Spray Trial - Lygus in Sugarbeets August, 2001

Ian MacRae, UMN Dept of Entomology, NWROC and Mark Boetel, Dept of Entomology, NDSU

On Sunday Aug 19, we applied a spray trial against Lygus bug on sugarbeets at the U. Minnesota Northwest Research & Outreach Center in Crookston.

Application treatments were:

  • Asana 4.0 fl.oz./ac (~1/2 label rate)
  • Asana 5.8 fl.oz./ac (low label rate)
  • Asana 9.6 fl.oz./ac (high label rate)
  • Lorsban 0.5 pt/ac (low label rate)
  • Lorsban 1.0 pt/ac (high label rate)
  • Malathion 1.5 pt/ac (low label rate)
  • Malathion 2.0 pt/ac (high label rate)
  • Untreated Control

    We evaluated low and high label rates for both chemicals. Asana was included as a benchmark, although it is imjportant to remember that Asana is NOT registered against lygus in sugarbeets. Although Asana was included in this trial, it's performance was below that of either Lorsban or Malathion. There were 4 replications of each treatment. We assessed the impact of the insecticides by calculating the percentage of the lygus population killed in each treatment (comparing pre-counts of lygus in each plot with counts taken 48 hours after treatment and calculating the percentage of lygus killed by the treatment).
    The graph below shows the results. The data indicate that Lorsban is probably the most effective insecticide to use against lygus in subargeets. It is Interesting that there was ~50% mortality shown in the control plots. We had a heavy rainfall on Friday, after the precounts and before the application and it is probable that the mortality in the control plots is associated with this weather. Heavy rain can knock insects off plants to the ground where they are exposed to greater levels of predation. Both rates of Malathion performed well, and given this products short pre-harvest interval (3 days) it may be a good fit for late season lygus control.

    PLEASE NOTE:

    Although these insecticides are registered for use in sugarbeets, none have a specific recommendation for Lygus on their sugarbeet label. This means that although it is legal to use these products in sugarbeets, there is no assumption of liability by the producer of the insecticide for failure to control Lygus. Growers choosing to use any of these products for the control of Lygus in sugarbeets, assume all risk for failure to control Lygus. It is especially important to check Malathion labels as some manufacturers have chosen not to pursue re-registration in sugarbeets. Make sure the label states the product is registered for sugarbeets or beets (a registration only for table or vegetable beets means the product is NOT registered in sugarbeets). Listing of insecticides on this page does not imply recommendation but is simply to provide options. These data come from a small plot trial (conducted within the 2001 season only), are presented for informational purposes only and should be interpreted appropriately.

    Back to Red River IPM - photos, biology and treatment information for Lygus

    Questions? Comments? E-mail us at:

    imacrae@tc.umn.edu