ISSUE 1 May 14, 2009
SOME WEED CONTROL REMINDERS
1. With the delay in planting, winter annual weeds are growing quite well and beginning to produce seeds. Allowing winter annual weeds to produce seeds in any field, especially long-term no-tillage fields can lead to a substantial increase in the winter annual weed population in the future. Ideally, herbicides should be applied as soon as possible to reduce winter annual weed seed production. This strategy will reduce future problems. However, in fields where tillage is planned and preventative planting may be elected, this may be too expensive. For these situations, tillage or herbicide applications in the fall would be a very effective strategy to reducing future winter annual weed populations. Controlling winter annuals in the fall is the best strategy to reducing weed seed production.
2. As no-tillage corn and soybean planting is delayed, 2,4-D ester will need to be removed from the preplant herbicide application to allow for immediate planting. The removal of 2,4-D from a preplant application is not desirable, but may be a necessity to eliminate planting delays. If 2,4-D ester is removed from the preplant application, glyphosate, paraquat, or Ignite must be applied at maximum rates to maintain effective preplant activity. If dandelions are present and 2,4-D ester is not applied, apply glyphosate at a minimum of 1.5 pounds acid equivalent per acre. If annual weeds are greater than 4 inches in height, apply glyphosate at a minimum of 1.125 pounds acid equivalent per acre.
Agronomist - Weed Science
Extension Weed Specialist
GLYPHOSATE FORMULATIONS FOR ROUNDUP READY SUGARBEET
As the percentage of acreage planted to Roundup Ready sugarbeet drastically increases for the 2009 growing season in Minnesota and North Dakota, so will the availability of glyphosate products for postemergence application to Roundup Ready sugarbeet. There appears to be three groups of glyphosate formulations currently available in 2009. The three formulation groups contain 3.0, 3.7, and 4.5 pounds acid equivalent of glyphosate per gallon of product. Last year, only Roundup OriginalMAX, Roundup PowerMAX, and Roundup WeatherMAX were registered for postemergence applications to Roundup Ready sugarbeet. These products contain 4.5 pounds acid equivalent of glyphosate per gallon of product. Additional glyphosate formulations containing 4.5 pounds acid equivalent per gallon include Credit Xtreme for both states and Duplikator 5.5 Plus for Minnesota only. Apply 28 fluid ounces per acre of the 4.5 pounds acid equivalent per gallon products to obtain a rate of 0.98 pounds acid equivalent per acre. The majority of glyphosate products available for application to Roundup Ready sugarbeet in 2009 contain 3.0 pounds acid equivalent of glyphosate per gallon of product. Apply 41 fluid ounces per acre of these formulations to obtain a rate of 0.98 pounds acid equivalent per acre. The following glyphosate formulations contain 3.0 pound acid equivalent per gallon and are currently registered for postemergence application to Roundup Ready sugarbeet in Minnesota and North Dakota: Alecto 41S; Buccaneer; Buccaneer Plus; Cornerstone; Cornerstone Plus; Four Power Plus; Genesis Extra II; Glyphogan; Gly Star Original; Gly Star Plus; Grandslam 4XS; Helosate Plus; Honcho; Honcho Plus; Mad Dog; Mad Dog Plus; Makaze; Meychem 41% Glyphosate; Nufarm Credit; Nufarm Credit Extra; Strikeout Extra; and Wise Up Plus. Alecto 41 UL and Imitator Plus are only registered in Minnesota and Strikeout UL is only registered in North Dakota. The last glyphosate formulation group contains 3.7 pounds acid equivalent of glyphosate per gallon of product. These formulations include Buccaneer 5 and Extra Credit 5. For these products, apply 34 fluid ounces per acre to obtain a rate of 0.98 pounds acid equivalent per acre. Consult page 30 of the 2009 Sugarbeet Production Guide or page 89 of the 2009 North Dakota Weed Control Guide for the glyphosate product rates based upon the amount of glyphosate acid in a product and the acid equivalent rate per acre.
Read the label on the product container before application to verify that it can be applied postemergence to Roundup Ready sugarbeet. Most of the products listed above have a full Federal label allowing its application to Roundup Ready sugarbeet while some others only have a supplemental label. Not all glyphosate products contain a full load of nonionic surfactant. Consult page 89 in the 2009 North Dakota Weed Control Guide and the herbicide label to determine the need for additional nonionic surfactant based upon the glyphosate formulation being applied. Read the herbicide label to determine the correct amount of nonionic surfactant to be added. The rates range from 0.25 to 0.5 %v/v. Always add ammonium sulfate to glyphosate at a minimum of 8.5 pounds per 100 gallons of spray solution.
Agronomist - Weed Science