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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, October 30, 2009
The 2009 Oregon grasshopper survey season, conducted by ODA in cooperation with USDA APHIS PPQ, started on May 12 and ended on August 21. Adult survey data recorded economic levels of 8 grasshoppers per square yard and higher on 157,974 acres (2005: 64,751 acres, 2006: 97,399 acres, 2007: 798,358 acres, 2008: 1,129,820 acres) in 11 (2005: 9, 2006: 14; 2007: 13, 2008: 12) counties of eastern Oregon. In 2009, a total of 998 (2005: 859 and 2006: 1368; 2007: 1585, 2008: 2722) sites were visited of which 436 were nymphal and 507 adult survey sites, and 55 treatment sites.
The counties with the highest infestation levels this year were Harney with 75,987 acres, Malheur with 27,980 acres, Baker with 21,079 acres, Umatilla with 11,234 acres, Union with 4,832 acres, Morrow with 3,532 acres, Wallowa with 3,466 acres, and Grant with 2,894 acres.
The only area with significant infestations of more than 10,000 acres was located around the Malheur National Refuge (74,006 acres) in Harney 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. Early nymphal infestations reported on private rangeland around the Wildlife’s Buckpasture did not translate into economic adult infestations later in the summer. Nymphal surveys of the Lane Ranch in the northeastern part of the Klamath Marsh Refuge showed a heavily infested eggbed with Camnula hatching in masses. Counts of the approximately 1-acre large hotspot recorded about 50 first instar Camnula per square yard. However, later adult surveys did not show any economic infestations in this area.
Similar to the previous two years, adult surveys of the 2006-treated Fort Klamath area did not show any significant grasshopper activity this year.
The outbreak in Northeastern Oregon continued this year but was significantly suppressed by privately applied Dimilin hotspot treatments. In 2008 almost 740,000 acres in Baker and Wallowa counties were recorded with economic infestations of up to 74 grasshoppers per square yard. In early spring, in addition to technical assistance, Oregon Department of Agriculture and USDA APHIS PPQ offered to loan out spray ATVs and excess chemicals, Dimilin and 5% Sevin bait, to private ranchers and growers in the area to manage hot-spots identified in the previous outbreak years. Oregon State University Extension Service facilitated the rental agreements and helped with the logistics of the equipment and chemicals. In total 1,650 acres were treated with Dimilin and 5% Sevin bait in the Keating Valley, Haines, Baker Valley, Burnt River, and Medical Springs areas. Although smaller than in 2007 and 2008, the areas treated represented egg-laying areas identified in 2008. Treating these hot-spots early in spring likely helped to suppress adult populations in the 2009 summer season. This year the late season Baker County infestation was down to 21,079 acres.
In preparation for the continuous outbreak situation in Baker County, a grasshopper IPM workshop was held on February 13 in Baker City with specific information on the clearwinged grasshopper. The workshop was presented and organized by USDA-APHIS-PPQ, ODA and OSU Extension Service. In total, 10 participants attended the workshop, including pubic and private land-managers, ranchers and growers.
An area of 2,423 acres of BLM land was treated with Dimilin in the Keating and Medical Springs area in the largest aerial treatment program in over 15 years in Oregon. The treatment started on Monday, June 29 with pre-treatment counts and definition of water buffer zones. The plane was checked in and calibrated on Tuesday afternoon. First treatment started on Wednesday morning. Treatment ended on Thursday afternoon. 77% control success was recorded.
For a second year, economic Camnula populations at the Portland International Airport (PDX) were found along the runways. After early spring surveys, the Port of Portland (PoP) applied dimilin along the runways on a total of 312 acres. Pre and post-treatment counts showed a 100% control success.
Private Dimilin applications were conducted at the Drews Reservoir Ranch, Lake County, and at the Roaring Springs Ranch in Frenchglen, Harney County where about 7,143 acres and 2,100 acres, respectively, were treated with 50% RAATs. Pre- and post-treatment counts showed 93% mortality for the Drews Ranch application.
Adult grasshopper survey in other areas of eastern Oregon showed economic levels in Malheur, Baker, Umatilla, Union, Morrow, Wallowa, Grant, Jefferson, Wheeler, and Klamath 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.
A small population of Mormon crickets, Anabrus simplex, was recorded in a 200 acres area northeast of Enterprise, Wallowa County with economic levels of up to 25 per square yard. Control options were explained to the landowner but not implemented. Economic infestations of the Mormon crickets were reported on the Idaho site of the Jordan Valley but no calls for assistance were received from Oregon’s ranchers.
Table 1 (pdf, 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 2009 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 2009 serve as indicators of potential problem areas for 2010, and should be closely monitored in early spring of 2010.
Table 2 (pdf, KB)- Oregon Grasshopper Survey Statistics 2005-2009
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