ISSUE #525

525 - Root Maggots - Latest Arrival Ever


The very cold winter and much below normal Growing Degree Days for May and June indicate a very late arrival of root maggots in 2009 beet fields. Dr. Mark Boetel, NDSU Sugarbeet Entomologist is forecasting peak fly levels may arrive the last week of June or early July. That would likely be the latest this has ever occurred. The bright side is this would allow very late planted beets to grow larger before egg laying thus minimize impact of root maggot damage.


Forecast Information Available

There are several sources of information for real time information available to growers and agriculturists to assist in implementing effective control strategies.

  • NDSU sugarbeet root maggot GDD model forecasts development.
  • NDSU monitors fly incidence and severity at 41 RRV locations every Monday, Wednesday and Friday.
  • Fly count information is posted on the American Crystal Sugar Company website three times weekly.
  • Fly counts are sent every Monday, Wednesday and Friday to all agriculturists.
  • Dr. Boetel and American Crystal Sugar Company agronomists provide forecast and control strategy information on a regular basis.
  • Timely information will be sent to growers by text message.
  • Agriculturists provide real time observations and control recommendations as needed.


2009 Root Maggot Forecast

Figure one indicates potential root maggot severity for the RRV.


Poncho-B Use High

Poncho-B seed treatment for insect control has been used on well over 50% of all acreage in 2009. Use of Poncho-B has been especially high in Walsh & Pembina counties. Poncho-B has proved to be an excellent sugarbeet insecticide in extensive NDSU research trials. However it is not a stand alone treatment in areas with severe root maggot pressure. It's absolutely necessary to use a post-emergence insecticide application along with Poncho-B if root maggot populations are moderate to severe. Poncho-B is the equivalent of about 9 lbs. of Counter for root maggot control.

Root Maggot Control Strategies

  • Carefully monitor fly populations.
  • Stay in constant contact with your agriculturist.
  • Apply a second application of granules 10-14 days before predicted peak fly occurrence.
  • Apply 1 or 2 post applications of Lorsban-4E just before and possibly just after peak fly.
  • Monitor results to fine tune strategies for 2010.

Glyphosate Resistant Weeds - Be on Guard

Dr. Jeff Stachler, NDSU Sugarbeet Weed Control Specialist has documented one case of glyphosate resistant weeds in the RRV. Grower efforts to prevent resistant weed development should include:

  • Scout early and often for survivors.
  • Alternate herbicide modes of action in a crop rotation.
  • Utilize cultural and mechanical weed control practices to achieve total weed control.
  • Maximize glyphosate activity - use right rate, right timing, right adjuvants, right gallonage.
  • Spray during favorable environments for glyphosate activity
  • Seek help from agriculturists, consultants, university experts.