Chemical Weed Control
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2014 North Carolina Agricultural Chemicals Manual The 2014 North Carolina Agricultural Chemicals Manual is published by the North Carolina Cooperative Extension Service, College of Agriculture and Life Sciences, N.C. State University, Raleigh, N.C. These recommendations apply only to North Carolina. They may not be appropriate for conditions in other states and may not comply with laws and regulations outside North Carolina. These recommendations are current as of November 2013. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your county Cooperative Extension agent. The use of brand names and any mention or listing of commercial products or services in this document does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. VII — CHEMICAL WEED CONTROL 2014 North Carolina Agricultural Chemicals Manual VII — CHEMICAL WEED CONTROL Chemical Weed Control in Field Corn ...................................................................................................... 224 Weed Response to Preemergence Herbicides — Corn ........................................................................... 231 Weed Response to Postemergence Herbicides — Corn ......................................................................... 232 Chemical Weed Control in Cotton ............................................................................................................ 233 Weed Response to Preplant, Preemergence, and Postemergence Overtop Herbicides in Cotton ......... 242 Weed Response to Postemergence Directed Herbicides in Cotton ......................................................... 243 Weed Response to Burndown Herbicides for Conservation Tillage Cotton ............................................. 244 Chemical Weed Control in Peanuts.......................................................................................................... 245 Weed Response to Preplant Incorporated, Preemergence, and At-Cracking Herbicides in Peanuts ..... 250 Weed Response to Postemergence Herbicides in Peanuts .................................................................... 251 Chemical Weed Control in Sorghum ........................................................................................................ 252 Chemical Weed Control in Soybeans ....................................................................................................... 255 Weed Response to Preplant Incorporated and Preemergence Herbicides in Soybeans ....................... 264 Weed Response to Postemergence Herbicides in Soybeans .................................................................. 265 Chemical Weed Control in Sunflowers ..................................................................................................... 266 Chemical Weed Control in Tobacco ......................................................................................................... 267 Weed Response to Herbicides in Tobacco .............................................................................................. 269 Chemical Weed Control in Wheat, Barley, Oats, Rye, and Triticale ........................................................ 270 Weed Response to Herbicides in Small Grains ....................................................................................... 274 Glyphosate Formulations .......................................................................................................................... 275 Herbicide Resistance Management.......................................................................................................... 276 Herbicide Modes of Action for Hay Crops, Pastures, Lawns, and Turf .................................................... 280 Chemical Weed Control in Clary Sage ..................................................................................................... 283 Chemical Weed Control in Small Fruit Crops ........................................................................................... 284 Chemical Weed Control in Tree Fruit Crops ............................................................................................ 290 Chemical Weed Control in Hay Crops and Pastures ............................................................................... 297 Chemical Weed Control in Lawns and Turf .............................................................................................. 303 Chemical Weed Control in Ornamentals .................................................................................................. 318 Chemical Weed Control in Vegetable Crops ............................................................................................ 321 Chemical Weed Control in Forest Stands ................................................................................................ 347 Forest Site Preparation, Stand Conversion, Timber Stand Improvement ................................................ 349 Aquatic Weed Control ............................................................................................................................... 354 Biological Control of Aquatic Weeds with Triploid Grass Carp ................................................................ 356 Chemical Control of Aquatic Plants .......................................................................................................... 357 Pond Dyes ................................................................................................................................................ 361 Chemical Control of Specific Weeds ........................................................................................................ 363 Chemical Control of Woody Plants ........................................................................................................... 366 Total Vegetation Control in Noncropland ................................................................................................. 368 223 Chapter VII — Chemical Weed Control Chemical Weed Control in Field Corn W. J. EVERMAN, Crop Science Department NOTES: A mode of action code has been added to the Herbicide and Formulation column of this table. Use MOA codes for herbicide resistance management. See Table 7-10, Herbicide Resistance Management, for details. Control of witchweed is part of the State/Federal Quarantine Program. Contact the N.C. Department of Agriculture, Plant Industry Division, at 1-800-206-9333. TABLE 7-1A. CHEMICAL WEED CONTROL IN FIELD CORN Amount of Pounds Active Herbicide, Mode of Action Formulation Ingredient Per Code1 and Formulation Per Acre Acre Precautions and Remarks NO-TILL BURNDOWN, Emerged annual weeds, top-kill and suppression of perennials glyphosate, MOA 9 See label 0.38 to 1.13 (lb a.e.) Glyphosate is available as an isopropylamine salt and a potassium salt. Glyphosate formulations and (numerous brands and application rates should be compared on the basis of pounds of glyphosate acid equivalent (a.e.) per gallon formulations) and per acre, respectively. The rate in the preceeding column is expressed as a.e. See TABLE 7-10 for glyphosate rate conversions. Apply before crop emerges. Glyphosate rate depends upon weed species and weed size; see labels for suggested rates. See comments on labels concerning nitrogen as the carrier. Weed control may be decreased when nitrogen or other liquid fertilizers are used as carriers. Apply in 10 to 20 gal of water per acre using flat fan nozzles. For residual grass and broadleaf weed control, glyphosate can be tank mixed with most preemergence corn herbicides and herbicide combinations. See the section on Corn—Preemergence. Refer to specific product labels for application rates, weeds controlled, application directions, and precautions. Adjuvant recommendations vary according to the glyphosate product used. See label of brand used for specific recommendations. May tank mix glyphosate with Harmony SG at 0.45 to 0.9 oz per acre to improve control of curly dock, Carolina geranium, henbit, and wild garlic. Tank mix can be applied anytime prior to corn emergence. See Harmony SG label for details. May tank mix Resolve with glyphosate for improved control of Italian ryegrass and henbit. Glyphosate and the above glyphosate tank mixes will not control field pansy. A tank mix of Gramoxone plus atrazine should be used where field pansy is present. Glyphosate-resistant horseweed (marestail) is now common in eastern North Carolina counties. A tank mix of glyphosate or Gramoxone plus either 1.5 to 2 pt of 2,4-D or 0.5 pt of Clarity is suggested. Apply these tank mixes 7 to 14 days ahead of planting. If horseweed is present at planting time, a tank mix of Gramoxone plus atrazine is suggested. paraquat, MOA 22 0.5 to 1 (lb a.e.) Apply before, during, or after planting but before crop emerges using clean water or clear fertilizer solution (Gramoxone Inteon) 2 SL 2 to 4 pt as the carrier. Apply in a minimum of 10 GPA (20 to 40 preferred) using flat fan nozzles. Add either a (Firestorm) 3 SL 1.33 to 2.67 pt nonionic surfactant at 1 pt per 100 gal or a crop oil concentrate at 1 gal per 100 gal. Use 0.5 to 0.64 lb a.e. (Parazone) 3 SL 1.33 to 2.67 pt on weeds 1 to 3 in., 0.75 lb a.e. on weeds 3 to 6 in.,