This article is an overview of label changes and recently registered weed control products for use in field crops. Label changes and recently registered products are presented alphabetically by the company that manufactures or distributes the herbicide. Information includes the properties and intended uses of these products. Further information on efficacy against certain weed species can be found in the 2003 Illinois Agricultural Pest Management Handbook, the new 23rd edition of the Illinois Agronomy Handbook, and the 2002 University of Illinois Annual Weed Control Research Report.
Distinct 70WDG (active ingredients diflufenzopyr and dicamba). A label change has been made in the rotation restriction for Distinct. A 30-day rotation restriction is required before planting any crop, with the exception of corn. Corn can be replanted 7 days or more after application. Additionally, a registration for popcorn has been received. Rescue applications of Distinct can now be applied with drop nozzles to corn between 24 and 36 inches tall.
Extreme 2.17L (active ingredients imazethapyr and glyphosate). BASF has received a supplemental label for Extreme applications in the fall to control existing vegetation and to provide residual control of winter annual and early spring emerging weeds. Soybean must be planted in the spring after fall Extreme applications. Fall applications of Extreme should be made after harvest and before ground freeze at 3 pints per acre with a nonionic surfactant and nitrogen source.
G-Max Lite 5L (active ingredients dimethenamid-P and atrazine). G-Max Lite is a recently registered premixture containing 2.25 pounds of active ingredient of dimethenamid-P (Outlook) and 2.75 pounds of active ingredient of atrazine. G-Max Lite is a selective preemergence herbicide that controls annual grasses, some annual broadleaf weeds, and sedges in field corn, seed corn, sweet corn, popcorn, and grain sorghum. G-Max Lite is similar to Guardsman Max, with the exception of containing less atrazine. G-Max Lite may be applied up to 45 days before planting (EPP), preplant incorporated (PPI), preemergence (PRE), and early postemergence (EPOS) to corn up to12 inches in height. Split applications are recommended if G-Max Lite is applied more than 30 days EPP. Application rates range from 2.5 to 3.5 pints per acre, depending on soil texture and soil organic matter content. A typical use rate of 3.0 pints per acre of G-Max Lite is equivalent to applying 18 fluid ounces of Outlook and 1.0 pound of active ingredient of atrazine.
Prowl 3.3EC (active ingredient pendimethalin). The fall-applied label for Prowl before soybean planting has been extended to cover all of Illinois. Prowl may be surface-applied or incorporated in the fall from October 1 to December 31, or until ground freeze. Fall applications of Prowl will not provide season-long weed control.
Raptor 1S (active ingredient imazamox). Raptor, an acetolactate synthase (ALS)-inhibiting herbicide, has recently received registration for use in alfalfa. Raptor should be applied early postemergence before annual broadleaf and grass weeds exceed 3 inches in height. Use rates range between 4 and 6 fluid ounces per acre for seedling or established alfalfa grown for forage, hay, or seed. There should be at least 20 days between Raptor application and cutting or feeding alfalfa for forage or hay, and an interval of 70 days between application and harvest of alfalfa seed used for food or feed. Postemergence applications require the addition of an adjuvant (nonionic surfactant, crop oil concentrate [COC], or methylated seed oil) and a nitrogen source.
Scepter 70DG (active ingredient imazaquin). A supplemental label has been granted to BASF for fall applications of Scepter before soybean planting. Fall applications of Scepter should be made after harvest and before ground freeze to provide residual control of winter annual and early emerging summer annual weeds. The use rate is 2.8 ounces per acre, and do not make more than one application per year.
Option 35WDG (active ingredient foramsulfuron). Option is the only herbicide registered in 2002 that contains a new active ingredient. Option is a sulfonylurea herbicide and is labeled for postemergence use in field corn. Use rates range from 1.5 to 1.75 ounces per acre. Broadcast applications may be made when corn is between 0 to 16 inches in height or through the V5 growth stage, whichever is more restrictive. Drop nozzles must be used when corn is between 16 and 36 inches in height. Applications of Option must include a methylated seed oil and a nitrogen fertilizer. The use of nonionic surfactants or COCs results in unacceptable weed control. Do not make more than two applications or apply more than 3.5 ounces of Option per acre per year.
