Description of the Pest
Western yellowstriped armyworm
Adult moths of the western yellowstriped armyworm are difficult to distinguish from other nocturnal moths. Females lay eggs in clusters covered with a gray, cottony material. Larvae measure about 1.5 inches (3.8 cm) long when fully grown. They are usually black with one prominent stripe over many narrow bright ones on each side of its body. The head is brown with a netted pattern. There is also a large black spot above the first abdominal spiracle.
Yellowstriped armyworm
Larvae of the yellowstriped armyworm are almost black, with two prominent and many fine, bright yellow stripes on the side.
Damage
Primarily foliage feeders, armyworms will also attack fruit, creating single or closely grouped circular or irregular holes on the surface. In many cases, feeding is superficial and little loss would result if not for decay organisms that enter wounds and rot fruit. Young armyworms skeletonize leaves; older larvae chew holes. Problems caused by the western yellowstriped armyworm may occur if peppers are planted near alfalfa or bean fields. The yellowstriped armyworm does not enter the fruit and infestations are most severe from July to mid-September.
Management
Yellowstriped armyworm is not a serious pest every year, but is very destructive on occasion. Armyworms tend to build up in alfalfa and weedy areas around the field and migrate from these areas when cut. Armyworms only need to be controlled if they are feeding on the crop. Keep crop residue and weeds in field and surrounding areas to a minimum to lessen the attraction of the field.
Armyworms migrating into a field can be deterred by digging a trench or by a strip treatment of an insecticideon the perimeter of the field.
Biological Control
Many natural enemies attack armyworms. Among the most common parasites are the wasps, Hyposoter exiguae and Chelonus insularis, and the tachinid fly, Lespesia archippivora. Armyworms can easily be checked for the presence of Hyposoter exiguae by pulling the larva apart and looking for the parasite larvae. Viral diseases also kill significant numbers.
Cultural Control
A deep trench can be plowed around the edges of the field with the steep side toward the peppers. This will often prevent movement of armyworm larvae into the crop.
Organically Acceptable Methods
Cultural controls and sprays of Bacillus thuringiensis or the Entrust formulation of spinosad are acceptable for use on an organically certified crop.
Monitoring and Treatment Decisions
If larvae are migrating to peppers from nearby fields and a trench can not be dug, treatment may be warranted. Treating only the field border may be effective.
Pesticides and Natural Enemy Releases
Not all registered pesticides are listed. The following are ranked by their IPM value, with the most effective and least harmful to natural enemies, honey bees, and the environment listed at the top of the table. When choosing a pesticide, consider information related to water and air quality, resistance management, and the pesticide's properties and application timing. Use PestManage to compare summarized management options for different pests in the same crop. Always carefully read the label of the product being used and take all necessary precautions when handling pesticides.
| Rank | Active ingredient | Example trade name | Group | Group Order | MoA 1 | Amount per acre | REI (hours) ‡ | PHI (days) ‡ | Comments | Selectivity 2 | Bees 3 | Predatory mites 4 | Predators 5 | Parasitoids 5 | Residue duration 6 | Leaching(fish) 7 | Adsorbed runoff(fish) 8 | Solution runoff(human) 9 | Leaching(human) 10 | Solution runoff(human) 11 | Last updated 12 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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various products # | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
11A |
Label rates | 4 | 0 | Bacillus thuringiensis preparations must... | narrow | low | low | low | short | — | — | — | — | — | 06/2016 | ||
|
|
Coragen | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
28 |
3.5–5.0 fl oz | 4 | 1 | — | narrow | — | — | — | — | — | — | — | — | — | 06/2016 | ||
|
|
Voliam Xpress | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
28/3A |
6.0–9.0 fl oz | 24 | 5 | — | — | — | — | — | — | — | — | — | — | — | — | 06/2016 | |
|
|
Voliam Flexi | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
28/4A |
4.0–7.0 oz | 12 | 1 | Review and follow the California neonico... | — | — | — | — | — | — | — | — | — | — | 06/2016 | ||
|
|
Exirel | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
28 |
7–13.5 fl oz | 12 | 1 | Highly toxic to bees; do not spray direc... | narrow | — | — | — | — | very low | very low | low | low | low | 06/2016 | ||
|
|
Verimark | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
28 |
5–10 fl oz | 4 | 1 | Highly toxic to bees; do not spray direc... | narrow | — | — | — | — | very low | very low | low | low | low | 06/2016 | ||
|
|
Avaunt | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
22A |
3.5 oz | 12 | 3 | Minimum interval between sprays is 5 day... | narrow | — | low | low | moderate | low | low | intermediate | very low | low | 06/2016 | ||
|
|
Intrepid 2F | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
18 |
Label rates | 4 | 1 | An insect growth regulator. Apply at the... | narrow | low | low | low | short | very low | low | low | very low | low | 06/2016 |
Legend
- ‡ a b Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without personal protective equipment. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of the two intervals is the minimum time that must elapse before harvest.
- # ↩ Acceptable for use on certified organic crops. Check with your certifier to confirm before application.
- 1 ↩ Group numbers for insecticides and miticides are assigned by the Insecticide Resistance Action Committee (IRAC). Insecticides with unknown modes of action are assigned mode-of-action group numbers (MoAs) that begin with UN. Rotate pesticides with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a group number of 1B; insecticides with a 1B group number should be alternated with insecticides that have a group number other than 1B.
- 2 ↩ Range of insect and mite groups affected by a pesticide. Broad means the pesticide affects most groups of insects and mites; narrow means the pesticide affects only a few specific groups.
- 3 ↩ Risk of harm to honey bees. For more information, see Bee Precaution Pesticide Ratings.
- 4 ↩ Risk of harm to predatory mites. Toxicities are generally to western predatory mite, Galendromus occidentalis. Where differences have been measured in toxicity of the pesticide-resistant strain versus the native strain, these are listed as pesticide-resistant strain or native strain.
- 5 a b Risk of harm to parasitoids and general predators. Toxicities are averages of reported effects and should be used only as a general guide. Actual toxicity of a specific insecticide depends on factors including the application rate, environmental conditions, and the life stage and species of a parasitoid or predator.
- 6 ↩ Length of time residue affects natural enemies. Short means hours to days; moderate means days to 2 weeks; and long means many weeks or months.
- 7 ↩ Risk of harm to fish from leaching, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 8 ↩ Risk of harm to fish from adsorbed runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 9 ↩ Risk of harm to fish from solution runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 10 ↩ Risk of harm to humans from leaching, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 11 ↩ Risk of harm to humans from solution runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 12 ↩ Date information was last updated in the UC IPM Pest Management Guidelines.
UC IPM Pest Management Guidelines: Peppers
UC ANR Publication 3460
E.T. Natwick (emeritus), UC Cooperative Extension Imperial County
J.T. Trumble, Entomology, UC Riverside
J.L. Aguiar, UC Cooperative Extension Riverside County
Acknowledgement for Contributions to Invertebrates
W.J. Bentley (emeritus), UC IPM and Kearney Agricultural Research and Extension Center, Parlier
W.E. Chaney (emeritus), UC Cooperative Extension Monterey County
R.L. Coviello, UC Cooperative Extension Fresno County
C.F. Fouche, UC Cooperative Extension San Joaquin County
C.G. Summers (emeritus), Entomology, UC Davis and Kearney Agricultural Research and Extension Center, Parlier
