ISSUE #456

456 - Reduced Stands Increase Need For Layby Herbicides

7-6-04

Stand establishment has been a great challenge this spring. High winds, dry seedbeds, soil erosion, and frost have reduced stands in many fields. Low plant populations and uneven, gappy stands reduce sugarbeet competition with weeds. Late season weeds are likely to be a problem in many fields in 2004. Layby herbicides can provide that extra needed weed control to maximize your on-farm profitability.

Layby Herbicide Options for 2004

  • Dual Magnum
  • Treflan
  • Remember: Outlook is not labeled for use on sugarbeets in 2004.

How to Use Layby Dual Magnum

  • Apply at a rate of 1.0 pint/acre on coarse textured soils, 1.33 pints per acre on medium soils and up to 1.67 pints per acre on fine texture soils.
  • Sugarbeet plants should have four true leaves to minimize crop injury.
  • Apply layby Dual Magnum to four-leaf beets in a tank mix with the microrate.
  • Does not control emerged weeds.
  • Layby Dual Magnum will require about one-half inch of rain for activation.
  • Rainfall needed in 7-10 days to achieve good weed control.

No Liability Sign Off

Growers do not have to sign liability waiver forms to use Dual Magnum as a layby application.

How to Use Layby Treflan:

  • Apply at a rate of 1.5 pint/acre of a 4 lb/gallon formulation (0.75 lb/acre a. i.).
  • Apply when sugarbeets are two to six inches tall and well-rooted to withstand incorporation.
  • Does not control emerged weeds.
  • MUST be incorporated into the soil to avoid herbicide loss.
  • Exposed roots should be covered with soil before application. CAUTION - This could increase rhizoctonia in fields with this problem.
  • Treflan applied to the exposed crowns of plants may cause excessive girdling with an extended period of wet weather after application.

Cool Weather and Root Maggot Emergence in 2004

Colder than normal air and soil temperature conditions will cause delayed emergence of sugarbeet root maggot flies from 2003 sugarbeet fields. Sugarbeet plant growth is also delayed. Small seedlings are more vulnerable to injury from root maggot feeding. Peak fly activity will be delayed 7 to 14 days or more in 2004. Look for peak fly emergence the third week of June unless early June is very hot.

Walsh and Pembina County Situation

  • Root maggot populations are highest in the Walsh and Pembina counties, especially in the lighter soil areas.
  • A second application of granular insecticide is advised in replanted fields without a second insecticide application.
  • Activity of insecticide from very early applications may be somewhat reduced in areas with well above average rainfall.
  • Activity from less than full application rates may be inadequate for control.
  • Apply a second application of granules for maximum root maggot control.
  • Apply second granule applications about a week before anticipated peak fly activity. Just ahead of a rain is ideal.
  • Apply Lorsban 4E liquid about three days before or after peak fly activity if possible.

Grand Forks, Traill, Cass, Clay, Norman, Polk, Marshall, and Kittson Counties

  • Fields in lower risk central and southern Red River Valley counties should be adequately protected if a planting time insecticide was used.
  • Liquid insecticides may be used if an unusually high flare-up of local fly activity occurs.

Check Out the NDSU NDAWN Site Information

  • Growing Degree Day data has tracked well with microrate spray intervals so far this spring.
  • Visit the cercospora leafspot prediction site - it has been revised to provide better information in 2004.

Assistance is Available For Your Questions

  • Contact your agriculturist.
  • Contact Dr. Alan Dexter, Dr. Larry Smith, or Dr. Boetel. Phone numbers available on pages 91 to 94 of the 2004 Sugarbeet Production Guide.

Beet Seed Return Deadline

Crystal Beet Seed Customers

Remember that June 15, 2004 is the deadline for Crystal Beet Seed returns. If you are unable to meet this deadline contact your sales agent or the Beet Seed Division prior to the stated deadline. Harrows/Rotary Hoe

Remember to use harrows and rotary hoes as weed control options. Rotary hoe use is very heavy in many counties. Reference the last issue of AgNotes.