Broadleaf Weed Control

Soil-applied Broadleaf Herbicides (Triazine Family)

atrazine (Aatrex 4L): 1 qt/A (REI 12h, Group 5). Apply preplant incorporated or to the soil surface immediately after planting. Use alone only if annual grasses are not a problem. Shallow cultivation may help to control annual broadleaf weeds. May be tank mixed with butylate, EPTC + safener, alachlor, metolachlor, glyphosate or paraquat.

simazine (Princep 80WP): 2-1/2 to 3-3/4 lb/A (REI 12h, Group 5). Apply preplant incorporated or to the soil surface immediately after planting. Use alone only if annual grasses are not a problem. May be tank mixed with EPTC + safener.

Soil-applied Broadleaf Herbicide (Newer Chemistry)

mesotrione (Callisto 4EC): Apply 6.0 to 7.7 oz/A (45 dh, REI 12h, Group 28). Apply after seeding to the soil surface. Use 5 to 6 oz/A if tank mixing with atrazine. In a tank mix, the atrazine rate can be reduced to 0.5 to 1 pt/A. A grass herbicide must also be used. Callisto provides excellent control of many problem broadleaf species such a velvetleaf and triazine-resistant lambsquarters. On cool soils in the spring, Callisto may be a better option than using Prowl to control these two weed species. Callisto does not provide preemergence control of yellow nutsedge. With this weed, it is important to continue to use atrazine (alone or in combination with Callisto) as well as either Dual or Lasso preemergence. A preplant incorporated application of either Eradicane or Sutan+ will also have activity on yellow nutsedge. See the label for precautions and more information on tank mixes, rates, and weeds controlled.

Postemergence Applied Broadleaf Herbicides

ametryn (Evik 80W): 2 to 2 1/2 lb/A (REI 12h, Group 5). Apply as a postemergence directed spray on weeds after corn is at least 12” tall. Do not spray overtop of corn. Do not spray within three weeks of tasseling. See label for additional precautions and specific information on weed size and proper rate. Evik should be primarily used as an emergency treatment when grasses and broadleaf weeds are emerging and the use of 2,4-D is not desirable.

atrazine (Aatrex 4L): 1 qt/A, (REI 12h, Group 5). Add either 1 qt/A of crop oil concentrate or 1 gal/A of spray oil. Apply when weeds are 1 to 1 1/2” high and before corn is 12” high. This treatment can be used as the primary broadleaf herbicide treatment instead of an application at planting or it can be used as an emergency treatment if the soil-applied broadleaf herbicide treatment failed. If applied correctly, this application will control the emerged weeds and will continue to provide residual control for later-emerging broadleaf weeds. Check label for additional precautions regarding the use of crop oil and petroleum oils.

bentazon (Basagran 4E): 1 1/2 pt/A (REI 48h, Group 6). Apply early post-emergence overtop when weeds are small and corn has one to five leaves. See label for ideal weed size. Bentazon will not control redroot pigweed and will provide only partial control of common lambsquarters, giant ragweed and morning glory. Bentazon should be primarily used as an emergency treatment when a soil-applied broadleaf herbicide has failed. There is less chance of adjacent crop injury from spray drift than with 2,4-D.

carfentrazone (Aim 40 WG): 0.33 to 0.67 oz/A (REI 12h, Group 14). Apply before corn reaches 8” in height to control seedling broadleaf weds including pigweed, common lambsquarters, eastern black nightshade, and velvetleaf. Tank mix with atrazine at reduced rates or another broadleaf herbicide to increase the spectrum of weeds controlled. Add non-ionic surfactant at a rate of 1 qt/100 gal spray solution. Expect to see speckling of the crop foliage after application. Initially, the injury appears to be substantial, but it is not systemic and the corn outgrows the injury rapidly. Cultivar sensitivity may vary with Aim. Use caution when treating new cultivars. Weather conditions may also affect the degree of injury observed. Injury may be more severe during periods of warm, cloudy weather with high humidity and plentiful soil moisture when corn growth is rapid and soft. If corn is over 8” tall, use drop nozzles to avoid spraying both into the whorl and the corn foliage.

halosulfuron (Sandea 75 WSG): 2/3 to 1 1/3 oz/A (REI 12h, Group 2). This herbicide provides postemergence control of many weed species which are not under drought stress. It is rainfast in 4 hours. Use a non-ionic surfactant at a rate of 1 to 2 qt/100 gal spray or a crop oil concentrate at 1 gal/100 gal spray. Control varies with type and size of weed. Species listed on the label include redroot pigweed, pokeweed, common ragweed, Pennsylvania smartweed, common sunflower, velvetleaf, wild mustard, yellow nutsedge, and wild radish. Do not cultivate for 7 days after application. Most vegetables can be planted within 12 months of application except crucifers, carrot, leeks, onions, lettuce, beets, and spinach. Some sweet corn varieties may be injured by Permit and no reliable list of susceptible varieties has yet been developed. Regular sugary varieties do not appear to be more tolerant than se (sugar enhanced) types or sh2 (supersweet) types. Initially, this herbicide should be used on a small scale to control problem weeds such as yellow nutsedge, ragweed and velvetleaf, and triazine-resistant lambsquarters. Other postemergence options continue to exist. These include Aatrex (atrazine), Basagran (bentazon), Amine 4 (2,4-D), Lorox (linuron), and Evik (ametryn). Atrazine, Basagran, and 2,4-D have been the most commonly used.

