New!!

Current mapping of Sugarbeet Root Maggot Populations in the Red River Valley!!
Early Season Scouting for Soybean Aphids

July, 2002 - Armyworms in Small Grinas

There have been reports of armyworms in small grains. Plots on the Research & Outreach Center in Crookston yielded small, 1st instar larvae. The caterpillars were very small (1/8") and obviously just hatched in the last day or two. There was no feeding as of yet so no frass pellets were on the ground. The larvae themselves were on the plant but very difficult to see. We would not have normally have noticed them but were using sweep nets which do a good job of recovering larvae at this stage (later larvae will have to be scouted using traditional methods).

Populations were not yet heavy enough for insecticide application to be economical. Also, the early stage of the larvae recovered leads me to suspect we may see more over the next 2 weeks. Be aware, applying too early may result in the necessity of re-application. Scout fields to determine if treatment is warranted.

Armyworms do not overwinter here in northern Minnesota, our populations arise from adults blown in on southerly storm fronts in late spring and early summer. The earlier the growing season, the earlier it is necessary to scout armyworms. These insects are dark green to light brown and have a light stripe down the center of their back. Adults lay eggs in grassy or weedy areas or in lodged grain. Armyworms, like some cutworms, tend to feed at night and hide throughout the day. If feeding damage is found in the foliage and no other responsible insects pest can be found, scout for armyworms by parting foliage on the plant and inspecting the plant and the soil below for small fecal pellets. If pellets are found (or if no other causative agent for plant damage can be found) then look for larvae under plant trash, soil clods, or in soil cracks. If 4-5 worms or more are found per sq. foot, treatment is recommended. Because populations are higher in lodged areas, be sure to average the population over the entire field.

Foliar applications labled for treating armyworms in small grains include:

Insecticide	Rate	NOTES
Ethyl parathion 8EC*	0.25 pt/ac	15 d PHI, up to 3rd instar
Lannate LV*	0.75 - 1.5 pt/ac	7d PHI, 48h REI
Lorsban 4E-SG*	1 pt/acre	28D PHI
Penncap-M*	2-3 pts/ac	15d PHI
Warrior*	2.56-3.84 fl.oz/ac	30D PHI, do not apply more than 0.48 pts/A per season
Malathion 8EC*	1-1.25 pts/ac	7D PHI

*Restricted Use Pesticide
Always read and follow label instructions.

Sleceted Past IPM Updates

June 20, 1999 - Potato Leafhopper, Grasshoppers, Cereal Insects
Sept 12, 1999 - Impact of Aster Yellows on Canola May be Greater Than You Think
Aug 31, 1998 - Lygus in Sugarbeets
July/Aug, 2000 - Armyworm Outbreak in RRV
Fall, 2000 - Soybean Aphid, A New Insect Pest in Minnesota Soybeans
Fall, 2001 - Soybean Aphid in NW Minnesota
August, 2001 - Lygus in Sugarbeets
May 2002 - Cutworms in Sugarbeets

Publications Available for Download

Insects

Grasshoppers -
Minnesota Grasshopper Management - 2002 with color graphics
Minnesota Grasshopper Management Brochure with scouting and control information (available as a PDF file designed to be a tri-fold brochure).

Scouting -
Scouting for Insects in Wheat, Alfalfa, and Soybeans - a manual prepared for the University of Minnesota Extension Service Field School, held at the Northwest Experiment Station, Crookston, MN, July 7-8, 1998.
Early Season Scouting for Soybean Aphids - A guide to scouting early season soybeans for soybean aphid.

Questions? Comments? E-mail us at:

imacrae@tc.umn.edu