Option has good activity on several grass and broadleaf weed species. Grasses that Option controls include foxtails, fall panicum, barnyardgrass, shattercane, johnsongrass, quackgrass, and wirestem muhly. Some of the broadleaf weeds that Option controls are common lambsquarters, pigweeds, velvetleaf, common ragweed, and eastern black nightshade. Because Option is an ALS inhibitor, it does not provide satisfactory control of ALS-resistant weed biotypes. Tank mixtures with herbicides having other modes of action will be needed to control these species. Labeled tank-mix partners include atrazine, Beacon, dicamba, Distinct, Exceed, Harness, Hornet WDG, Marksman, NorthStar, Prowl, Spirit, Surpass, TopNotch, and Tough. Precautions that should be observed include certain corn hybrids that are sensitive to Option, so consult seed company hybrid sensitivity charts; do not apply Option in the same season if Counter, Dyfonate, or Thimet was used; do not make foliar applications of an organophosphate insecticide within 7 days of an Option application; replant intervals for Option are 7 days for corn, 14 days for soybean, and 60 days for all other crops; the preharvest interval for Option is 70 days for corn grain and 45 days for corn forage.
Dow AgroSciences LLC
Warrant 5.4L (active ingredient glyphosate). Registration of Warrant is expected the third quarter of 2003. Warrant is a higher load glyphosate formulation that contains a surfactant. Warrant is formulated as the isopro-pylamine salt of glyphosate that contains 5.4 pounds of active ingredient per gallon (4 pounds of acid equivalent per gallon). The 24-fluid-ounce rate of Warrant is equivalent to the 32-fluid-ounce rate of a glyphosate formulation with 4 pounds of active ingredient per gallon (3 pounds of acid equivalent per gallon; i.e., Glyphomax Plus).
Keystone 5.25SE (active ingredients acetochlor and atrazine). Keystone is a recently registered premixture containing 3.0 pounds of active ingredient of acetochlor (Surpass) and 2.25 pounds of active ingredient of atrazine. Keystone is formulated as a suspo-emulsion and is used for selective preemergence control of annual grasses, some annual broadleaf weeds, and sedges in field corn, production seed corn, silage corn, and popcorn. Keystone may be applied up to 30 days before planting (EPP), PPI, PRE, and EPOS to corn up to 11 inches in height. Application rates range from 2.2 to 3.4 quarts per acre depending on soil texture and soil organic matter content. A typical use rate of 2.65 quarts per acre of Keystone is equivalent to applying 2.5 pints of Surpass and 1.5 pounds of active ingredient of atrazine per acre.
Keystone LA 5.5SE (active ingredients acetochlor and atrazine). Similar to Keystone, Keystone LA is a premixture of acetochlor and atrazine. However, this formulation has "less atrazine," designed for use in restricted or lower atrazine rate areas. Keystone LA contains 4.0 pounds of active ingredient per gallon of acetochlor and 1.5 pounds of active ingredient of atrazine. The typical use rates of Keystone LA range between 1.8 and 2.2 quarts per acre.
DuPont Agricultural Products
Cinch 7.64EC (active ingredient S- metolachlor), Cinch ATZ 5.5L (active ingredients S-metolachlor and atrazine), and Cinch ATZ Lite 6L (active ingredients S-metolachlor and atrazine) are new herbicides being marketed by DuPont Agricultural Products. The Cinch herbicides are equivalent formulations to Syngenta's Dual II Magnum, Bicep II Magnum, and Bicep Lite II Magnum. These products will replace the discontinued herbicide Leadoff.
Cimarron 60DF (active ingredient metsulfuron). Cimarron is registered for use in pastures, rangelands, and Conservation Reserve Program (CRP) acres. Cimarron is used at 0.1 to 1.0 ounce per acre to control broadleaf weeds. Apply Cimarron in the spring or early summer when weeds are less than 4 inches in height and are actively growing. Cimarron contains the same active ingredient as Ally, and the Cimarron label has many of the same precautionary statements as the Ally label.
Steadfast 75WDG (active ingredients nicosulfuron and rimsulfuron). The maximum corn height for Steadfast applications has been increased to 20-inch-tall corn or corn exhibiting six leaf collars (V6), whichever is more restrictive.
Aim EW 1.9EW (active ingredient carfentrazone). Aim EW is a liquid formulation that will replace the Aim 40DF dry formulation. The Aim EW use rate of 0.5 fluid ounce per acre is equivalent to the 0.33-ounce-per-acre rate of the dry formulation. Aim is labeled for field corn, seed corn, popcorn, corn silage, sweet corn, grain sorghum, soybean, wheat, barley, and oats.
