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Weed-control prescriptions

What's the best herbicide program for a given field? That depends on whom you ask. We interviewed five farmers from different states. Then we put a call out to Bayer, DuPont and Syngenta to get their reps' unabashedly biased but well-meaning opinions on how they would doctor each program. The differences in each company's off-the-cuff, general recommendations are enlightening. But you know what they say about free advice. Consider it a starting point for your own research with local experts.

Scott McPheeters, Gothenburg, NE

Problem weeds

Waterhemp, velvetleaf and foxtails. Late-emerging lambsquarters and black nightshade seem to be increasing. Triazine-resistant kochia has blown in. We spot-spray ditches and fencerows when we see weeds moving in.

Herbicides used last year

Food corn: Atrazine and Balance

Popcorn: Bicep and Magnum

Soybeans: Authority and Roundup Ultra

We've had good success with our herbicides, and low cost is attractive at about $10 to $15 an acre. We'll often go with reduced rates, especially on popcorn, to get suppression as opposed to total control.

Bayer CropScience

For a few more dollars on corn, McPheeters should add Define to extend grass control later in the season. While he may get by on partial rates, obviously he will see optimum performance when he follows labeled rates. Keeping up with ditches and fencerows can pay for itself by preventing the migration of troublesome weeds into fields.

For soybeans, McPheeters should apply Domain for residual control of grasses and broadleaf weeds. The residual will let him apply Roundup closer to canopy, which reduces the risk of late-season weed flushes.

DuPont Crop Protection

McPheeters should leave his soybean program as is. On corn, with his concerns for keeping costs low and late-emerging weeds, he should keep atrazine in the program. One-third ounce of Basis and 1 lb. of atrazine would serve him well on the food corn acres, but not the popcorn. Irrigation would ensure product activation. And he can cultivate as needed.

Syngenta Crop Protection

Our typical rate on Bicep II Magnum is 2.1 qts./acre. McPheeters must be using a low rate of 1.6 to 1.8 qts. based on the costs he gave. That might be fine if he's satisfied with suppression, but most farmers will want the full rate for better control.

David Linstad, Adams, ND

Problem weeds

Canada thistle, wild oat, kochia, foxtail. Canada thistle seed blows in off adjacent CRP fields. Kochia is becoming ALS resistant.

Herbicides used last year

Wheat: Puma/HarmonyGT, Clarity, preharvest Roundup

The program works well for Canada thistle and is economical. I prefer to keep herbicide cost per acre around $15. I use conventional tillage, on a primarily clay-loam soil.

Bayer CropScience

Linstad should switch to a tankmix of Puma and Bronate Advanced and continue to use a preharvest Roundup application. Bronate Advanced has excellent compatibility with Puma for one-pass control. This tankmix offers a better spectrum of broadleaf control than what Linstad currently uses. In addition, he'll notice that the mixture stays on the crop target and makes for easy sprayer clean-out when rotating to potentially sensitive crops such as sugar beets and potatoes.

Because rotation is a concern, this program provides total flexibility for rotational options, while offering excellent in-crop control of Canada thistle and good kochia control with a unique mode of action. In addition, he'll get broad-spectrum control of other key broadleaves while retaining the excellent grass performance that Puma is known for. Keeping up the tillage will also keep the population of Canada thistle at a minimum.

DuPont Crop Protection

For Linstad's northern area, he should keep his program just the way it is. He's not going to do much better for his low price threshold.

Leonard Korte, Palmer, IA

Problem weeds

Velvetleaf, waterhemp. I haven't noticed any resistance problems or species shifts on my fields.

Herbicides used last year

Corn: Top Notch, Hornet, Callisto

Soybeans: Treflan, First Rate, Flex Star and Select

I don't have any carryover concerns. I use a minimum-till program and feel the herbicides I use give me the best performance value for the money.

Bayer CropScience

With the high pH in Nicollet soil, Korte must avoid atrazine. Because velvetleaf and waterhemp are his primary concerns, we recommend Balance Pro at 2.5 oz./acre on corn (depending on soil type) plus 10 oz./acre Define applied either prior to or after planting before emergence.

DuPont Crop Protection

Korte should go with a total post program on corn. A good mix would include the recommended rate of Steadfast with 1½ oz. of Callisto and 4 oz. of atrazine. For soybeans, Korte should try Authority, which gives better control of waterhemp than what he's using now.

For soybeans, a switch from Treflan and FirstRate to Domain applied prior to planting will offer broad-spectrum residual control of both grasses and broadleaf weeds, especially velvetleaf and waterhemp.

Syngenta Crop Protection

For corn, Korte should try Lumax at 3.0 qts./acre for one-pass, full-season grass and broadleaf weed control. Or, if there is no woolly cupgrass or heavy pressure from cocklebur or giant ragweed, he should go with fall-applied Dual II G Magnum and postemergence Callisto at 3 oz./acre plus Aatrex at ½ pt./acre.

On soybeans, Korte's current program looks fine, but he might substitute Fusion for Select and/or Boundary for Treflan if he's looking for more consistent performance.

Jack Appleby, Atwood, IL

Problem weeds

Waterhemp, mare's tail and pigweed. I'm not sure if this is a resistance problem or if these are just later-germinating weeds.

