New!!


Current mapping of Sugarbeet Root Maggot Populations in the Red River Valley!!

Early Season Scouting for Soybean Aphids

July, 2002 - Grasshoppers in The Red River Valley

There are isolated hot-spots of grasshoppers in NW Minnesota and the Red River Valley. This is surprising given the amount of precipitation lately. Currently, populations are approaching thresholds (see table below) in small grain fields and populations seem to be rising in soybeans. Most of these grasshoppers appear to be 1st or 2nd instars (very young nymphs), there are relatively few adults in these populations.

Grasshoppers are usually controlled by fungal diseases that impact newly hatching nymphs in the early summer. It may be that the high temperatures have made these fungal disease less effective, or that the wet soil delayed hatching of the eggs until now. Because small grains are maturing and CRP is starting to be hayed, young grasshoppers may move from these systems to neighboring crops. Keep an eye on sugarbeets, soybeans, drybeans and alfalfa in the near future.

Scout for grasshoppers on field edges first, thresholds are in the table below. For more in depth information, see the Grasshopper Management –2002 bulletin at:

http://nwroc.umn.edu/ent/gh98/hopper1.html

Table 1. Grasshopper action thresholds

Rating

Nymphs per square yard

Adults per square yard

Margin

Within Field

Margin

Within Field

Light

25-35

15-25

10-20

3-7

Threatening

50-75

30-45

21-40

8-14

Severe

100-150

60-90

41-80

15-28

Very Severe

200+

120+

80+

29+

Treatment is advised when populations reach the "Threatening" level. Some registered pesticides are in the table below.

Table 2. Insecticides registered in Minnesota for use against grasshoppers. Always check the label for the most current registration information.

Crop

Product

Rate/Acre

Alfalfa

Baythroid 2*
Dimethoate 4EC
Furadan 4F*
Lorsban 4E*
Malathion 8EC
Mustang*
Warrior

2.8 fl.oz
1.5-2.0 pt.
0.25-0.5 pt.
0.5-1.0 pt.
1.0-1.5 pts.
3.0 - 4.3 fl.oz.
2.56-3.84 fl.oz.

Corn

Asana XL* **
Dimethoate 4EC* (field corn) Furadan 4F* (field corn)
Lorsban 4E*
Malathion 8EC (early instars)
Penncap M*
Mustang*
Mustang*
Warrior

5.8-9.6 fl.oz.
1 pt
0.25-0.5 pts
0.5-1.0 pts
1.5 pts.
2.0-3.0 pts
3.0-4.3 fl.oz (sweet)
2.9-4.3 fl.oz. (field)
2.56-3.84 fl.oz.

Dry Bean

Asana XL* **
Dimethoate 4E
Penncap M*
Mustang

5.8-9.6 fl.oz.
0.5-1 pt.
2.0-4.0
3.4-4.3 fl.oz.

Soybeans

Asana XL* **
Dimethoate 4EC
Furadan 4F*
Lorsban 4E*
Penncap M*

Mustang*
Warrior*

5.8-9.6 fl.oz.
1.0 pt.
0.25-0.5 pt.
0.5-1.0 pt.
2.0-3.0 pt. (higher rate if cold or grasshoppers are large
3.4-4.3 fl.oz.
3.20-3.84 fl.oz.

Sugarbeet

 Asana XL* **
Mustang*
Lorsban 4E*

5.8-9.6 fl.oz.
2.4-4.3 fl.oz.
0.5-1 pt.

Sunflower

Asana XL* **
Baythroid 2*
Furadan 4F*
Lorsban 4E*
Warrior*

5.8-9.6 fl.oz.
2.0-2.8 fl.oz.
0.25-1.0 pt./1000 row ft
1.0 pt.
2.56-3.84 fl.oz.

Wheat

 Dimethoate 4E
Furadan 4F*
Lorsban 4E-SG*
Malathion 8EC
Penncap M*
Mustang*
Warrior*

0.75 pt.
0.25-0.5 pt
0.5-1.0 pt.
1.0-1.25 pts.
2.0-3.0 pts.
1.0-1.5 qts.
2.56-3.84 fl.oz.

Pasture (&CRP)

Malathion 57EC / 8EC

Check Labels

Roadside / Non Cropland

Diazinon AG500*
Asana XL
Diazinon AG500

Check Labels

* Restricted use pesticide
** Asana XL has a reduced rate label for early (1st & 2nd) instar grasshopper nymphs in some crops and states - check the label.
ALWAYS check the label for the most recent registration information!!

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
July 2002 - Armyworms in Small Grains

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