452 Managing Root Maggot Populations
Insect problems have not been severe in recent years in the RRV. However sugarbeet root maggots continue at high population levels in Walsh and Pembina counties. Dry conditions during the summer of 2003 and more widespread hot and dry weather in 2004 could see root maggot populations begin to rebound. Traditional areas with high populations of root maggots in 1988-1992 included the vicinity of Minto, Crookston, Climax, Oslo, north and east of Hillsboro and near Glyndon and Sabin in the Moorhead district. Townships along Minnesota Highway 9 in Clay, Norman and Polk counties had significant sugarbeet root maggot populations on light soils.
The map in Figure 1 shows anticipated population levels for 2004.
Planting Time Management Considerations:
- Application equipment calibration is essential
- Saves over application cost
- Ensures effective rates applied
- Reduces crop injury risk
- Choose a product and rate effective for local root maggot populations
- Wind screen use keeps insecticide on target area
- Check all hoses/tubes for obstructions
- Achieve even granule flow over the row
- Soil insecticide incorporation is recommended
Spoon is Best Insecticide Placement Method:
Results of extensive insecticide placement method trials were presented at MBA seminars by NDSU Entomologist, Dr. Mark Boetel. The spoon placement methods performed best with Counter and Lorsban, while Temik gave best sugarbeet root maggot control when applied as a modified in-furrow (MIF) application, see Figure 2. The spoon was evaluated with a bolt positioned in the very center to reduce the insecticide rate falling into the seed furrow. This will minimize any chance of phytotoxicity that might reduce germination or seedling emergence
- Spoon placement increased revenue per acre $35-70 with Counter and Lorsban
- MIF applications more effective with Temik
- Banding was not as consistent as other placement methods
- Never apply Lorsban as a MIF application
Re-seeding Sugarbeet Fields
When re-seeding a field a different insecticide from that used at first planting must be used to comply with EPA labels.
Mustang MAX and Sugarbeet Root Maggot Control:
The NDSU sugarbeet entomology project has extensively evaluated Mustang or Mustang MAX for sugarbeet root maggot control for about 4 years.
The New Mustang MAX label does not list root maggot as an insect controlled. It's not that effective for larvae or adult flies.
Mustang MAX will not hold up under moderate to high root maggot populations, Figure 3.
How Should Mustang MAX Be Used?
- It's very effective for wireworm control
- It can be applied as a T-band or in-furrow
- Mustang MAX is compatible with starter fertilizer
- Mustang MAX plus starter fertilizer gives very good springtail and wireworm control
Sources of More Information
- 2004 Pocket Guide
- 2004 Research Report Pages 176-219
- 2004 MN & ND Extension Insect Control Guides
- 2004 MBA Handouts
A special thanks to Dr. Mark Boetel, NDSU Entomologist for use of data and pictures in this issue of the Ag Notes.