Canada thistle is under control on our farm thanks to Roundup Ready bean rotation. Glyphos takes it out.

Herbicides used last year

Corn: Callisto with Basis Gold and some Bicep/Balance. We would like to keep cost per acre in the $18 to $21 range.

Soybeans: We plant Roundup Ready beans and hit them with one application of generic glyphos, nothing else. We plant beans in 15-in. rows and spray about 18 to 21 days after planting. Weeds are usually about 3 to 4 in. high at spraying.

On non-Roundup Ready beans, we use Raptor, Fusion and Flexstar.

Bayer CropScience

For mare's tail, Appleby should try adding a residual product to the soybean program. Mare's tail is typically an early germinating weed; however, resistant or tolerant varieties may adapt as they find holes in herbicide programs. We recommend an application of Domain plus 2,4D and COC 7 to 10 days prior to planting.

For a one-pass program in corn, he should consider Balance Pro at 2.5 oz./acre (depending on soil type) plus Define at 10 to 12 oz. Many growers find this program gets them through the season for only about $5 more than he's currently spending.

Because he likes the convenience of a seed/herbicide system in soybeans, the LibertyLink seed system gives these same benefits in corn without drift concerns. At the new 32-oz. rate, Liberty herbicide controls more than 120 grasses and broadleaf weeds for about $16/acre.

DuPont Crop Protection

We wouldn't make any dramatic changes to Appleby's corn program. But noting his concerns about waterhemp, mare's tail and pigweed, his soybean program should switch to straight Authority followed by a full rate of Roundup UltraMax in a two-pass program.

Steve Webb, Needham, IN

Problem weeds

Mare's tail in my Roundup Ready soybeans seems to have developed glyphosate resistance. Winter annuals and late grasses such as panicum, foxtails and crabgrass can make corn harvest difficult. Creeping vine weeds such as trumpet creeper. Triazine-resistant lambsquarters. Pigweed seems to be making a comeback.

Herbicides used last year

Soybeans: Roundup Ready and some STS

Corn: Axiom and Hornet on first-year corn. Lightning, atrazine plus 28% on second-year corn and on fields with johnsongrass history.

100% no-till. No irrigation. Soil types variable.

Bayer CropScience

For corn, we recommend Balance Pro at 2.25 oz./acre (depending on soil type) plus Define at 16 oz./acre + 24 oz. 2,4D ester + 1 qt. COC + 28% or water 7 to 10 days prior to planting. Webb should plant corn with minimal row disturbance and set trash whippers light (if he uses them). Balance Pro offers residual control and will control the triazine-resistant lambsquarters and pigweed. It also burns down winter annuals with the addition of COC.

On the johnsongrass acres, an application of Option postemerge may be necessary.

Because glyphosate-resistant mare's tail is a concern, Webb may want to consider the LibertyLink system in corn. Seed companies have developed many LibertyLink varieties to fit Indiana growing conditions. Start with 2 oz./acre of Balance Pro (depending on soil type) plus atrazine 1 lb./acre and COC 1 qt./acre (crop oil concentrate) to burn down winter annuals and provide residual control with Recharge.

In soybeans, he should try 16 oz./acre of Domain plus 1 pt. 2,4D and COC 10 days prior to planting. Domain and COC will burn down existing weeds, especially winter annuals, and provide enough residual to allow Webb to apply Roundup later and closer to soybean canopy. This eliminates the need for two Roundup trips.

DuPont Crop Protection

For winter annuals, Webb should look at some fall-applied programs for both soybeans and corn. For mare's tail control in soybeans, he should try a fall application of Canopy Xcel and 2-4D before planting Roundup Ready soybeans the following spring.

For corn, he should consider a fall-applied application of ½ oz. Basis and a pint of 2-4D on bean stubble as needed. This should also help keep triazine-resistant lambsquarters under control on the following season's corn. In the spring, he should use a 14-oz. rate of Basis Gold with 1½ oz. of Callisto.

Syngenta Crop Protection

For bindweed and trumpet creeper, Webb needs to apply Touchdown at 2 qts./acre when these weeds are flowering.

A fall application of Canopy XL can control winter annual weeds and mare's tail. If Webb plants early enough, he may not have too many weeds to burn down.

STS beans will require more management and likely higher cost than Roundup Ready beans. Webb should try 1 qt. Touchdown plus 2,4-D for burn down. He should consider Boundary for residual grass control and later application of post herbicides. He should use Synchrony STS plus Fusion at 10 oz. plus Flexstar at 12 to 16 oz. Flexstar will provide improved activity on vines, pigweeds and waterhemp and help manage ALS resistance.

For corn, he should go with Lumax at 2.5 qts. plus 1 qt. Aatrex for burn down of small broadleaf weeds and grasses (must add crop oil). Lumax provides season-long control of grasses, triazine-resistant lambsquarters and pigweeds. Initial cost may be higher, but it should eliminate the need for a post application.

If johnsongrass, trumpet creeper and field bindweed are problems in corn, then the only effective program will be a two-pass program. Webb should use Bicep II Magnum at 2.1 qts. preemergence plus 2,4-D if grasses are less than 1.5 in. If grasses are taller, then he should add 1.7 pts. Gramoxone Max. NorthStar at 5 oz. postemergence will control johnsongrass and suppress bindweed and trumpet creeper.

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