Show A drawing showing plants aris ing from underground rootstocks B head consisting consist mg of numerous flowers C seed in face view D seed inside in side view E arm F bract of head description russian knapweed is one of utah s most serious noxious weeds it is perennial and reproduces by seed and underground rootstocks the stems grow two or three feet tall and are grayish green this weed is rather late in maturing its purple flowers appearing usually in june the seed is whitish whitis litan tan oblong flattened and about 24 4 inch long portions of the root near the surface of the soil have a characteristic grayish black bark or covering occurrence russian knapweed is said to have been introduced from europe with alfalfa seed it is now common in most of the western states patches can be found in most of the counties of utah and it is considered a ser ious problem in much of the eastern part of the state this weed has wide adaptation and occurs in cultivated felds as well as in waste places it seems to prefer well drained land control russian knapweed is one of the most difficult weeds to control persistence is therefore necessary for success three years of clean cultivation have given almost corn com control the few remaining 1 plants can be cleaned up by spot 1 treatment with chemicals in the crop heavy rates of 2 4 D are re quiren to even bum burn down the top growth of russian knapweed rates often damage corn and so a program of and chemi cheim cals is not practical where plants have been weakened clean cultivation or spraying 24 2 4 D for two years establishing a good stand of pasture has held it in check and seems to have reduced the stand if this is used clipping should be done when necessary to keep the weed from going to seed in treating a solid stand where there is no crop two pounds per acre of any one of these three chem icalas 2 4 D ester 2 4 D amme or 2 4 5 T applied applied each year for four years has given an average of aa 9 percent kill in colorado in waste places such as ditch banks fence lines imes or even small spots in crop land the use of a soil sten lant is probably the best and most sure control measure in colorado applying any one of these C M U at the rate of 40 pounds per acre a chlorate at 1200 pounds per acre or amme amine 2 4 D at the rate of 80 pounds per acre gave ex cellena kills in utah either polly bore chlorate at eight pounds per acre or atla cide at six pounds per acre gave excellent control C ea 6 F A RUSSIAN KNAPWEED drawing and pa t ol 01 descar pt on taken f om utah culau al elpe ament S at on circular |