Sunflower XIV-1

Pale Western Cutworm

Frank B. Peairs


Cutworm Adult	Cutworm Larva

Identification (and life cycle/seasonal history)

The pale western cutworm is a subterranean soft bodied caterpillar; grayish-white in color, unmarked by spots or stripes, with two distinct vertical brown bars on the front of the head capsule. A fully developed larvae is about 25 millimeters (one inch) in length.

Adult moths emerge from the soil in late summer and fall. Eggs are deposited in loose soil and usually hatch within two weeks. Hatch may be delayed for up to several months if moisture and temperature conditions are unfavorable. Larvae prefer loose, sandy or dusty soil and are found most easily in the driest parts of the field, such as hilltops.

Outbreaks are associated with dry conditions in the previous spring. If the preceding May and June had fewer than 10 days with ? inch or more of rainfall, then pale western cutworm populations can be expected to increase. If the preceding May and June had more than 15 such days the cutworm will almost totally disappear. Rainfall events of more than ? inch tend to drive the cutworms to the soil surface and exposes them to more than usual levels of predation and parasitization.

Plant Response and Damage

Pale western cutworm is a subterranean cutworm feeding on stems at the crown. After feeding is completed, pale western cutworm larvae move to pupal chambers constructed several inches below the soil surface. Adult emergence can begin in late July. Small grains, corn, and a variety of other crops have been damaged by pale western cutworm.

Management Approaches

Chemical Control

Check fields early and control if there is one cutworm per square foot or if stands are reaching the lower limit for optimum plant populations. Treatment may not be necessary if most larvae are fully grown (1 to 1? inches) and therefore close to the end of their feeding period.

Product list for Pale Western Cutworm:
Pesticide	Product/Acre (Fl oz. or oz. product)	Preharvest Interval, remarks
Asana XL^R^,1	5.8 - 9.6	28 days. Do not feed forage or fodder tolivestock. Extremely Hazardous to Bees!
Baythroid XL^R^,1	0.8 - 1.6	30 days. Extremely Hazardous to Bees!
carbaryl¹^,2	See labels	60 days. 30 days to graze or forage. Extremely Hazardous to Bees!
chlorpyrifos 4E^R1,2	32 - 48	42 days. Do not graze. Up to 2 lb preplant. Up to 4.5 lb total AI/yr. Extremely Hazardous to Bees!
Delta Gold^R^,1	1.0 ? 1.5	21 days to harvest. Do not apply more than 0.045 lb ai/acre/crop.? Do not graze or feed treated forage to livestock. Extremely Hazardous to Bees!
lambda cyhalothrin^R1,2	1.92 ? 3.20	45 days. Do not exceed 0.12 lb total AI/yr. Extremely Hazardous to Bees!
Proaxis^R^,1	1.92 ? 3.20	45 days. Do not exceed 0.06 lb total AI/yr. Extremely Hazardous to Bees!
^RRestricted use pesticide. ¹Labeled for chemigation. ²Generic active ingredient, may be additional formulations.
The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.

Categories: Sunflower, Insects, pale western cutworm

Date: 5/17/2007