ISSUE #524

524 - Weed Control Easier - Pitfalls Remain

5-22-09

The acreage planted to Roundup Ready® sugarbeets in 2009 will exceed 90%. Use of glyphosate resistant beets certainly makes many aspects of weed control in sugarbeets much easier. Delayed planting of all crops this spring will result in need to control weeds in all crops simultaneously increasing demands on grower's time. Many sugarbeet fields were not sprayed on time in 2008 resulting in yield loss due to crop competition.

Avoid Competition with Proper Timing

Weed PressureRecommended Timing
Light 2-4 leaf beets
Moderate 2 leaf beets
Heavy Cotyledon - 2 leaf beets

524

Roundup Rate Selection

One rate of glyphosate does not fit all situations. Select rates based on a number of factors including the following considerations:

  • Weed species present
  • Environmental conditions
  • Weed growth stage
  • Possible weed tolerance or resistance to glyphosate
SituationRate (4.5 lb/Gal Acid Equiv)
Small weeds, very favorable environment 22 oz/acre
Less favorable environment or larger weeds 28 oz/acre
Unfavorable environment, very large weeds, hard to control weed species, suspected tolerance to glyphosate 32 oz/acre

Timing the Second Application

  • The label states it must be 10 days or more after the first application
  • Determine if sufficient weeds have emerged
  • Determine when weed size and density justify spraying
  • Most second applications will be from 14 to 28 days after the initial application

Tips on Maximizing Weed Control with Roundup

  • Weed control is best between 10 a.m. and 4 p.m.
  • Add 8.5 to 17 lbs of AMS per 100 gallons of spray solution.
  • Weed control is often better with spray volumes at the low end of the range.
  • Rain within 6 hours after application may reduce weed control.
  • Avoid spraying with dust on plants.
  • Avoid spraying with dew on plants.
  • Cool weather slows activity and time needed to kill weeds.
  • Frost before application will reduce control.
  • Drought slows weed growth, reduces Roundup activity.
  • Delay cultivation at least 3 days after Roundup use to maximize control.
  • Air temperature over 85 F during application can reduce weed control.
  • Don't spray after sunset-weed control can be reduced.

Generic Glyphosate Use

Growers can legally use any generic glyphosate product labeled specifically for post emergence use on sugarbeets. If a generic glyphosate is used a grower will no longer qualify for Monsanto's reward program for other Roundup Ready® crops. Be sure to select generic rates carefully. The acid equivalent content can vary from 3.0 to 4.5 lb/gallon.

Dr. Jeff Stachler, NDSU/UM Sugarbeet Weed Specialist has identified the following generic products labeled for sugarbeet.

3.0 Acid Equivalent3.7 Lbs Acid Equivalent4.5 Lbs Acid Equivalent
Alecto 41S Bucaneer
Bucaneer Plus
Cornerstone
Cornerstone Plus
Genesis Extra II
Glyphogan
Gly Star Original
Gly Star Plus
Grand Slam 4X5
Helosate Plus
Imitator Plus (MN only)
Honcho
Honcho Plus
Mad Dog
Mad Dog Plus
Makaze
Meychem 41% Glyphosate
Nufarm Credit
Nufarm Credit Extra
Strikeout Extra
Wise Up Plus
Alecto 41 UL (MN only)
Strikeout UL (ND only)
Four Power Plus
Bucaneer 5
Extra Credit 5
Credit Extreme
Duplikator 5.5 Plus (MN only)

Replant and Tech Fees

If replanting occurs contact the seed dealer that supplied the original seed to properly handle any technology fee rebates that might be necessary.

Springtails and Wireworms

Springtail and wireworm infestations have been identified in the RRV. Poncho Beta has proven effective in NDSU trials against these pests.