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Armyworms! Armyworms! Armyworms!

Armyworm Adult  Feeding Armyworm Larvae Pasture Damaged by Armyworm Larvae
Armyworm Adult
(Photo by Ralph Booker, Extension Educator, Marshall County)
Armyworm Larvae on Wheat
(Photo by Todd Hutson, Extension Educator, Fountain County)
Pasture Damaged by Armyworm Feeding (Photo by Doug Akers, Extension Educator, Boone County)
Armyworm Damage in Lawn Armyworm Larvae in Turf Closer View of Armyworm Larvae in Pasture
Armyworm Infested Turf on Right and Normal Turf on Left (Photo by Doug Akers, Extension Educator, Boone County) Closer Look at Armyworm Larvae in Turf (Photo by Doug Akers, Extension Educator, Boone County) Closer View of Armyworm Larvae in Pasture (Photo by Doug Akers, Extension Educator, Boone County)
Armyworm Larvae
Close-up of Armyworm Larvae
(Photo by Walt Sell, Extension Educator, LaPorte County)

Armyworms on the March

Tim Gibb, Extension Entomologist, Department of Entomology

Central and southern parts of the state are reporting large numbers of armyworms damaging turf areas (as well as pastures). Armyworm larvae feed on leaves and stems of turf plants much like black cutworms, but the major difference between the two pests is that the much larger concentrations of armyworms (hence the name) cause more severe damage. Control can be obtained through a number of surface insecticides. Check your label for rates and specific precautions. Only treat areas where infestations or damage is noticed, however.

Armyworm and Winter Damage in No-Mow Roughs

Zac Reicher, Assistant Professor/Turfgrass Extension Specialist, Department of Agronomy
Armyworm Damage to "No-Mow" Roughs Close-Up of Armyworm Feeding
Armyworm and Winter Damaged Fescue in "No-Mow" Roughs
(Photo by Zac Reicher)
Close-Up of Armyworm Feeding
(Photo by Zac Reicher)

A number of golf course superintendents are reporting damaged "no-mow" roughs this spring. Most of the damage occurred during the winter, but armyworms are now adding insult to injury further damaging the roughs. The photo shows both winter damage on the top of the slope and armyworm feeding at the base of the slope. Damage was sporadic and probably a number of factors were involved including an early heavy snowfall that persisted and below normal temperatures in December. Most (but not all) of the winter damage occurred in areas that didn't get mowed down prior to the heavy snowfall in early December. This suggests a smothering of the turf during the winter. In other areas that did get mowed down before winter, some smothering apparently occurred under layers of clippings. My seed company contacts tell me that pink snow mold occasionally causes widespread damage in the fine fescue seed fields in Idaho, so this may have also added to the problem. Though it was one of those bad winters when many factors stacked up against the fine fescue, I still believe it is the turf of choice for no-mow roughs. I don't expect regular winter damage in these species but to help minimize potential damage, try to mow the fine fescue down to four inches and disperse the clippings before winter.

Armyworms are continuing to feed in the tall roughs. Damage can range from light feeding on the leaves (looks like hail damage in the attached photo.) to complete severing of the stem and widespread death. If you suspect armyworm feeding, pour some disclosing solution (soapy water works well) on the area and watch for armyworms to surface. This method has been prescribed for years by our entomologist Tim Gibb. Control should only be attempted in areas where armyworms are detected and damage can be prevented. Preventative applications to areas where no armyworms can be found are not recommended. Preventative applications made now will do little to limit the next two or three generations that we expect this summer. Control can be obtained through a number of surface insecticides. Check your label for rates and specific precautions.

For more information on armyworm refer to:

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Information listed is valid only for the state of Indiana.

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Last updated: 25 June 2001/tlm.

The Plant & Pest Diagnostic Laboratory at Purdue University.