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Prairie Grains is the official publication of
the Minnesota
Association of
Wheat Growers,
North Dakota Grain Growers Association,
South Dakota Wheat, Inc., and the Minnesota Barley Growers Association.

Tiller (fenoxaprop-P, 2,4-D, MCPA) can be applied to winter and spring wheat when wheat begins to tiller (3- to 4-leaf stage) up to the 6-leaf stage for control of green foxtail, foxtail millets, volunteer corn, common lambsquarters and wild mustard at 1 pt/A. Tiller at 1.2 pt/A controls those weeds plus yellow foxtail, volunteer and proso millet. Tiller at 1.7 pt/A controls those weeds plus wild oats, barnyardgrass and several broadleaf weeds. Tiller should be applied to young, vigorously growing weeds. Tiller received a label on barley last year. Barley has only fair tolerance to Tiller, thus, consider 1.2 to 1.5 pt/A on barley before jointing to prevent crop injury. Some yellowing and stunting is a normal response of barley to Tiller. It is important not to apply Tiller to wheat or barley after jointing begins.

Starane (fluroxypyr) is one of two new broadleaf herbicides labeled for small grains. It should be applied when the crop is at 2-leaf through flag emergence, and when weeds are 4 to 6 inches tall. Starane applied at a 2-oz. rate is very effective on kochia even at eight inches tall. It is a systemic herbicide with no soil carryover, so it can be used to clean up a kochia problem before planting crops the following year, such as canola or sugarbeets. Starane + Salvo (2,4-D ester) and Starane + Sword (MCPA ester) are premixes for more broad-spectrum broadleaf weed control, at slightly different application windows.

Aim (carfentrazone) is another new post-emergence broadleaf herbicide labeled for spring wheat this year. It is not labeled for barley because of a crop tolerance problem. It controls kochia, cocklebur, lambsquarters, nightshade, and pigweed. Aim needs to be applied with another broadleaf herbicide for broad-spectrum weed control. There is no label for tank mixing it with wild oat herbicides. It has no soil residual so it can be used to clean up a kochia problem before planting crops like canola or sugarbeets.

Avenge (difenzoquat) is a wild oat herbicide that is not a new product, but whose label should be followed closely for cleared spring wheat varieties. Avenge can be used on all barley and winter wheat varieties and all durum varieties except Vic, Fjord, Edmore, Lakota, Renville and Wascana. But for spring wheat, use Avenge only on varieties and at rates listed on the label, or crop injury may occur. Wild oats is more susceptible to Avenge at the 5-leaf than the 3-leaf stage of growth.

Puma (fenoxaprop-P + safener) is another new product this year. At 0.33 pt/A, Puma controls green foxtail, foxtail millets, and volunteer corn; at 0.4 pt/A, it controls yellow foxtail, foxtail and proso millet, and at 0.67 pt/A, it controls barnyard grass and has good activity against wild oats. It should be applied when the crop is 2-to-6 leaf, and grass weeds are 2-leaf to 2-tiller. It should not be applied to wheat after jointing begins. Puma has the same active ingredients as Cheyenne and Tiller, but contains a safener for better crop tolerance. Puma has no broadleaf activity by itself, but has several broadleaf tank-mixing options.

Achieve (tralkoxydim) is a new product labeled for wild oats and foxtail control on wheat, barley and durum. It should be applied when the crop is 2-leaf to boot; when foxtails are in the 1-to-5 leaf stage; and wild oats in the 1-to-6 leaf stage. Achieve is packaged as one box containing the product and adjuvant in separate containers for 40 acres. Grass weeds should be actively growing at application. Achieve can be tank-mixed only with MCPA ester, bromoxynil, bromoxynil + MCPA, 2,4-D ester, and Curtail M. Small grains have good tolerance to Achieve.

For more comprehensive information on weed control information and options, contract your county extension office.

Manage spray program to prevent weed resistance
Manage spraying decisions to minimize potential for herbicide resistance, says Dr. Bev Durgan, University of Minnesota extension weed specialist, St. Paul.

Though it still is not a widespread problem, more incidents are occurring, with herbicide-resistant kochia, wild oats, foxtails, and several broadleaf weeds found in Minnesota, North Dakota, and other states.

