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• <br />Cooperative Extension Service <br />Colorado State University <br />Fort Collins, Colorado <br />Photography and color prints courtesy of Adolph Coors Co., Golden, Colo. <br />Eugene Heikes1 <br />Dalmatian Toadflax <br />(Linazia dalmatica) <br />Dalmatlan toadflax Ss a relatively new weed <br />in Colorado; it has been found in several of the <br />mountain counties in the northern part of the <br />State, but is a potential hazard to all of western <br />and part of eastern Colorado. It is mainly a <br />weed on rangeland but can also cause trouble <br />in cultivated areas. Farmers and ranchers <br />ahould become familiar with this weed and <br />eliminate patches before they get well estab- <br />lished. Report any known infestations of this to <br />your county extension agent and by all means <br />prevent it from producing seed. <br />DESCRIPTION: Dalmatian toadilax Ss a nox- <br />ious weed with thick creeping rootstocks. It <br />closely resembles yellow toadflax (Linazia <br />vulgaris) but is a larger plant. The leaves are <br />waxy, heart-shaped, and clasp the stem. Dal- <br />matian toadflax grows from 2 to 5 feet high; it <br />is medium- to shallow-rooted, and is a creep- <br />ing perennial with bright yellow flowers tinged <br />with orange and usually grows in clumps. It is <br />commonly found on sandy or gravelly soils but <br />it will also do well on more fertile soils. The <br />plant is a heavy seed producer and spreads <br />rapidly when competition from other plants is <br />poor. Once established !t can completely dom- <br />inate rangeland and appears to adapt yell to <br />poor range conditions. It is very unpalatable to <br />livestock. <br />CONTROL: Dalmatian toadflax reacts better <br />to intensive cultivation than some of the other <br />ss <br />noxious weeds, One year of intensive summer <br />fallow will usually kill a high percentage of <br />plants. Top growth of this weed is not killed <br />with less than 3 pounds of 2,4-D per acre. <br />2,4,5-T and 2,4,5-TP (silvex) have been re- <br />ported by other states to be superior and will <br />kill a higher percentage of toadflax with one <br />application than 2,4-D, Dense grass competition <br />combined with 2,4-D or other phenoxy herbi- <br />cides will reduce vigor and stands of toadflax. <br />Control measures should include efforts to <br />prevent seed production, including mowing and <br />burning. <br />ERADICATION: Research work done on this <br />weed in Colorado with herbicides has been very <br />limited. Of materials tested, 2,3,6-TBA (Trys- <br />ben 200 or Benzac 1281) or the granular form <br />(Benzabor), or Banvel-D (Dicamba) have shown <br />promise. TBA at 20 pounds per acre (10 gallons <br />of the liquid formulation per acre or 1 1/2 <br />pounds per square rod of the granular formu- <br />lation) or Banvel-D (Dicamba) at 10 pounds per <br />acre (2 1/2 gallons) has killed this weed for 2 <br />years. These herbicides should be applied in <br />early spring or in the fall before normal rain- <br />fall periods. These chemicals are classified as <br />temporary soil sterilants but most grass spe- <br />cies are not seriously injured and grass com- <br />petition will be maintained in treated areas. <br />These herbicides should be used on noncropped <br />land only, <br />1Weed epe<ia11sC, <ooperat lve extension service, Colorado State University. <br />Issued !n furtherance of Cooperative Excenslon Vark in agriculture and home economics, Acts of <br />Hey S and June 70, 1914, in cooperation wich the Uniced Scates Departmenc of Agriculture. Lovell H. <br />Slatts, Director of Extension Service, Colorado Slate University. <br />