhabit about 8 million acres in California by 1985. In 1999 it was estimated that California had 22 million acres of yellow starthistle.

Information provided by A. Wayne Cooley, Area Extension Agent (Area Director & Soil and Crop Science).


Tamarisk - (Tamarix spp.)

Tamarisk (Tamarix spp.) is native to central Asia. In the late 1800s, eight tamarisk species were brought to the United States for erosion control and to be used as ornamentals, windbreaks and shade trees. In Western Colorado tamarisk has no natural enemies such as insects or diseases to keep its population in check. This has allowed it to spread unchecked along western waterways.

Western Colorado Tamarisk Symposia

Webmaster
Dr. Curtis E. Swift, Area Extension Agent, Horticulture
Colorado State Cooperative Extension
2775 US Hwy 50, Grand Junction, CO. 81503
voice: 970-244-1840
fax: 970-244-1700