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ISSUE 1    May 4, 2006

CUTWORMS EMERGE AS AN EARLY SEASON INSECT PROBLEM

Cutworms have already been reported damaging winter wheat in southwestern ND (D. Barondeau). In this situation, cutworm injury was very severe and the producer was forced to replant the field to spring wheat using an insecticide. As soil temperatures continue warm above 40 F, cutworms will become more active.

Typical feeding injury symptoms include clipped off plants with the larvae (caterpillars) underneath in the soil, or bare patches of ground in localized spots in a field. Cutworm feeding activity usually extends from May through the end of June and young emerging plants are the most susceptible stage of crop development. Early season (May) cutworms overwinter as partially mature larvae. Examples are the dingy cutworm and pale western cutworm. Eggs of the dingy cutworm are laid on the face of sunflowers the previous year. So, last year’s sunflower fields are at the greatest risk to injury by dingy cutworms. Late season (late May – June) cutworms overwinter as eggs or young larvae, and include the red-backed cutworm and darksided cutworms.

The key to successful cutworm control is early detection and knowing your plant population, especially in corn, dry beans, sunflowers, soybeans, sugarbeets, and alfalfa. Knowing your plant stand population can help determine the importance of whether to spray for cutworms along with the treatment threshold. For example, if the plant stand count is below the recommended plant populations, few or no plants can be loss to cutworm feeding. In contrast, if plant stand counts are at the recommended plant population, cutworm populations that are below the treatment threshold level could be tolerated without economic yield loss. When spraying insecticides for cutworm control, applications should be made in the evening when cutworms are active. Wet soil conditions will also improve insecticide efficacy, as cutworm fed near the soil surface in these conditions.

Treatment thresholds for cutworms by crop are:

Canola – 1 per square foot
Small grain – 4 to 5 cutworms per square foot
Corn – 3 to 6% of the plants cut and small larvae less than ¾ inch present
Sugarbeets – 4 to 5% of plants cut
Soybeans / Dry beans – 1 or more larvae per three feet of row or 20% of plants cut
Sunflower – 1 per square foot or 25-30% of plants cut
Alfalfa – 4 to 5 or more per square foot (new stands – only 2/sq ft)

Insecticides labeled for cutworm control in ND include:

Insecticide
(Active Ingredient)

Canola

Wheat

Corn

Sugarbeets

Soybeans

Dry Beans

Sunflower

Alfalfa

Asana (esfenvalerate)

X

X

X

X

X

Baythroid 2 (cyfluthrin)

 

X

   

X

X

X

X

Capture (bifenthrin)

X

 

X

   

X

   

Decis (deltamethrin)

X

 

X

 

X

 

X

 

Lannate LV(methomyl)

   

X

X

 

X

 

X

Lorsban (chlorpyrifos)

 

X

X

X

X

 

X

X

Methyl parathion

X

   

X

     

X

Mustang Max (zeta-cypermethrin)

 

X

X

X

X

X

 

X

Nufos 4E (chlorpyrifos)

Orthene (acephate)

X

Permethrin

   

X

 

X

   

X

Proaxis (gamma-cyhalothrin)

X

X

X

 

X

X

X

X

Sevin (carbamate)

   

X

X

X

X

X

X

Sniper (bifenthrin)

X

 

X

         

Taiga Z (lambda-cyhalothrin)

X

X

X

X

X

X

Warhawk (chlorpyrifos)

 

X

X

X

   

X

X

Warrior (lambda-cyhalothrin)

X

X

X

 

X

 

X

X

Yuma (chlorpyrifos)

 

X

X

X

X

 

X

X

Note: Mention of an insecticide does not constitute an endorsement or recommendation of the insecticide. Please consult the 2006 ND Field Crop Insect Management Guide for rates: http://www.ext.nodak.edu/extpubs/plantsci/pests/e1143w1.htm

Insecticide seed treatment products, like Cruiser (a.i. thiamethoxam), Gaucho (a.i. imidacloprid), or Poncho (a.i. clothianidin) are only labeled for suppression of cutworms, not complete control of cutworms. However, insecticide seed treatments are very effective in controlling other early season insect pests, like wireworms and seed corn maggots.

 

INSECTICIDE UPDATES FOR NORTH DAKOTA

Section 2ee Granted for Control of Sunflower Beetle and Red Sunflower Seed Weevil with Warrior with Zeon Technology, Syngenta Crop Protection
This new formulation of Warrior is a water-based insecticide and safer for pesticide applicators. It has the same active ingredient, lambda-cyhalothrin, as the old formulations of Warrior T. Application rates for control of sunflower beetles are 1.28 to 2.56 fl oz / A, and for red sunflower seed weevil are 1.92-3.84 fl oz / A. These rates are slightly reduced over the old formulation of Warrior. Other crops that have the "Warrior with Zeon Technology" label besides sunflower include: alfalfa, canola, field corn, wheat, soybeans, field beans, field peas, chickpeas and lentils.

Furadan Undergoes Reregistration Eligibility Decision (RED)
Furadan (carbamate class of insecticide) is undergoing a RED process by the US Environmental Protection Agency (EPA). As part of the process, EPA seeks comments on risks, benefits and effectiveness of Furadan. In North Dakota, furadan is registered for control of many insect pests on wheat, barley, oats, alfalfa, potato, soybean and sunflower. If you would like to comment on furadan, please go to the following website before mid-May: http://www.furadanreg.com/.

 

NOTES ON FIELD OBSERVATIONS OF EARLY SEASON INSECT PESTS

Crucifer flea beetles have been observed in overwintering sites (shelterbelts/grassy areas) and in last year’s canola fields feeding on volunteer canola and wild mustard. As temperatures increase above 58 F, early emerging canola fields should be scouted to ensure that the insecticide seed treatments are effective in minimizing flea beetle feeding injury. Flea beetles prefer calm winds and warm, sunny days for feeding and moving into spring-planted canola fields.

In mid April, soybean aphids hatched from eggs that were laid on buckthorn, its overwintering host, in the Red River Valley. Fortunately, the Multi-colored Asian ladybird beetle, a beneficial predator, was also observed feeding on eggs and adult aphids.

Janet Knodel
Extension Entomologist
jknodel@ndsuext.nodak.edu


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