Response to Effect of Proposed Mancozeb Mitigation Measures in California on Processing Tomatoes

Date: August 2, 2005

To: Rich Michell
Plant Pathologist-Nematologist
USEPA, OPP, BEAD (7503C)
Phone: (703) 308-8119
Fax: (703) 308-8091

CC: Rick Melnicoe
WIPMC director

From: Charles J. Rivara
Director
California Tomato Research Institute, Inc.

Subject: Response to Effect of Proposed Mitigation Measures in California on Processing Tomatoes

Dear Mr. Michell,

I was contacted this afternoon by Rick Melnicoe of the Western Integrated Pest Management Center regarding Mancozeb re-entry interval (REI) lengthening. I work for the processing tomato industry in California and my remarks are limited to the processing crop only, not the fresh market industry.

Mancozeb HAD been primarily used as a preharvest fungicide for ripe fruit molds. With the change in labeling a few years ago it is now mostly used as a synergist for copper in bacterial disease treatments. The use of mancozeb has become critical since we have recently lost genetic resistance to the the primary bacterial disease, Pseudomonas syringae, pv tomato. AKA bacterial speck. This past season many fields were severely damaged due to the copper resistant strains of this new race1 speck.

I reference the old preharvest use as a longer REI would not be an issue for that use. The current use is early and mid-season in the crop cycle making irrigator re-entry very important. To enable ground sprayer access, irrigations are delayed thus necessitating an immediate post treatment irrigation. We have been looking for better efficacy alternatives to copper/mancozeb, but have not found any to date. If we could keep irrigators on the old REI that would be workable for this critical use.

I will be out of the office until Monday Aug 8, and am happy to work with you further on this subject.

Chuck

Charles J. Rivara
Director
California Tomato Research Institute, Inc.
Phone: (209) 838-1594
Fax: (209) 838-1595