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The tree fruit industry is urging the U.S. Environmental Protection Agency not to require buffer zones around orchards when they are fumigated for replant disease.

The EPA, which is reviewing several fumigants as part of the reregistration process, has proposed buffer zones of up to 4,600 feet (eight-tenths of a mile) to mitigate the effects of fumigation on the environment surrounding farms. The Northwest Horticultural Council says buffer zones of that magnitude would make soil fumigation in orchards impossible. It has told the EPA that it believes that good agricultural practices, including good field preparation and proper sealing techniques, are a more viable way to reduce the risk of emissions and exposure.

Replant disease

The Pacific Northwest has about 300,000 acres of apples, pears, and cherries, of which about 8,000 acres (2.6 percent) are replanted annually, according to the Hort Council. About 80 percent of the replaced acres are fumigated, it is estimated. A combination of Telone and chloropicrin is the most common treatment.

Fumigation is critical because trees planted into old orchard sites are likely to suffer from replant disease, the council told the EPA. Replant disease is thought to be caused by fungi, bacteria, viruses, or other organisms that survive in decaying roots in the soil and affect the weak roots of the young trees.

New trees do not establish well in unfumigated ground, and their poor growth has a negative impact on the long-term productivity of the orchard.

The EPA is assessing risks and will develop risk management decisions for five soil fumigants: chloropicrin, dazomet, metam sodium, methyl bromide, and a new fumigant iodomethane, which was registered last year for one year only.

It is also evaluating the risks of Telone (1,3-dichloropropene), though the risk-management decision for that product was completed ten years ago. The review is part of the EPA’s program to ensure that all pesticides meet current health and safety standards, according to information on the EPA’s Web site.

Methyl bromide (alone or in combination with chloropicrin) and Telone/chloropicrin combinations have been the fumigants most commonly used in the tree fruit industry, but use of methyl bromide has been phased out, the Hort Council reports.

The fumigant metam sodium is not ideal for orchards because it needs to be applied with water, and orchard fumigation is often done while the irrigation system is off for the season. Results of fumigation with metam sodium are often inconsistent, the Hort Council told the EPA in written comments. If too much water is applied, the treatment is ineffective. If too little is applied, the fumigant doesn’t reach the target treatment zone.

No complaints

Dr. Mike Willett, vice president for scientific affairs at the Hort Council, said there’s a relatively small amount of orchard land being fumigated in comparison to annual crops, and that there has never been a complaint about off-site movement of fumigants used to treat orchard replant disease in Washington.

Agricultural groups have told the EPA they favor the use of good agricultural practices rather than a label change that requires blanket buffer zones.

Good agricultural practices cover: fumigant choice, application rate, wind speed, soil temperature, soil preparation, soil moisture, field management, prevention of spillage, application depth, application method, worker protection, soil sealing, and reentry restrictions.

In a letter to the EPA, the Minor Crop Farmer Alliance said that the agency should have a thorough understanding of what the industry is currently doing and have reliable evidence to demonstrate it is insufficient before embarking on a road to impose additional restrictions on the use of the fumigants.

Andrea Carone, chemical review manager in the EPA’s Special Review and Reregistration Division, said the EPA is working towards issuing a decision in May.