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Helmuth Rogg, Oregon Department of Agriculture, La Grande, OR
541-963-4608, hrogg@oda.state.or.us
Gary Brown, USDA-APHIS Portland, OR
503-326-2814 (ext. 239), Gary.W.Brown@aphis.usda.gov
La Grande, September 23, 2007
The 2007 Oregon grasshopper survey season, conducted by ODA in cooperation with USDA APHIS PPQ, started on May 15 and ended on September 6. Adult survey data recorded economic levels of 8 grasshoppers per square yard and higher on 798,358 acres (2005: 64,751 acres, 2006: 97,399 acres) in 13 (2005: 9, 2006: 14) counties of eastern Oregon. In 2007, a total of 1585 (2005: 859 and 2006: 1368) sites were visited of which 706 were nymphal and 870 adult survey sites.
The counties with the highest infestation levels were Baker with 335,589 acres, Union with 154,170 acres, Wallowa with 83,603 acres, Grant with 76,667 acres, Wheeler with 55,142 acres, Malheur with 40,736 acres, Umatilla with 31,324 acres, Jefferson with 7,185 acres, Morrow with 4,610 acres, and Gilliam with 5,186 acres. Areas with significant infestations of more than 10,000 acres were located around Haines (319,000 acres) in Baker County, Elgin (117,300 acres), La Grande (10,070 acres), Union (12,230 acres), and Medical Springs (14,570 acres) in Union County, Enterprise (25,840 acres), Imnaha (17,280 acres), and Elk Mountains (17,710 acres) in Wallowa County, Flowers Gulch (68,870 acres) in Grant County, Fossil South/Salmon Fork (48,710 acres) in Wheeler County, Moores Hollow (23,600 acres), Clevenger Butte (10,240 acres) in Malheur County, and Echo (11,880 acres) in Umatilla County.
Like in recent years, infestations in the Klamath Marsh National Wildlife Refuge, Klamath County, were again relatively low. Although the traditional Camnula egg bed areas at Sagebrush Point and at the Lane Ranch were not flooded like in 2006, only a few egg beds showed economic infestations. At the end of May, intensive nymphal surveys were conducted also including adjacent private rangeland. Following a public information meeting, 17 acres of Camnula pellucida egg beds were treated with Dimilin applying 50% RAATs for ATV, protecting 34 acres. Post treatment counts showed an average of 94% control. Adult surveys at the end of August did not show any economic levels in the Klamath marsh and adjacent private rangeland.
Following last year’s grasshopper treatment program on more than 20,000 acres of private rangeland in the Fort Klamath area, Klamath County, no grasshopper activity was recorded this year on treated areas. However, economic infestation of Camnula pellucida were recorded on about 1,724 acres of non treated areas.
This year has seen a large buildup of grasshoppers in Northeastern Oregon. At the beginning of June, 2007 high numbers of grasshoppers were reported in the Haines area. Surveys recorded economic infestations of grasshoppers, predominately Camnula pellucida, stretching from Elgin in Union County, Enterprise in Wallowa County to Baker City in Baker County. Almost 600,000 acres of mostly private rangeland were infested with up to 74 grasshoppers per square yard! (map 2)
In Haines, Baker County, ODA provided technical assistance to a private rancher against a grasshopper outbreak of Melanoplus bivitattus and Camnula pellucida on about 176 acres of rangeland in June. The landowner chose to apply Malathion ULV by ground. However, the fields were re-infested later in the summer by predominately Camnula pellucida from neighboring non-treated fields.
The last major grasshopper outbreak in Baker County was in 1986. Records of historical outbreaks date back to 1954 when more than 15,000 acres south of Halfway were heavily infested with grasshoppers. In that same year, over 4,000 acres were infested northeast of Enterprise in Wallowa County. Grasshopper outbreaks on range and cropland in Wallowa, Union and Baker counties were treated with aerial applications of Malathion in 1969, 1972, 1974, 1979, 1980, 1985 and 1986 totaling more than 632,000 acres (map 3).
Adult grasshopper survey in other areas of eastern Oregon showed economic levels in Gilliam, Grant, Jefferson, Klamath, Malheur, Morrow, Umatilla, and Wheeler counties. Most infestations were observed on private rangeland with levels ranging between 8 and 50 grasshoppers per square yard. The dominant species in these counties were Melanoplus femurrubrum, M. sanguinipes, M. packardii, Oedaleonotus enigma and Aulocara elliotti.
Mormon crickets, Anabrus simplex, were recorded in areas south of Arlington (5,359 acres), Gilliam County, for the third year in row, and also near Jordan Valley (3,935 acres), and Jackson Summit (2,267 acres) in Malheur County. Landowners in Jordan Valley using Carbaryl bait conducted treatment against Mormon cricket. A large area of Mormon crickets on BLM land in nearby Owyhee County, Idaho, was successfully treated with Dimilin by APHIS’ Idaho Office this year.
Table 1 (pdf, 240 KB) - (also see accompanying maps) represents an estimate of the acreages with economic levels of grasshopper infestations (>8 grasshoppers per square yard) based on the 2007 adult survey results. We cannot accurately predict where grasshopper outbreaks will occur because they depend greatly on climatic conditions at the time of hatch and early development, variables that cannot be accurately predicted. However, the areas of economic grasshoppers in 2007 serve as indicators of potential problem areas for 2008, and should be closely monitored in early spring of 2008.
Table 2 (pdf, 79 KB)- Oregon Grasshopper Survey Statistics 2005-2007
Statewide 2007 survey map
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