Dimethoate Use in California

Date: Mon, 02 Jun 2003 15:19:05 -0700
To: Pat Dobak, EPA
From: Rick Melnicoe
Subject: Dimethoate

Dear Pat,

Thank you for the opportunity to answer your questions regarding dimethoate use in California.

Specifically, you requested information on broccoli, cauliflower and leaf lettuce.

I previously sent you a file containing information from the 2001 Pesticide Use Reporting system on all uses of dimethoate on California crops. In that file you will see that the median application number per crop is one, with a few growers applying up to 3 or 4 applications per crop. I spoke with both Ed Kurtz, Manager of the California Lettuce Board, and Belinda Platts, Agricultural Supervisor for Dole Fresh Vegetables, Inc. They provided the following information.

Broccoli and cauliflower receive only one application of dimethoate per crop. Virtually never is a second application made. Aerial applications are never made in the Monterey area.

Leaf lettuce receives one application of dimethoate per crop 50-70% of the time. A second application will be made 20-50% of the time. Additional applications are not made. Aerial applications are not made to leaf lettuce, as good coverage is needed. Therefore all applications are made using ground equipment.

It is important to have a second application available to growers of leaf lettuce as alternative materials are expensive and slower acting. Additionally, the 14 day PHI cannot be increased. A REI of 24-48 hours is acceptable.

Ms. Platts agrees with my comments that I discussed with you over the telephone about the potential for dimethoate residues to contaminate drinking water in Monterey County. Specifically, there is very little drift or off-site movement to waterways. These waterways are drains which move into sloughs or estuaries and out to sea. No drinking water sources are among these waterways. No reservoirs would be contaminated, either.

If you have any further questions, please contact me.

Sincerely,

Rick Melnicoe Director, Western Region Pest Management Center
Director, Office of Pesticide Information and Coordination (UC Statewide Pesticide Coordinator)
One Shields Avenue
University of California
Davis, CA 95616-8588
Telephone: (530) 754-8378
FAX: (530) 754-8379
E-Mail: rsmelnicoe@ucdavis.edu
http://www.wrpmc.ucdavis.edu