Table 2.2-7. Characteristics of "burndown" herbicides for no-till corn
See Table 2.2-6 for relative effectiveness of these treatments. May need to combine with residual treatment or postemergence program (Tables 2.2-10 and 2.2-13) for complete no-till weed-control program.
| Herbicide¹ | Rate/A | lb ai/A | Comments |
|---|---|---|---|
|
|||
| 2,4-D LVE 4E | 1 pt | 0.5 | Apply 7–14 days before planting or 3–5 days after planting for greater crop safety. Plant corn at least 1.5 inches deep. Add Clarity to increase effectiveness on legume sods. This product is poor on chickweed, henbit, red dead nettle; ineffective on all grasses. |
| 2,4-D LVE 4E | 0.5–1 pt | 0.25–0.5 | Apply 7–14 days before planting or 3–5 days after planting for greater crop safety. Plant corn at least 1.5 inches deep. A combination of 2,4-D + Clarity/Banvel controls most annual broadleaf weeds and alfalfa. Emerged perennial broadleaves are partially controlled. This combination is fair on chickweed, henbit, and red dead nettle; ineffective on all grasses. |
| + | + | + | |
| Clarity 4S/ Banvel 4S (dicamba) | 0.5–1 pt | 0.25–0.5 | |
| Atrazine 90DF | 1.8–2.2 lb | 1.6–2 | Apply 1.6–2 qt atrazine 4L prior to planting. Controls small emerged annual broadleaves and some grasses. Can be applied in liquid nitrogen as the carrier to improve burndown characteristics. See atrazine use restrictions at the end of this table. (Restricted-use pesticide and water quality advisory) |
| Atrazine 4L | 1.8–2.2 lb | 1.6–2 | Adding 2,4-D improves control of broadleaf weeds. See the atrazine and 2,4-D comments. See atrazine use restrictions at the end of this table. (Restricted-use pesticide and environmental hazard warning) |
| + | + | + | |
| 2,4-D LVE | 1 pt | 0.5 | |
| Autumn 10WDG (iodosulfuron) | 0.3 oz | 0.03 oz | Autumn may be applied after fall harvest and up to 30 days prior to corn planting. Do not apply to frozen ground. Apply to actively growing weeds. Autumn will provide short-term residual control of small seeded broadleaves but will not provide season-long pre control of annual grasses and broadleaf weeds. Apply Autumn at 0.3 oz/A plus necessary adjuvants. For enhanced burndown activity, tank-mix with 2,4-D, glyphosate, paraquat, simazine, or metribuzin. Be cautious of crop rotation restrictions. |
| Expert 4.88L (s-metolachlor atrazine + glyphosate) | 2.5–3.75 qt | 3.05–4.58 | Expert is a premix of metolachlor (Dual II Magnum), atrazine, and glyphosate. The 3 qt. rate contains 1.3 lb s-metolachlor, 1.6 lb atrazine and 0.75 lb ae glyphosate. Expert can be used as a burndown/pre program in corn or as an early post application in Roundup Ready hybrids. See Expert label for additional information. (Restricted-use pesticide and water quality advisory) |
| Gramoxone SL 2S (paraquat) | 2–4 pt | 0.5–1.0 | Apply in 20–60 gal/A for control of emerged annual weeds. Add 16–32 oz nonionic surfactant/100 gal of spray. Phosphate-containing liquid fertilizer solutions diminish paraquat activity if used as a carrier. Use appropriate precautions when handling paraquat to minimize exposure to the herbicide. Do not use flood jet tips larger than size 20 or spacing greater than 40 inches. (Gramoxone is a restricted-use pesticide.) |
| Gramoxone SL 2S (paraquat) | 2–4 pt | 0.5–1.0 | See comments under Gramoxone. Adding 2,4-D or Clarity/Banvel improves control of large annual broadleaf weeds and alfalfa. Alfalfa control is improved by applying 2,4-D or Clarity/Banvel separately at least one day ahead of paraquat. (Gramoxone is a restricted-use pesticide.) |
| + | + | + | |
| 2,4-D LVE | 1 pt | 0.5 | |
| or | or | or | |
| Clarity 4S/ Banvel 2S (dicamba) | 0.5 pt | 0.25 | |
| Gramoxone SL 2S (paraquat) | 2–4 pt | 0.5–1 | Adding atrazine to paraquat can improve control of fescue and certain other perennial sods. See atrazine use restrictions at the end of this table. (Restricted-use pesticide and water quality advisory) |
| + | + | + | |
| Atrazine 90DF | 1.1–2.2 lb | 1–2 | |
| Harmony Extra SG 50DF (thifensulfuron + tribenuron) | 0.45–0.9 oz | 0.014–0.028 | Adding Harmony Extra to glyphosate or 2,4-D can improve control of certain winter annual broadleaves and perennials. Must be applied in fall or early spring at least 14 days ahead of planting. |
| Hornet 78.5WDG (flumetsulam + clopyralid) | 3-5 oz |
0.13–0.21 | See Table 2.2-10 for comments about Hornet. |
| Glyphosate² | See Table 2.2-1a | Fall applications of glyphosate are better than spring applications for control of orchardgrass sods and quackgrass. If controlling orchardgrass sod in spring it is best to spray when sod is 6 to 10 inches tall. Use at least 1.13 lbs ae glyphosate or higher, especially if tank-mixing with preresidual herbicide and nitrogen carriers. Spring applications may be used for control of annual weeds. Using low-volume sprays may allow for a reduced rate. For control of small annual weeds or volunteer small grains, glyphosate may be used at reduced rates. Glyphosate may be applied in clear liquid nitrogen fertilizers and clear liquid complete-analysis fertilizers, but may be less effective on certain annual grasses and perennials. Do not use glyphosate with suspension-type liquid fertilizers. | |
| Glyphosate | See Table 2.2-1a | Adding 2,4-D or Clarity/Banvel improves control of large, annual broadleaf weeds, dandelion, and alfalfa. See previous glyphosate, 2,4-D, or Banvel comments. | |
