North Dakota State University Extension Service - Burke County |
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Burke County AgAlert |
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May 10, 2005 Flax Weed Control Options for 2005 Flax herbicide options are somewhat limited. Kochia, redroot pigweed, and wild buckwheat have been the most troublesome weeds in flax. A Crisis Exemption has been issued for the use of Spartan in flax in North Dakota until May 17, 2005. The crisis exemption allows a single application of Spartan or Spartan 4F made up to 30 days prior to, or up to 3 days after planting. Spartan provides excellent control of kochia and redroot pigweed; however, only fair to good control of wild buckwheat. Spartan is able to control kochia and redroot pigweed even after emergence, apparently because of root uptake after rains have incorporated the chemical into the soil. A total post emergence program in flax has limited herbicide choices but can be effective. Flax is not competitive with weeds and because a mature flax canopy does not completely shade the ground, weeds germinating after application can reduce yields and cause harvest problems. Grass control with Poast, Select, Arrow or Prism is generally very good even on larger grasses so timing is not as critical with the available grass herbicides. When weed pressure is light, one application on 2 to 4 leaf grasses usually results in acceptable weed control. Earlier application is preferred under intense weed pressure (more than 5 wild oat or volunteer grain plants per square foot) and will increase yield compared to a later application. Broadleaf weed control is more problematic because the herbicides MCPA and bromoxynil applied alone or in combination perform best when applied to weeds smaller than one inch in height. .Bromoxynil plus MCPA does well on small weeds but gives poorer control on larger weeds and it does not control weeds that emerge after application. Spraying small weeds(less than one inch tall in two inch tall flax) will result in better weed control, less flax injury and higher flax yield than a later application to taller weeds. However, weeds like wild buckwheat, kochia and redroot pigweed can germinate and emerge after an application to 2 to 3 inch tall flax. Weed control research on volunteer canola indicates that Bromoxynil plus MCPA provides excellent control of volunteer canola when the canola is smaller than the 3 leaf stage. However, control drops significantly to fair to good when the volunteer canola reaches the 6 leaf stage. MCPA alone will also give excellent control of volunteer canola that is smaller than the 3 leaf stage. MCPA control drops off sharply once the canola reaches the 3 to 6 leaf stage and MCPA control is rated as poor. Curtail M is also labeled for flax. Curtail M will not adequately control kochia and may require a separate application for kochia control or the addition of bromoxynil at a 0.25 lb a.i. per acre to improve kochia control. Use of Bromoxynil + MCPA combinations is not necessary in combination with Curtail M as adequate MCPA is present in labeled rates of Curtail M. The table below shows current labeled herbicides in flax and approximate costs.
Johnson Approves Registration For Herbicide Agriculture Commissioner Roger Johnson has approved registration of Blanket(r) Herbicide, enabling North Dakota soybean, sunflower, field pea and chickpea producers to use the product to protect their crops from kochia and ALS-resistant kochia. "The availability of Blanket(r) should ease the shortage of sulfentrazone-based herbicides that are widely used in North Dakota to control kochia," Johnson said. Earlier this week, Johnson issued an SLN registration to DuPont for Authority(r) for sunflowers, field peas and chickpeas and a crisis exemption for Spartan(r) and Spartan(r) 4F. Both Blanket(r) and Authority(r), as well as the two Spartan(r) formulations, contain the active ingredient sulfentrazone. The product label for Blanket(r) allows preemergence applications to soybeans at a rate of 3 to 8 ounces of product per acre depending on soil type. The supplemental label for sunflowers allows preplant, preemergence, and preplant-incorporated applications with ground equipment at a rate of 2.0 to 5.3 ounces of product per acre. For field peas and chickpeas, the supplemental labeling allows fall or spring preplant, preemergence, and preplant-incorporated applications with ground equipment at a rate of 1.5 to 5.3 oz of product per acre. Sunflower, field pea and chickpea growers may not apply more than 5.3 ounces of product per 12-month period. The label also prohibits applications to be made by air or through irrigation systems. Applicators must follow all instructions, warnings and precautions on both the Section 3 label and the supplemental labeling. The supplemental labeling must be in the users' possession during application. Blanket(r) is manufactured by Tenkoz, Inc. Johnson said the availability of sulfentrazone-based herbicides is crucial to many producers, since most kochia is now resistant to previously registered herbicides. "Sulfentrazone is very effective against kochia and ALS-resistant kochia," he said. "Unfortunately, there is a shortage of Spartan(r), which until this week was the only sulfentrazone-based product labeled for sunflowers, dry peas and chickpeas." The shortage of Spartan(r) results from unexpected manufacturing delays that FMC is experiencing, as it replaces Spartan(r), a dry flowable formulation, with the liquid Spartan(r) 4F. Until now, Blanket(r) and Authority(r) had only been approved for use on soybeans. FMC recently released Tenkoz and DuPont from supply contracts, freeing the companies to label their products for other crops. Johnson commended DuPont, Tenkoz and especially FMC for their efforts in making these products available to North Dakota growers. "By working together and with the North Dakota Department of Agriculture (NDDA), these companies filled a real need for North Dakota producers," he said. "They deserve recognition for their efforts." Johnson also commended Jim Gray, NDDA's pesticide registration coordinator, for his work in obtaining the registrations and exemptions for the sulfentrazone-based products "Jim did an outstanding job of managing this complex issue," Johnson said. "His knowledge of the products, his understanding of the rules and regulations and his patience and tact in dealing with the various players resulted in growers getting the herbicides they needed." Larry Kleingartner, executive director of the National Sunflower Council, also commended Gray and NDDA in a letter to Johnson. ". . . Thanks to you and Jim for your excellent work on this very difficult subject," said Kleingartner. "My board of directors, especially those familiar with pesticide issues, opined that getting Authority(r) and Blanket(r) labels was a long shot at best, and probably not doable. Well, it is done and it is a very good feeling to know that farmers will be in compliance."
