| FOR IMMEDIATE RELEASE | CONTACT:Dan Sullivan |
| May 14, 2004 | (406) 444-LAST FOUR DIGITS
TTY (406) 444-5400 |
Grasshopper Threat to Crops Depends on Weather
HELENA, Mont. — A dry fall and winter is likely to result in a bumper crop of grasshoppers in portions of Montana. Now may be the best time to begin scouting crops and rangeland that borders irrigated cropland.
For a second season, the Montana Department of Agriculture has received a Section 18 emergency exemption that provides an additional tool, Dimilin 2L insecticide, to control grasshoppers in wheat and barley crops, says Ralph Peck, director of the Montana Department of Agriculture.
Early field scouting is important because Dimilin 2L works best when grasshoppers are small, between the second and fourth nymph stages of development or when the hoppers measure from one-half to three-fourths of an inch in length, says Patricia Denke, entomologist with the Montana Department of Agriculture.
Federal surveys in late 2003 found grasshopper hot spots in Glacier, Toole, Pondera and Sanders counties in northwestern Montana, as well as in a band from west of Lewistown to south of Livingston. Other areas with elevated grasshopper populations were scattered throughout western and central Montana.
Grasshoppers and Mormon crickets tend to migrate to green fields as range grasses dry and mature crops are harvested, Denke says. In drought-stricken areas with irrigated crops it is particularly important to scout field borders as grasslands become less palatable to the insects.
Treating field borders where grasshopper concentrations are higher may be more cost effective than treating entire fields. In rangeland, a method of strip treatment pioneered in Wyoming, known as Reduced Agent/Area Treatment or RAAT, also can be more economical.
Product options depend on the crop involved. County Extension Service agents and chemical applicators and retailers can advise growers on the best treatment for their particular situation.
Information on scouting fields for grasshoppers and on life cycles and treatment thresholds are available from a University of Wyoming site at: http://www.sdvc.uwyo.edu/grasshopper. For additional information on Montana grasshoppers and treatment options, contact Patricia Denke at (406) 444-3730 or by email at agr@mt.gov.