linuron (Lorox 50 DF): 1 1/4 to 3 lb/A (REI 24h, Group 7) Use only as a postemergence-directed treatment to corn at least 15” high. Use lower rates on weeds less than 2” in height and higher rates on weeds up to 5” in height. Add 1 pt of surfactant for each 25 gals of spray mixture.

mesotrione (Callisto 4EC): Apply 3 oz/A (45 dh, REI 12h, Group 28). Apply postemergence to corn (up to 30” tall) when weeds are no more than 3” tall. Do not make more than 2 applications per season to corn and do not exceed a total of 7.7 ounces per acre of Callisto. Callisto provides excellent control of many problem broadleaf species such a velvetleaf and triazine-resistant lambsquarters. Callisto provides only partial control of yellow nutsedge and no control of ragweed when applied postemergence. Use other options if these weeds are present. See the label for precautions and more information on tank mixes, rates, and weeds controlled.

2,4-D amine (Amine 4): 0.5 to 1 pt/A (REI 48h, Group 4). Use 0.5 pt/A when weeds are small and corn is 4” to 5” tall. Increase rate to 1 pt/A as corn reaches 8” tall. Use drop nozzles to direct spray toward base if corn is over 8” tall. Do not cultivate for about 10 days after spraying, as corn may be brittle. Reduce rate of 2,4-D if temperature is hot and soil is wet. Use only the amine formulation of 2,4-D; Do not use any ester or low-volatile ester formulations. Use all precautions to avoid spray drift to desirable broadleaf crops.

pelargonic acid (Scythe 4.2): 3% to 10% (REI 24h, Group 27). Use a 3-5% solution for annual weeds (4-6 oz/gal water), a 5-7% solution for biennial and perennial weeds (6-9 oz/gal water), and 7-10% solution for maximum burndown (9-13 oz/gal water). Delivery rate for boom applications should be 75 to 200 gal spray solution/A; complete coverage of weed foliage is essential. Use a DIRECTED/SHIELDED SPRAY; contact with crop will cause injury. For hand-held equipment, spray to completely wet all weed foliage but not to the point of runoff. Repeat applications as necessary. Tank mixes are allowed with this product. These include tank mixes with glyphosate (Roundup), sulfosate (Touchdown), and residual herbicides. See label for complete details.

tembotrione (Laudis):  0.082 lb/A  (REI 12 hr, Group 27)  Apply 3 fluid ounces of Laudis per acre postemergence to control many annual broadleaf weeds, including common lambsquarter and triazine-resistant broadleaf weed biotypes, and many annual grasses.  Add oil methylated seed oil (MSO)  or concentrate (COC) to be 1% of the spray solution (1 gallon per 100 gallons of spray solution).  In addition, the label requires the addition of nitrogen liquid fertilizer (1.5 quarts per acre) or AMS (1.5 pounds per acre).  Tank mix with 0.25 to 1 lbs ai/A of atrazine for improved control and to broaden the spectrum of weeds control.  Local university data supports the use of at least 0.5 lb ai/A of atrazine.  Do not apply tank-mixes of Laudis and atrazine to corn greater than 12 inches tall.  Do not use postemergence if Callisto, Lumax or Lexar was used preemergence.  Do not tank-mix with Callisto.  Laudis will control/suppress most annual grass species, but may not control certain grass species or grasses larger than the maximum recommended size when treated.  Fall panicaum is not controlled by Laudis.  Most broadleaf weeds should be treated before they are 6 inches tall and grass weeds should be treated before 2 inches in height.  Laudis has up to an 18 month replant restriction for many vegetables.

topramezone (Impact 2.8SC):  0.016 lb/A  (REI 12 hr, Group 28)  Apply .75 fluid ounces of Impact 2.8SC per acre postemergence to control many annual broadleaf weeds, including common lambsquarter and triazine-resistant broadleaf weed biotypes, and annual grasses.  Add oil concentrate (COC) to be 1% of the spray solution (1 gallon per 100 gallons of spray solution).  In addition, the label requires nitrogen fertilizer (liquid or AMS),.  Tank mix with 0.25 to 1 lbs ai/A of atrazine for improved control and to broaden the spectrum of weeds control.  Local university data supports the use of at least 0.5 lb ai/A of atrazine.  Do not apply tank-mixes of Impact and atrazine to corn greater than 12 inches tall.  Do not use postemergence if Callisto, Lumax or Lexar was used preemergence.  Do not tankmix with Callisto.  Impact will control/suppress crabgrass and most other annual grass species, but may not control certain grass species or grasses larger than the maximum recommended size when treated.  Most broadleaf weeds should be treated before they are 6 inches tall and grass weeds should be treated before 2 inches in height.  Impact has an 18 month replant restriction for most vegetables.

Postemergence Grass Control

nicosulfuron (Accent Q 55WDG):  0.45 to 0.9 oz/A (REI 4h, Group 2).  Apply as a broadcast application when grasses are young and actively growing to corn that is less than 12” high or up to and including 5 leaf collars.  If corn is 12” to 18” high, applications must be made with drop nozzles.  Make only one application per year.  Applications must include either a non-ionic surfactant or crop oil concentrate.  An ammonium nitrate nitrogen fertilizer must also be used unless the label of a potential tank mix partner prevents it.  Do not apply if corn is greater than 18 inches of 6 leaf collars.  Not all sweet corn varieties are tolerant to Accent.  Check with the Dupont representative or Extension for further information.  Also see the label for optimum sizes of grasses.