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Growers switch herbicides for groundwater regulations

Oct 3, 2005 9:34 AM, By Linda Romander

Pesticide use reports for 2004 available late this year will tell the complete story, but in the meantime, a quick survey of ag chem dealers and pest control advisers (PCAs) in California counties dotted with newly designated groundwater protection zones indicates growers are largely switching products rather than hassle with the new regulations.

The requirement to either discontinue use of certain herbicides or adopt practices that prevent additional ground water contamination is part of the Ground Water Protection Program (GWPP). Begun in May 2004, the GWPP is designed to protect groundwater on about 2.4 million acres of California farmland identified by the California Department of Pesticide Regulation (DPR) as most vulnerable to pesticide contamination from leaching and runoff.

The state-designated 6800(a) list of herbicides includes atrazine, simazine, bromacil, diuron, prometon, bentazon and norflurazon, which have been found in well water. In order to continue using herbicides with these active ingredients, growers must apply for a permit and agree to follow a management practice designated by DPR to prevent groundwater contamination.

“There has been a big switch from using bromacil, diuron and simazine in citrus here in Tulare County, which has numerous GWPAs,” says Ed Murray, general manager of Orange Belt Supply Co., Lindsay, Calif. “The mitigating measures required for using a product on the list are not workable for our growers. This is why they are turning to other products,” he says. “A tremendous amount of citrus acreage has been switched over to Surflan (oryzalin), which gives equal, if not better, control and is not on the 6800(a) list. “We were initially concerned whether Surflan would hold up, but it has been doing a good job with residual control,” he adds. “Surflan has been used in the past, but it was more expensive. The price has come down now, and applications are being made at rates running from 2 quarts in the fall plus 2 quarts in the spring, to 3+1 or 3+2, depending on the PCA. These applications are lasting into the summer with a few escapes, which growers pick up by spot treating with contacts.

Compares well

“We find that Surflan compares well with diuron and simazine. With both treatments there are escapes, and you will have to come back a time or two with glyphosate,” the dealer says. “Some growers are going to multiple applications with contact herbicides in place of residuals, but this can be a problem in the winter when they can’t get in to spray.”

To Murray, the Ground Water Protection Program is important to protect the environment. “It’s not worth messing with the environment and the regulations,” he says. “Rules are rules. Let’s abide by them. If we don’t, in the long run products will be lost,” he advises.

Britz Fertilizers in Traver, Calif., serves stone fruit and grape growers in Fresno and Tulare counties. “The majority of our growers farm in Ground Water Protection,” reports branch manager John Montelongo. “I would say 80 percent of them are using other products rather than filing for permits to use the restricted products,” he estimates.

Britz’s growers are switching to Surflan, Devrinol (napropamide) and contact herbicides, the manager says. “Surflan has an advantage with its longer-lasting residual control, which is more cost-effective than using only contacts,” he says. “Devrinol works well if we can get water to it right after application, either with rain or irrigation. If we don’t get a rain and have to irrigate, that becomes costly to the grower.”

Devrinol has a handling advantage in that it comes as a dry flowable (DF) formulation, but this fall Surflan also will be available as a DF. “A couple of our growers have tried the new Surflan DF formulation and are pleased with it,” Montelongo says. “Container disposal is a big issue here; it is costly and inconvenient to rinse and dispose of plastic containers. And the new packaging is convenient — a case of 12-pound bags is equivalent to a 5-gallon container, and both the plastic bags and the cardboard case can be burned or disposed of at a landfill.”

Flowability, dispersion

Beyond the disposal issue, tests with Surflan DF have shown it to have good flowability and dispersion, resulting in easier pouring and measuring. The dry product blooms well in water and stays in solution. Spills are easily swept up, and don’t leave stains as liquid formulations tend to.

PCA Randy Radtke, Gar Tootelian, Reedley, Calif., reports that citrus, grapes and tree fruit growers have been most affected by the new groundwater protection rules. Radtke says that 80 percent of the acreage he writes recommendations for in Fresno and Tulare counties are in a groundwater protection area.

Citrus Mutual in Exeter, Calif., won approval for a mitigating practice for continued use of simazine and diuron by its members, according to Radtke. They are allowed to apply these 6800(a) herbicides up to the dripline of the trees, which is closer to 50 percent of the surface area instead of the 33 percent that is allowed under the groundwater protection regulations. The restricted products must be applied at a time when leaching or runoff is least likely. In the middles, growers use allowed herbicides such as Surflan, or a contact material.

On grapes and stone fruit, growers are switching to Surflan as an alternative to Solicam (norflurazon), the PCA says. “I use Surflan in grapes, almonds and walnuts. My growers switched to Surflan because they don’t want the hassle of applying for a permit. Growers are not happy to change their programs; it’s still a debate in many growers’ minds whether the GWPA is politics or science, but they understand it is important to abide by the regulations and look at alternatives as long as the economics are reasonable,” he says.

According to Radtke, the most popular program and the best combination of products he’s found for grapes and almonds in GWPAs is Surflan plus Chateau, a new herbicide that was just registered last year. “One gallon of Surflan plus 12 ounces of Chateau gives long-lasting residual control with far fewer escapes because the two products complement each other so well,” he says. “Chateau is strong on broadleaves — even better than simazine, and Surflan is strong on grasses.”

Crop applications

“In grapes, this combination is applied down the berm, and in almonds it is applied either solid or down the row with the centers mowed. We saw almost a full season of control this past year, even with the heavy spring rains,” Radtke reports. “This is a more expensive program, but there are far fewer follow-up contact spray applications needed. And it will be less costly for growers to use Chateau the second year as the labeled-rate will be lower.”

Replacing residuals with contacts has not been a popular program, the PCA says. “Growers who have switched to 100 percent contacts have found that there are too many escapes due to glyphosate resistance.”

Awareness of the groundwater protection program and compliance in his area is nearly 100 percent, according to Radtke. Nevertheless, the DPR continues its efforts to educate growers and PCAs about the new program.

“New programs take time to learn and will evolve as new information becomes available,” says DPR’s Mark Pepple, “so DPR outreach will likely be ongoing. Feedback at meetings has helped us develop the regulations in the first place and will provide valuable information for future activities,” he says.

Although no new GWPAs have been identified or added to the list this year, it is likely to happen in the future. “We have identified additional sensitive areas based on soil characteristics, and we are testing possible management measures for them,” Pepple says. “Once effective management measures are developed, or if pesticides are detected in these new areas, they will be identified as GWPAs.”

Pepple adds that staying ahead of the problem makes both environmental and economic sense. “How pesticides that can reach groundwater are managed today can affect groundwater quality in the years to come,” he says. “A strong continuing ‘investment’ in following the regulations will likely allow the continued use of effective, affordable pesticides in the future.”

The DPR groundwater Web site (www.cdpr.ca.gov/docs/gwp/index.htm) is a good place for growers to stay informed. It has been redesigned to focus on the new regulations, including lists and maps of GWPAs by county, identification of regulated pesticides, and lists and illustrations of the management practices that apply in leaching and runoff GWPAs.

Another good source of information is the Western Farm Press Web site (www.westernfarmpress.com) where there is a continuing education unit on the new groundwater regulations where PCAs and private, qualified and aerial applicators can earn one hour of DPR credit by taking an online course. The course is approved for one hour of laws and regulations by DPR. To date almost 500 licensees have taken the course sponsored online by Bayer CropScience.

Information on the program may also be obtained from local county ag commissioner staff, by contacting DPR staff directly at 916-324-4086, mpepple@cdpr.ca.gov or by consulting with knowledgeable PCAs in the area.

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