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No Roundup or Liberty? Here are some options

Chris Evans, U of I, Bugwood.org common ragweed
COMMON RAGWEED: There are options outside of Roundup for common ragweed and other pesky weeds in corn and soybeans.
Whatever alternative you use depends on the weed you are targeting.

Here are some best bets for selected problem weeds in corn and soybeans.

For simplicity, the common trade names are used in the table below. Herbicides that typically provide at least 85% control or more have been included. But there are many generic equivalents that can be used as well as tankmixes of active ingredients that can provide adequate control.

Remember that some of these weed species have populations that are resistant to certain herbicide sites of action, so keep this in mind when developing herbicide programs.

1122T2-3744table

Burndown alternatives to glyphosate include Harmony Extra, Canopy EX/DF, Basis Blend, Sharpen, Reviton, metribuzin, simazine, dicamba, Elevore, clethodim, Assure II/Targa, Aim, Scythe and others.

Keep in mind that, without glyphosate in the mix, weed control will not be as robust, especially for grass weeds and cover crop termination.

Only a limited number of corn and soybean herbicides allow you to switch crops, if necessary.

Burndowns

Here are some options:

2,4-D LVE. When applied at 1 pint per acre, there is a seven-day waiting period for non-Enlist soybeans. Higher rates can be used but will require longer waiting periods to plant. In Enlist beans, no preplant interval is required if you use the 2,4-D choline (Enlist One/Duo) products. 2,4-D has activity on many broadleaf weeds, including dandelions, burdock, marestail, mustards and thistles. It is weak on chickweed, milkweed, dogbane, fleabanes, henbit, deadnettle and field pansy.

Basis blend. Apply it at 0.825-2.5 ounces per acre before corn emergence. In soybeans, apply at 0.825 ounces 15 days or more before planting. It has activity on many common broadleaf and grassy spring weeds, but tank-mix to enhance control.

Dicamba. Apply at 8-16 fluid ounces per acre at least seven to 14 days before corn planting. In non-Xtend soybeans, wait at least 14 days to plant with 4 fluid ounces dicamba and 28 days for 8 fluid ounces. For Xtend, no preplant interval is required if Engenia, Xtendimax or Tavium is sprayed. Dicamba has activity on many broadleaves, but it is weak on dandelions, chickweed, mustards, fleabanes and field pansy.

Ohio State Weed Lab , OSU, Bugwood.orgburcucumber

BURCUCUMBER: Not every weed can be treated the same. Burcucumber, for example, requires a two-pass program.

Elevore. Corn or soybeans can be planted 14 days after application when applied at 1 fluid ounce per acre. It provides control of glyphosate-resistant marestail, henbit and deadnettle, but is weak on other weeds at burndown.

Glyphosate. This can be used in burndown and post in Roundup Ready crops. Increase the rate to 1.5 pounds per acre for larger weeds when necessary. In times of shortage, though, use the lower rate of 22 fluid ounces of PowerMax instead of 32 fluid ounces to conserve product and cover more acres.

Gramoxone 3.0 SL/Paraquat 3 pounds per gallon. You can increase the rate to 2.7 pints per acre for larger weeds. You can also tank-mix with metribuzin, plus 2,4-D, and still be able to plant corn or soybeans. This mixture provides better burndown activity than paraquat alone, especially on marestail.

Harmony Extra. This can be added to glyphosate, 2,4-D, or dicamba burndown at 0.45-0.90 ounces per acre for both corn and soybeans to improve control of chickweed, henbit/deadnettle, mustards, dock and Canada thistle. You must wait seven days to plant soybeans and 14 days for corn.

Liberty 280. It is labeled up to 43 fluid ounces per acre in burndown. Liberty is most effective on small, actively growing weeds under warm temperatures. Use sufficient carrier volume (minimum 15 GPA) and smaller-droplet spray tips to get thorough coverage of the weeds.

Reviton. This is labeled for both corn and soybeans at a rate of 1-3 fluid ounces per acre. Corn can be planted immediately, but wait 14 days for soybeans. It is less active on marestail but has some grass activity.

Select/clethodim. This can be applied at reduced rates six days before corn planting to control volunteer corn and other grassy weeds. There are no restrictions before soybean planting.

Sharpen. It is labeled for corn and soybeans. Use only at 1 ounce per acre in soybeans and add MSO as the adjuvant if immediately planting soybeans. Higher rates can be used, but beware of planting restrictions, especially for soybeans. It provides good control of marestail, but it tends to be weaker on several other key burndown weeds.

Grass residuals

Here are some options:

Dual. This can be used in both corn and soybeans for residual grasses, yellow nutsedge and some small-seeded broadleaf control.

Outlook. This can be used in both corn and soybeans for residual grasses and certain small-seeded broadleaf control.

Warrant. This can be used in both corn and soybeans for residual grasses, yellow nutsedge and small-seeded broadleaf control.

Broadleaf residuals

Here are some options:

Lorox. This can be used in both corn and soybeans. It provides control of annual broadleaves but can suppress certain annual grasses.

Metribuzin. This product was labeled preemergence at up to 5.3 ounces per acre on medium-textured soils with greater than 2% organic matter as part of the burndown program.

Python. It is effective on a number of annual broadleaf weeds and can be used in both corn and soybeans. The use rate range is 0.8-1.14 ounces per acre (up to 1.33 ounces in soybeans).

Valor. Corn may be planted seven days after application at the 2-ounce-per-acre rate (requires minimum 25% surface residue and 0.25 inches of rainfall between application and planting). Do not tank-mix with common grass herbicides in soybeans due to injury concerns.

Grass and broadleaf residuals

Here are some options:

Verdict. This is a mixture of the active ingredients found in Sharpen and Outlook. The most common application rate is 13 fluid ounces per acre for corn and 5 fluid ounces per acre for soybeans.

Zidua and Anthem Maxx. This can be used in the burndown mix. Either corn or soybeans can be planted and will provide control of many annuals.

Fierce. This can be used in both soybeans and no-till or minimum-till corn to control many annual grasses and broadleaves. In corn, you must wait at least seven days to plant corn after application.

Combinations that include a grass product (Dual, Outlook and Warrant) plus Python would also provide residual grass and broadleaf control for both corn and soybeans.

Lingenfelter is an Extension associate of weed science with Penn State Cooperative Extension.

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