The New Food Quality Protection Act Increases TOMCAST Fungicide Options

by Jim Jasinski, OSU Extension IPM and R. M. Riedel, Plant Pathology

Prior to July 1996, the Delaney Clause of the Federal Food Drug and Cosmetic Act prohibited use of pesticides suspected as potential carcinogens on processed foods if detectable residues could be found in those products. This clause disallowed use of EBDC fungicides and other pesticides on processed foods because minute residues could be detected in the finished product. On July 23, 1996, Congress re-examined and reformed the stringent Delaney Clause. They chose to set a new standard of tolerance based on "reasonable certainty of no harm" broadly interpreted as meaning that trace amounts of pesticides should pose no reasonable risk of harm, including aggregate exposures from food, water, and other non-occupational exposures. This new standard is the Food Quality Protection Act (FQPA) and allows for a wider spectrum of approved pesticides to be used on processed foods.

Impact on TOMCAST

The former Delaney Clause posed many constraints on the processing tomato industry. Since TOMCAST, a predictive disease model, was also developed under these same constraints, exposure to fungicide programs outside of Chlorothalonil (Bravo, Terranil, Echo) has been limited. Consequently, most research concerning appropriate TOMCAST Disease Severity Values (DSV) spray thresholds by location or fruit quality are based on observations of Chlorothalonil. With recent passage of FQPA, the number fungicides legally labeled on processing tomatoes in 1997 has increased. To help growers transition from Chlorothalonil to other products and spray regimes, some DSV guidelines have been developed. It should be understood that Ohio State University is only offering suggestions to modify current DSV spray intervals. It is incumbent upon growers to decide if these suggestions are worthwhile to their operation and acceptable to processors.

In general, spray thresholds should be shortened 3 DSV, from 18 to 15, for products such as Dithane, Mancozeb, and Ziram as compared to Chlorothalonil. For growers who intend to use Quadris, a fungicide labeled in 1998, DSV spray intervals should remain the same as a Chlorothalonil program. Quadris is a new class of chemical. It has broad spectrum activity on tomato. It has given very good control of Early Blight, Septoria Leaf Blight, and Pythium ground rot in our tests. Quadris also gives good control of Anthracnose and Late Blight on tomato, and controls Powdery Mildew on other crops; the latter has not been tested in Ohio. Quadris also has low toxicity to mammals. On a calendar schedule Quadris will likely be applied on a 10-14 day schedule. At no time apply more than four consecutive Quadris treatments.

Since Quadris is a new material, growers should familiarize themselves with the fungicide by applying it to a small portion of their acreage to compare its efficacy and effects on quality with their traditional disease control program.

The DSV Hotline call can be made 24 hours a day, and usually lasts between 1-2 minutes. A phone number is given at the end of the recording to reach Jim Jasinski at: 937-454-5002 if there are additional questions.

Some Suggested Fungicide Programs

1. Dithane (Mancozeb) and Copper for the first two sprays or until fruit is 1/2", then finish the season with Chlorothalonil (Bravo) alone or in copper to control bacterial diseases;
   
2. Chlorothalonil season long;
   
3. .Dithane in the first two sprays (or until fruit is 1/2") followed by four sprays of Quadris and finish the season with Chlorothalonil. Quadris sprays applied in July will control Septoria Blight without the addition of Benomyl to spray program.
   

Ziram can be substituted for Dithane as an early season fungicide. The above fungicide programs are only suggestions and by no means inclusive of all possible spray programs. Select a program that best fits the needs of your farming operation.

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