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Helmuth Rogg, Oregon Department of Agriculture, Salem, OR
503-986-4662, hrogg@oda.state.or.us
Gary Brown, USDA-APHIS Portland, OR
503-326-2814 (ext. 239), Gary.W.Brown@aphis.usda.gov
Salem, September 28, 2008
The 2008 Oregon grasshopper survey season, conducted by ODA in cooperation with USDA APHIS PPQ, started on May 19 and ended on August 29. Adult survey data recorded economic levels of 8 grasshoppers per square yard and higher on 1,129,820 acres (2005: 64,751 acres, 2006: 97,399 acres, 2007: 798,358 acres) in 12 (2005: 9, 2006: 14; 2007: 13) counties of eastern Oregon. In 2008, a total of 2722 (2005: 859 and 2006: 1368; 2007: 1585) sites were visited of which 1116 were nymphal and 1606 adult survey sites.
The counties with the highest infestation levels were Baker with 677,404 acres, Malheur with 150,671 acres, Union with 96,543 acres, Wallowa with 62,069 acres, Grant with 50,792 acres, Umatilla with 16,802 acres, Jefferson with 11,176 acres, Klamath with 9,796 acres, Lake with 9,314 acres, Morrow with 3,866 acres, Wheeler with 3,619 acres, and Multnomah with 2,973 acres.
Areas with significant infestations of more than 10,000 acres were located around Haines (232,716 acres), Gold Hill (229,514 acres), Salt Creek (112,957 acres), Dry Gulch (82,444 acres), and Pine (18,394 acres) in Baker County, around Ritter (45,607 acres) in Grant County, around Boswell Spring (49,453 acres), Pine Tree Ridge (41,366 acres), Lower Mud Spring (21,576 acres), and Mud Spring (11,912 acres) in Malheur County, around Lena (34,080 acres) in Morrow County, around North Powder (41,211 acres), Thief Valley (22,576 acres), Partridge Creek (11,170 acres), and Highline Canal (10,489 acres) in Union County, and around Box Canyon (16,169 acres), and Flora (12,616 acres) in Wallowa County.
Like in recent years, grasshopper infestations in the Klamath Marsh National Wildlife Refuge, Klamath County, were again relatively low. Adult surveys at the beginning of August did not show any economic levels in the Klamath marsh, except for the “Buckpasture” area where Camnula were recorded with more than 24 per square yard on 113 acres.
Surveys of the 2006-treated Fort Klamath area did not show any grasshopper activity this year.
The outbreak in Northeastern Oregon continued this year. In 2007 almost 600,000 acres in Baker, Union and Wallowa counties were recorded with economic infestations of up to 74 grasshoppers per square yard. This year Baker County alone recorded almost 680,000 acres. The grasshopper densities reached highs of up to 200+ grasshoppers per square yard in several locations. An intensive survey was implemented to record the extent of infestation in the area.
In preparation for a potential outbreak in northeastern Oregon, a grasshopper IPM workshop was held on April 25 in Baker City with specific information on the clearwinged grasshopper. The workshop was presented by Alex Latchininsky and Scott Schell from the University of Wyoming Extension Service and organized by USDA-APHIS-PPQ, ODA and OSU Extension Service. In total, 24 participants attended the workshop.
In addition, a growers and ranchers meeting was held at the OSU Extension Service office in Baker City on Tuesday, June 24. More than 30 participants listened to recommendations on how to treat economic grasshopper levels in their rangeland and wheat and alfalfa fields. A commercial pesticide applicator participated as well.
Oregon Department of Agriculture requested from EPA a crisis Section 18 exemption for Dimilin application in alfalfa for the growers in Baker County.
In the Haines area, Baker County, ODA and OSU Extension Service provided technical assistance to private ranchers in their efforts to suppress the grasshopper outbreak of predominately Camnula pellucida on about 15,000 acres of range and cropland in June. The landowners chose to apply Dimilin, Mustang Max, Malathion, Warrior and Carbaryl by ground and air with a total cost of almost $180,000.
On Wednesday, June 25, Dimilin was applied by ATV on 150.4 acres of BLM land south of a private property in Sparta, Baker County. Comparison between pre and post-treatment counts accounts to an 83 to 86% control.
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 (see attached map 3).
Adult grasshopper survey in other areas of eastern Oregon showed economic levels in Grant, Jefferson, Klamath, Lake, Malheur, Morrow, Umatilla, Union, and Wheeler counties. Most infestations were observed on private rangeland with levels ranging between 8 and 200 grasshoppers per square yard. The dominant species in these counties were Camnula pellucida, Melanoplus femurrubrum, M. sanguinipes, M. packardii, Oedaleonotus enigma and Aulocara elliotti.
Mormon crickets, Anabrus simplex, were recorded in the area south of Arlington, Gilliam County, for the fourth year in row, however in non-economic levels.
Table 1 (pdf, 66 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 2008 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 2008 serve as indicators of potential problem areas for 2009, and should be closely monitored in early spring of 2009.
Table 2 (pdf, 22 KB)- Oregon Grasshopper Survey Statistics 2005-2008
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