Spartan 75WDG (active ingredient sulfentrazone). Spartan contains the same active ingredient as Authority for use in soybeans. However, Spartan may be applied up to 8 ounces per acre where Authority is only labeled to 5.3 ounces per acre. Spartan may be applied up to 45 days before planting through 3 days after soybean planting. Spartan should not be applied to emerged soybeans, or severe injury can occur. The higher rates of Spartan will extend control of morningglories, waterhemp, and hophornbeam copperleaf.
Roundup WeatherMax 5.5L (active ingredient glyphosate). Roundup WeatherMax will replace Roundup UltraMax 5L for broad-spectrum weed control in Roundup Ready crops and for nonselective weed control in many cropping systems, farmsteads, and CRP acres. Roundup WeatherMax is a higher-load glyphosate formulation that contains a surfactant. Roundup WeatherMax is formulated as the potassium salt of glyphosate that contains 5.5 pounds of active ingredient (4.5 pounds of acid equivalent per gallon). The 22-fluid-ounce rate of Roundup WeatherMax is equivalent to the 32-fluid-ounce rate of a glyphosate formulation with 4 pounds of active ingredient per gallon (3 pounds of acid equivalent per gallon; i.e., Roundup Ultra).
Yukon 67.5WDG (active ingredients halosulfuron and dicamba). Yukon is a premixture of 12.5% halosulfuron and 55% dicamba that was registered in 2002 for use in field corn, field corn grown for seed, and grain sorghum. The common use rate of Yukon is 4 ounces per acre, which delivers 2/3 ounce per acre of Permit and 4 fluid ounces per acre of Banvel. However, it can be applied up to 8 ounces per acre to control larger weed species in corn (6-ounce maximum rate for sorghum). Applications of Yukon must include either a nonionic surfactant or a COC, but not both. A nitrogen fertilizer (UAN or AMS) may be added to the spray solution; however, it is not required. Two applications of Yukon may be applied to corn per year with a total application not to exceed 8 ounces per acre. Yukon can be applied over-the-top or with drop nozzles from spike through 36-inch-tall field corn and from the 2-leaf stage to 15-inch-tall grain sorghum. Yukon controls both large- and small-seeded broadleaf weeds, with the added benefit of yellow nutsedge control. Because Yukon contains dicamba, special precautions need to be taken when applications are made near dicamba-sensitive species.
Syngenta Crop Protection, Inc.
Callisto 4SC (active ingredient mesotrione). The Callisto rotation restrictions for alfalfa, dry beans, snap bean, peas, sugar beets, and cucurbits have been changed to 18 months.
Lumax 3.95L (active ingredients S-metolachlor, mesotrione, and atrazine). Lumax is a recently registered premixture containing 2.68 pounds of active ingredient per gallon of S-metolachlor (Dual II Magnum), 0.268 pound of active ingredient per gallon of mesotrione (Callisto), and 1.0 pound of active ingredient per gallon of atrazine. Lumax is a selective preemergence herbicide that controls annual grasses, annual broadleaf weeds, and sedges in field, seed, and silage corn. Lumax may be applied up to 10 days before planting (EPP), PRE, and EPOS up to corn 5 inches in height. Application rates range from 2.5 to 3.0 quarts per acre depending on soil texture and soil organic matter content. A typical use rate of 3.0 quarts per acre of Lumax is equivalent to applying 2 pints of Dual II Magnum, 6.4 fluid ounces of Callisto, and 0.75 pound of active ingredient per acre of atrazine.
Gangster (active ingredients flumioxazin and cloransulam-methyl). Gangster is a multipack of Gangster V (flumioxazin, Valor) and Gangster FR (cloransulam-methyl, FirstRate) for use in soybeans. Gangster can be applied from 14 days prior to planting to 3 days after planting at rates ranging from 3.1 to 3.6 ounces per acre. Gangster should not be applied to emerged soybeans, or severe injury will occur. Gangster will provide residual control of a number of broadleaf weeds.
Phoenix 2EC (active ingredient lactofen). Phoenix is a new formulation of lactofen, which is the active ingredient in Cobra. Phoenix contains 2 pounds per gallon of lactofen plus an adjuvant system. Use rates range from 8 to 12.5 fluid ounces per acre, and applications should include 0.125 to 0.25% (v/v) nonionic surfactant. A COC may be used at 1 pint per acre if weeds are under stress due to hot and dry conditions. The addition of a COC causes soybean leaf burn similar to Cobra. Phoenix with a nonionic surfactant also causes some leaf bronzing or speckling; however, it may not be to the same extent as Cobra. The rainfastness of Phoenix is 2 hours compared with Cobra's 1/2 hour.--Christy Sprague and Aaron Hager