Dimethoate Reregistration Review Information Request -- Additional Pacific Northwest Response for Idaho and Oregon
From: Jane M. Thomas
Sent: Monday, February 08, 2010 2:14 PM
To: Rogers, Ted
Subject: Adendum to Response for Dimethoate Use in
the PNW
Ted -- Below is additional information on the use of dimethoate in the PNW. This information from Jim Barbour with the University of Idaho covers the use of dimethoate on alfalfa and alfalfa seed grown in Idaho and Oregon. -- Jane
Jane M. Thomas
Pacific
Northwest Comment Coordinator
Pest Management Resource Service
Washington State University Tri-Cities
2710 University Drive
Richland, WA 99354
phone: 509-372-7493
fax: 509-372-7491
Hours: 7:30 to 5:00 Monday and Tuesday, 8:00 to 12:00 Wednesdays, off
Thursday and Friday.
From: James Barbour
Sent: Wednesday, February 03, 2010 10:48 AM
To: Jane M. Thomas
Subject: RE: Response: Dimethoate Use in the PNW
Jane Thomas,
Thanks for accepting the information from Idaho and eastern Oregon regarding the review of dimethoate and its use in alfalfa seed and alfalfa hay. As indicated below the information for alfalfa is seed based on a high percentage of the acreage in the Treasure Valley and should be quite accurate. The information on alfalfa forage is based on use patterns in similar production areas and from the use patterns reported to EPA in 2003.
Alfalfa seed:
I have been able to contact growers and/ or seed company representatives representing 70% to 80% of the of the 10,000 to 12,000 acres of alfalfa seed produced in Idaho and eastern Oregon. Dimethoate is an extremely important part of the pest management regime used by Idaho and eastern Oregon seed growers. It is used pre bloom (before pollinators are present) and post bloom (after pollination is finished) to control lygus bugs and aphids. More than 90% of the acres is treated once with dimethoate pre-bloom, generally as a tank mix partner with a pyrethroid or other insecticide. Additionally, 50% to 70% of the acres receives a second application of dimethoate post-bloom to protect developing seed from lygus bug feeding damage. Dimethoate is effective, inexpensive and fits well in the rotation with other available pesticide chemistries.
Alfalfa:
I have little direct information on use of dimethoate in alfalfa forage. Reports from a few growers indicate a use pattern not unlike that in Washington, or described in the response to EPA filed in 2003 and available at http://www.wsprs.wsu.edu/USDAEPAInfo.html. Dimethoate is important to hay growers for control aphids and alfalfa weevil. It is likely that 60% to 80% of the acres treated once, and a smaller percentage, 15% to 20%, treated twice.
Best regards,
Jim Barbour
IPM Specialist
University of Idaho
SW Idaho Research and Extension Center
29603 U of I Lane
Parma, ID 83660-6590
Phone: 208 722-6701
Fax: 208 722-6708