Resistant kochia can be expressed after three to five applications of the same herbicide, and resistant green foxtail and wild oats can be expressed after eight to 12 herbicide applications.

One concern that Durgan believes should be watched closely is whether the increased use of genetically-engineered, herbicide-resistant crops (Roundup Ready, Liberty Link) may lead to a greater incidence of herbicide-resistance weed species. For example, quackgrass tolerant of glyphosate (Roundup), has been documented in northwest Minnesota. The quackgrass is not resistant to glyphosate, but has an increased tolerance of the product.

Strategies that help minimize herbicide-resistant weeds:
• Rotate crops, particularly those with different life cycles.
• Rotate herbicides with different modes of action in consecutive years.
• Apply herbicides in tank-mix, prepackage or sequential mixtures that include multiple modes of action.
• Combine mechanical weed control practices with herbicide treatments.
• Scout fields, identify weeds that escape treatment, and hand remove surviving weeds to prevent seed production of resistant plants.

Tips for more successful weed control
The best guide to predicting this year’s weeds is to review what was in the field the last year or two, says Leon Wrage, South Dakota State University extension weed specialist. "If you had perennials like Canada thistle or field bindweed, it’s a good bet they’ll be there again," he says.

Good seed, uniform planting depth, full population and narrow rows all help limit weed competition, says Wrage. Take advantage of residual herbicides to help in the following crop year if the weed is tolerant: Carryover isn’t always bad. Also, don’t underestimate the importance of proper tank mixing and application timing for optimum weed control.

Early planted spring crops means more pressure from early weeds like wild oats, but gives spring planted cereals a competitive advantage of late-emerging weeds like foxtail. Wrage suggests planning for a wide application window to allow for weather delays. Split preplant or premergence application with postemerge or split postemergence to get more consistency in variable conditions or for mixed weed problems.

NDSU soil scientist: Don’t let emotions rule input decisions
Difficult economic times make many people, including farmers, cautious. But while caution can serve as an instinctive defense mechanism, it also functions as an emotion. And when it comes to 1999 fertilizer strategies, it’s more prudent to base decisions on solid information, not feelings and emotion, says Dave Franzen, NDSU extension soil scientist. Several suggestions from Franzen to consider:
• Don’t make strategic fertilizer mistakes: applying unneeded inputs, making unnecessary applications or mis-timing applications.
• Don’t cut corners by scouting one field and then extrapolating that information to other fields.
• Producers should test each field, and may need to test some fields differently. If history indicates that composite soil testing is unreliable, using landscape relationships (hilltops, slopes and depressions) can help pinpoint field fertility levels.
• Nitrogen is necessary for each crop, and phosphorus is necessary for most, but soil levels and the amount required for individual crops vary. Recommendations from consultants or your county extension office will help determine whether cuts are prudent. Other nutrients are highly specific for certain crops. Canola is the only crop with an exceptional requirement for sulfur, which should be in sulfate form to ensure highest yields.
• Chloride treatments on wheat and barley have produced responses, but mainly on soils testing less than 30 pounds/acre and only on certain cultivars. NDSU researchers also have observed chloride responses in corn, but not in other crops.
• Only four crops – corn, dry beans, flax and potatoes – have a special sensitivity to zinc.
• Researchers have identified copper deficiency in ND on wheat in 1998, but a response to copper occurred at only one site, which had sandy soil with a low organic matter content.
• Avoid miracle products advertised to enhance or replace fertilizer. If you do try them, test first on limited acreage.
• Soils with higher organic matter are more forgiving than those with lower organic matter levels. So, a conservative approach to N management in some fields may still result in higher yields in a year with above-normal rainfall, since mineralization of organic matter is higher under moister conditions. But protein percentages might suffer with this approach.
• Crops that should normally receive conservative fertilizer treatments are malting barley and sugar beets, due to quality concerns resulting from excessive N. Dry beans fertilization should also be conservative to avoid excessive vegetation and prevent white mold in some years.

What about boosting N this year to pad wheat yields or protein? "Since protein premiums have not been exciting recently and given the abysmal prices of late, growers may choose to select a more realistic yield goal as a basis for N recommendations. If a 45-bushel yield is relatively easy to attain, choose that as your goal, not some figure that you’ve hit only once in 10 years or so," says Franzen.