Preplant or PRE Weed Control in Pulse Crops What can we spray as a preplant burndown for the abundant winter annual populations and kochia this spring in pulse crops? Glyphosate: Glyphosate is labeled as a preplant burndown or a PRE option for control of early emerging broadleaf weeds. Higher rates of glyphosate should be considered for winter annual and kochia control. Do not add 2,4-D, Banvel, Express, or Harmony GT to the glyphosate for severe seedling injury can occur. Glyphosate can be tank mixed with most preplant herbicides such as Prowl, Sencor, or Spartan. Consult herbicide label for mixing and compatibility restrictions with glyphosate. Avoid early morning applications when temperatures are close to freezing. Glyphosate should be applied when air temperatures are above 50 F. Keep rates up when going after winter annuals such as, prickly lettuce, tansy mustard, and field pennycress. Pursuit: Pursuit is labeled as a PRE application in field pea and lentil. Field pea has good tolerance to pursuit; while lentil tolerance is marginal to good. Pursuit at 2 fl oz/acre or Pursuit DG at 0.72 oz WDG can be added to a glyphosate burndown for volunteer canola, improved mustard and winter annual control in field pea. It is recommended that the half rate of Pursuit (1fl oz/A) or Pursuit DG (0.36 oz WDG) be used in lentil. Keep in mind that user assumes all risk of crop injury. Crop injury potential increases when soils are cold that delays crop emergence. Hill-tops, low organic matter soils, or sandy/light soils have more potential for increased crop injury with lentil. Refer to label for tank-mix options, application recommendation, rate structure, and crop rotation restrictions. AIM: Aim can be added to glyphosate to improve kochia control as a burndown with pulse crops. Glyphosate is not very effective on kochia that has just emerged or that is in the Afuzzy@ stage. Aim should provide excellent control of small kochia; especially under Adroughty@ or dusty conditions. Do not expect Aim to give satisfactory control of wild mustard or volunteer canola. Seeding Rates For 2-Row And 6-Row Barley The recommended seeding rate for all barley types is 1.0 million pure live seed (PLS)/acre. For most 6-row types that equals 80 -90 lbs/acre or 1 2 bushels per acre. The biggest difference in the seeding rate is with the 2-row types. 2-row barley will often have less than 10,000 seeds per pound. This results in seeding rates of 120 - 130 lbs/acre or 2 to 2 1/4 bushels per acre to equal 1.0 M PLS/acre. Seeding Rates For Durum The recommended seeding rate fro durum is 1.5 M PLS/acre. Durum does not Astool-out@ or tiller like spring wheat or barley. Even under low plant populations, durum will not compensate with extra tillers per plant like other small grains. For medium size durum varieties (12,000 - 13,000 seeds/lb) like Lebsock, Mountrail, and Pierce that usually equates to 120 lbs/acre or 2 bushels/acre. For large seeded durum varieties (10,500 - 11,000 seeds/lb) like Ben and Maier that usually equates to 2 1/4 to 2 2 bushels per acre. Spring Wheat Seeding Rates: What Is The Rate? The common seeding rate for western North Dakota is 1.2 M PLS/A. For central and eastern North Dakota, the optimum seeding rate is 1.2 to 1.4 M PLS/acre. Some producers are looking at seeding rates as high as 1.8 to 2.0 PLS/acre. Increasing seeding rates from 1.2 - 1.4 M PLS/acre to 1.8 - 2.0 M PLS/acre has some advantages and some concerns: Advantages: 1. Decrease tillering; which results in larger seed size and higher test weight. 2. Increase main stem heads per acre; which will shorten the heading window resulting in a more consistent timing of a fungicide application for fusarium head blight control. Concerns: 1. Decreased stem strength resulting in the increased potential for lodging. A strong strawed variety should be considered if seeding 1.8 to 2.0 M PLS/acre. 2. Increase potential of leaf diseases such as, leaf rust and tan spot. No Effect: 1. Yield will be similar. 2. There will be no difference in protein percent. Frequently Asked Spartan/Prowl/Sencor Questions: 1. I applied Spartan and or Sencor as a preemergent application, how long do I have before I lose the Spartan/Sencor on the soil surface without a rain? Spartan has very low volatility. Very little (if any) product will be lost on the soil surface if rainfall is delayed. Spartan will not be activated until a significant rainfall event has occurred and some weed escapes could occur. Once activated Spartan will provide moderate residual control of many broadleaf weeds, including kochia and russian thistle. Sencor will not provide as good as residual control of weeds as Spartan. 2. My peas are just starting to emerge can I still apply Spartan? No. Spartan needs to be applied prior to the emergence of the crop. Any emerged plant tissue that comes in contact with Spartan will most likely kill the plant or severely stunt it. 3. How long do I have before I lose Prowl H20 on the surface without a rain? The new formulation for Prowl H20 has less volatility concerns than the old Prowl formulations. The concern with the new Prowl H20 is not the volatility, it’s the fact that if weeds emerge prior to the activation of the chemical, then weed control will be reduced.. Prowl does not provide A kick-back@ control of weeds, once the weeds have emerged Prowl will not control them later on. Dan Folske |
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