Dimethoate Use on Succulent Peas and Beans in the Pacific Northwest

Date: Tuesday, Aug. 5, 2003
To: Pat Dobak, EPA
From: Doug Walsh
Subject: Dimethoate Use on Succulent Peas and Beans

Pat Dobak,

Please forward this message to the appropriate people for me in regards to the sugar snap peas we produce in the Pacific Northwest.

There is no cost effective replacement for dimethoate applied by air. Our sugar snap producers main target pest is Western flower thrips. Injury takes place at and immediately after bloom. Dimethoate is registered in Washington State under a 24C and it is applied by air at around 25% bloom and then a second application is made about 7 to 10 days later. Harvest can be as early as 3 weeks after the second application.

A secondary pest our growers have too is the Lygus bug. Dimethoate in this use pattern controls Lygus bug. Alternative products like imidacloprid or spinosad are ineffective against Lygus. Imidacloprid is ineffective against Western flower thrips and spinosad is cost prohibitive for thrips control.

Please contact me if I can provide provide any additional information.

Doug Walsh, Ph.D.
IPM Coordinator
Washington State University
509-786-9287