| + | + | + | |
| 2,4-D LVE | 1 pt | 0.5 | |
| or | or | or | |
| Clarity 4S/Banvel 4S (dicamba) | 0.5 pt | 0.25 | |
| Glyphosate | See Table 2.2-1a | When tank-mixing glyphosate with residual herbicides, apply in 10–20 gal water/A or 10–60 gal liquid fertilizer nitrogen/A. Glyphosate may be applied in clear liquid nitrogen fertilizers and clear liquid complete-analysis fertilizers. Do not use glyphosate with suspension-type liquid fertilizers. Roundup activity may be reduced when tank-mixing with residual herbicides that have contact activity on emerged weeds. See atrazine use restrictions at the end of this table. (Restricted-use pesticide and water quality advisory) | |
| + | + | + | |
| Atrazine 90DF | 1.1–2.2 lb | 1–2 | |
| Metribuzin 75DF/4L |
2–5.3 oz DF | 0.094–0.25 | Include metribuzin as part of an herbicide program for burndown of existing vegetation prior to crop emergence. Metribuzin may be tank-mixed with 2,4-D LVE, Gramoxone, or glyphosate. Use a maximum of 4 oz DF if applying less than 10 days before planting or on soils with less than 2% organic matter. Do not use on coarse soils with less than 1.5% organic matter or on soils having pH 7.0 or greater. Plant corn at least 1.5 inches deep to avoid injury. (Water quality advisory) |
| Sharpen 2.85SC (saflufenacil) | 1–3 fl oz | 0.022–0.067 | Sharpen may be applied as a preplant/burndown treatment from 14 days early preplant through preemergence timings. Apply Sharpen (1 oz/a) in a typical glyphosate burndown herbicide program to enhance the speed of burndown and increase weed spectrum including glyphosate-resistant horseweed. Depending on the rate, Sharpen can provide some short-term residual control of certain annual broadleaf weeds. Include necessary additives MSO or COC plus nitrogen solution or AMS to the spray mixture. Do not apply to emerged corn or if OP or carbamate insecticides are being used. Sharpen is a Group 14 herbicide, and due to concerns for long-term viability of this herbicide mode of action, extension specialists in the Mid-Atlantic region recommend not using it every year. This mode of action has greater utility in soybeans than corn, especially for control of glyphosate-resistant horseweed (marestail). As such, we suggest that Sharpen and other saflufenacil-containing products (e.g., Verdict, Optill) be used in soybean first and only in alternate years. The use of Sharpen in continuous corn should also be limited to every other year (alternating years with HPPD-containing herbicide [Group 27]) and avoided if Sharpen is used in soybean in a corn–soybean rotation. |
| Valor SX 51WDG (flumioxazin) | 1–2 oz | 0.51–1.02 oz | Valor may be included in a typical no-till burndown herbicide program to enhance the speed of burndown and increase weed spectrum. Corn can be planted 7 days after application if there is at least 25% soil residue cover and ¼ inch rainfall. Fierce 76WDG contains the active ingredients in Valor and Zidua and can be used in burndown programs; see Table 2.2-10 for additional details. Valor is a Group 14 herbicide, and due to concerns for long-term viability of this herbicide mode of action, extension specialists in the Mid-Atlantic region recommend not using it every year. This mode of action has greater utility in soybeans than corn, especially for control of glyphosate-resistant horseweed (marestail). As such, we suggest that Valor and other flumioxazin-containing products (e.g., Fierce, Valor XLT, Envive) be used in soybean first and only in alternate years. The use of Valor in continuous corn should also be limited to every other year (alternating years with HPPD-containing herbicide [Group 27]) and avoided if Valor is used in soybean in a corn–soybean rotation. |
Atrazine Use Restrictions
Preplant or Preemergence
On highly erodible soils (as defined by the U.S. Natural Resources Conservation Service):
- Fields where more than 30 percent of the soil surface is covered with plant residue at planting, apply a maximum of 2.0 lb of active ingredient per acre as a broadcast spray.
- Fields where less than 30 percent of the soil surface is covered with plant residue at planting, apply a maximum of 1.6 lb of active ingredient per acre as a broadcast spray.
- Apply a maximum of 2.0 lb of active ingredient per acre as a broadcast spray.
Postemergence
- If no atrazine was applied prior to crop emergence, use a maximum rate of 2.0 lb of active ingredient per acre.
- If a soil-applied application was made in the same calendar year, the combined preplant or preemergence and postemergence applications may not exceed 2.5 lb of active ingredient per acre.
Safety Precautions for Using Atrazine
- Do not mix, load, or apply within 50 feet of drinking water wells, livestock wells, agricultural drainage wells, irrigation wells, abandoned wells, or sinkholes.
- Do not mix or load within 50 feet of intermittent streams, perennial streams, rivers, lakes, or reservoirs.
- Do not apply within 200 feet of lakes or reservoirs.
- Do not apply within 66 feet of the points where surface water runoff enters intermittent streams, perennial streams, or rivers. The 66-foot buffers should be planted to a crop or seeded with grass on highly erodible land.
