Almond growers must navigate a maze of soil fumigant restrictions

A web of soil fumigant regulations related to air quality and worker/bystander exposure is casting a cloud of uncertainty over the ability of almond growers to use soil fumigants on new or replanted orchards.

Adding to the uncertainty, a federal appeals court in August overturned a ruling by a lower court that the California Department of Pesticide Regulation (DPR) order farmers to reduce pesticide volatile organic compound (VOC) emissions by 20 percent next year.

New state rules that went into effect this year to meet the lower court's ruling are aimed at reducing pesticide VOC emissions in the San Joaquin Valley. These rules severely restrict the application window and methods for most almond soil fumigants.

Now that this ruling has been struck down, DPR has the option of suspending the VOC regulation; however, a spokesperson for DPR points out that the department still has the 2007 Ozone State Implementation Plan commitment to reduce pesticide air emissions starting this year in the San Joaquin Valley. In addition, new EPA mitigation measures are expected to show up on 2010 labels that will place further burdens on the application of soil fumigants statewide.

Add to that a tightening noose on the availability and ability to use methyl bromide under terms of the Montreal Protocol, and growers are left with a complicated decision about how to treat for replant soilborne pests and diseases.

Given the uncertainty about the cost, availability and usability of soil fumigants in California, it is important that almond growers understand the changing regulatory requirements as well as which pest issues in the soil they are trying to address with a fumigation, to select the option with the best chance of fitting within new restrictions for applying soil fumigants.

Here is a look at the new regulations as they now stand for almond growers and others who rely on soil fumigants in California.

The DPR in January rolled out regulations on soil fumigants in an effort to curb pesticide emissions of smog-forming VOCs during the peak ozone period from May 1 to Oct. 31. Fumigant applications in areas of the state with the dirtiest air, including the San Joaquin Valley, will be limited to lower emissions methods. That means, for example, that strip applications of methyl bromide are no longer allowed in the SJV during the ozone season.

The other component of the regulation was to set VOC emissions caps from all pesticides, of which soil fumigants and non-fumigant EC formulations are the two major contributors. Because regulators now say that non-fumigant pesticide use is accounting for a greater share of total pesticide VOC emissions in the San Joaquin Valley than originally estimated, there is a very real chance that no soil fumigations may be allowed during the ozone season in 2009.

If that is the case, SJV growers may have to apply fumigations after Nov. 1, when cooler and wetter soils may affect the efficacy of those fumigants, or forgo applications altogether.

Layered on top of the new DPR regulations, the U.S. EPA in July announced a long-awaited set of federal rules intended to reduce worker and bystander exposure risks from soil fumigant applications.

EPA's new risk mitigation measures will go into place in 2010, when new labels will be issued for the fumigants methyl bromide, chloropicrin, dazomet, metam sodium and metam potassium. The soil fumigant 1,3-D (Telone) will be evaluated again when all fumigants come under review in 2013.

The final EPA proposal now classifies all fumigants as restricted use pesticides, meaning only certified applicators can apply and oversee fumigant operations. Those applicators will be required to complete written, site-specific fumigant management plans before fumigations begin. And new requirements will be implemented related to respiration equipment, tarp removal, field re-entry and application rates, methods and practices. The maximum rate for methyl bromide has been decreased to 200 pounds ai/A for tree replant.

The rules also require buffer zones around treated fields and require all fields to be posted with information about the location and timing of fumigations and associated buffer zones. Growers will either have to have continuous monitoring of fumigant levels around their fields, or they will have to notify their neighbors living near the field several days prior to the application.

While the decision is final, EPA is accepting written public comment related to implementation of the new regulations until Sept. 15. An extension of this deadline to Oct. 15 is expected as of this writing. For guidance on how to comment, log on to:

And finally, under the Montreal Protocol phase-out, stockpiles of methyl bromide have been depleted and only a small amount of methyl bromide is available under negotiated Critical Use Exemptions (CUE). Almond growers can only use CUE-allocated methyl bromide if the alternative Telone is limited either by township caps or heavy soil conditions that would render Telone ineffective. With the limited availability, the cost of methyl bromide has risen substantially.

Given these three major regulatory challenges to soil fumigation, almond growers and others who rely on soil fumigants for the control of soilborne pests must carefully assess the situation in the soil and make contingencies to find a way to comply with the costs and requirements of these new rules. Growers who are thinking of replanting, especially if they are in the San Joaquin Valley, might consider doing it this fall because of the regulatory uncertainty for 2009.

A future column will offer some of the findings of ABC-funded research on fumigation to help almond growers make decisions in light of increasing regulations. Additionally, potential tools for soil pest management will be one of the “Hot Topics” discussed at this year's Almond Industry Conference, Dec. 10-11 in Modesto. To register, visit

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