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Table 1. Herbicide options for controlling Russian knapweed. <br />All label directions and precautions must be followed. <br />Do not I1SA hPrhiriri*AC that will rinmana riacirnhla cnariac <br />Herbicide Rate Notes Reference <br /> Apply in the fall following the first heavy frost. <br /> . 1 pint to 1 quart/ Follow application with cultivation to bury & decom- <br /> acre if broadcast- post allelopathic leaves, and seeding w/ picloram- <br />Picloram, e.g., <br />® sprayed tolerant plant species (e.g., grasses). Application 1-4 <br />Tordon <br />• 2 quarts/acre if for 2 consecutive years may be necessary. Piclo- <br /> <br />spot-sprayed ram is a restricted-use herbicide. Will kill or severe- <br /> ly injure most other broadleaf species via soil or <br /> foliage. <br />Picloram + 1-1.5 pints Tordon + Apply Tordon at any time during active growth. <br />2,4-D 1 quart 2,4-D/acre Application for 2 consecutive years may be neces- 1 <br /> sa . <br />Metsulfuron, <br />e. q., Escort 0.75-1 oz./acre Apply with non-ionic surfactant. 1 <br />Metsulfuron + 1 oz. Escort + 1-2 Apply with non-ionic surfactant. Optimum applica- <br />2,4-D pints 2,4-D/acre tion is when R. knapweed is in bud to early bloom 2 <br /> or in fall following frost. <br />Clopyralid Mid-October application (specific to N. Dakota) or <br />, <br />e.g., Stinger, <br />8 oz./acre late bolting to early bud stage . Annual applica- <br />2 <br />4 <br />Transline tion may be necessary for several years. Will injure , <br /> legumes (e.g. , clover). <br />Clopyralid + 2-4 quarts/acre Apply when weeds are young and actively growing, <br />2,4-D, e.g., (0.38 pounds clopy- or after the growing season. Competitive desira- 2 <br />3 <br />Curtail ralid plus 2 pounds ble species should not be planted for one month , <br /> 2,4-D following application. <br /> 4 pints/acre (0.38 <br />Redeem pound clopyralid <br />plus 1.1 pounds tric- Mid-October application (specific to N. Dakota) 2 <br /> lo r <br />Imazapie 12 oz./acre Effective for the treatment of mature Russian 3 <br /> kna weed. <br /> 2-4 lb. acid equiva- Apply when plants are in early bud stage. Annual <br />Dicamba lent/acre application may be necessary for several years. 4 <br /> Will kill all other broadleaf plants. <br />GVVJ <br />2 Lym, 2004 <br />3 Graham and Johnson, 2004 <br />a CDFA <br />3.4 BIOLOGICAL CONTROL <br />The gall nematode (Subanguina picridis), destructive in its larval and adult stages, forms galls <br />on the stems, leaves and root crowns Russian knapweed. Although the nematode has not been <br />known to kill Russian knapweed, it does reduce the vigor of the weed. This is the first nema- <br />tode species to be released in North America for biological weed control. It has not been found <br />to readily spread long distances without assistance. There are currently no insects approved for <br />introduction into the United States for control of Russian knapweed. <br />6