California Strawberry Industry: On the Learning Curve

“For many California strawberry producers, there is a tremendous feeling of uncertainty right now,” says Dave Riggs, president of the California Strawberry Commission. Growers are concerned about how soon alternatives to methyl bromide will become available. They want the time to figure out how to best use any alternatives before they become dependent on them.

“We cannot think that we still have a 6-year time horizon to find an alternative to methyl bromide. You can’t deliver an alternative on the deadline [in 2005] without allowing time to resolve regulatory issues and for the farmer to learn how to use it.”

Riggs explained that some growers feel like they are caught in a Catch-22. Many alternatives are not yet available for them to experiment with, but they need time to figure out how to use any replacement effectively and efficiently before they can balance their survival as a business on it. Many proposed alternatives have not yet cleared regulatory hurdles, he pointed out. Methyl iodide has only recently started down the registration and manufacturing path. Telone and chloropicrin are registered but still face unresolved regulatory restrictions.

“One compound that is always mentioned by EPA [U.S. Environmental Protection Agency] is Basamid, but it is not registered yet and it is a very tricky compound to apply,” he said. Research has shown that Basamid may be efficacious, but it can be highly phytotoxic if not properly applied, and its phytotoxicity varies with climate, soil type, method of application, and other factors. “Only when individual farmers learn to use the compound safely and effectively on a large scale, can it really be considered as a workable alternative,” Riggs said.

The California Strawberry Commission and USDA’s Agricultural Research Service (ARS) have been cooperating in testing alternatives on field plots with various growers since 1996. During the 1998–99 growing season, ARS helped conduct trials in six growers’ fields. In all of the trials, the tested chemicals were applied by conventional shank methods and on five of them through existing drip irrigation.

In terms of combating fungal and other diseases, tests with a combination of Telone and chloropicrin and with chloropicrin by itself brought yields to within 5–15 percent of those with methyl bromide, according to Thomas Trout, one of the ARS scientists overseeing the trials. “That still leaves the problem of weeds, but it is a good start,” Trout pointed out.

Adapting Takes Time

Trout agrees farmers will need time to learn how to adapt alternatives. Using Telone and chloropicrin combined or alone instead of methyl bromide will, at the very least, require growers to adapt their schedules because these chemicals require longer delays before treated fields can be planted—as much as 3 to 4 weeks compared to a few days.

“Growers may lose a week or two of harvest at one end or the other of the season with these alternatives, although this will vary widely among growers depending on their location and cultural practices. I think we are at the stage now where we know there will be some problems, which we will continue to try to resolve so alternatives like Telone and chloropicrin remain available,” Trout added.

The cooperative testing program receives $100,000 a year from ARS, as well as funds from the commission and the state of California. “This research has given the industry as a whole a better understanding of how our next best alternatives [to methyl bromide] may fit into current farming practices,” Riggs said.

While strawberry producers are exploring alternatives, a wholesale changeover for most is not yet feasible, according to Riggs. “Farmers must meet today’s payroll in today’s competitive environment. They use the best tools available to be productive, efficient, and competitive with other California farmers and farmers in other states, as well as with farmers in Mexico who will be able to continue to use methyl bromide,” he explained.

Minimizing Potential Losses

What has Riggs and many producers concerned is the potential economic losses that may come in the years following the first year without methyl bromide unless an effective alternative is already a familiar tool for growers.

“The 1993 National Agricultural Pesticide Impact Assessment Program report noted a potential for a 10-percent loss in strawberry production the first year of production without methyl bromide. The Strawberry Commission data also indicate the potential for cumulative losses of 20 percent the second year and 30 to 40 percent in subsequent years due to the buildup of disease organisms in the soil that are not completely controlled by alternatives,” Riggs said. “The NAPIAP report also does not take into consideration catastrophic losses from flare-ups of Verticillium or Phytophthora diseases, which can completely decimate an entire field. This not only increases the risk of farming, it also jeopardizes the ability of the farmer to secure financing.”

So far, the cooperative field trials, which in some cases have been as long as 3 years back-to-back in the same plot, have not shown signs of flare-ups of these diseases even when conducted on plots not previously treated with methyl bromide—so there is hope for control.

Riggs does not expect that any one alternative to methyl bromide will enable farmers to make up losses. Rather, he believes that farmers will have to find many 1- to 2-percent improvements that will balance a major loss from not having methyl bromide.

“Farmers will have to make up the losses somewhere in production in order to make a profit, because they can’t expect price increases to make up the difference,” Riggs said. California strawberries are not only in competition with strawberries from countries where methyl bromide will still be allowed, they are also in competition with other choices like bananas and pineapples.”

The problem is really that none of the chemicals being discussed now treat the soil as completely as methyl bromide, according to Frank Westerlund, director of research for the California Strawberry Commission. One of the biggest differences for most of the proposed alternatives is how far these chemicals will move through the soil by themselves. When methyl bromide is applied 12 inches deep in soil, it will penetrate another 1 to 2 feet on its own. Telone moves only 6–12 inches deeper when similarly applied, Westerlund explained, so the soil is not as completely treated.

There is also the possibility of a biological control alternative to be considered, according to Westerlund. “People talk about methyl bromide sterilizing the soil. That isn’t the case in strawberry fields where methyl bromide is used either as a stand-alone product or when it’s mixed with chloropicrin,” he said.

Microorganism populations are simply suppressed for a time and then return slowly rather than the soil being recolonized from the outside. This leads to the possibility that beneficial microorganisms could be injected into the soil to fill the ecological niche, preventing the buildup of damaging fungi and other microbes.

“But could the beneficials out-compete the pathogens in soil that has a full existing population?” Westerlund wonders. “That’s an area we need to research under commercial conditions. How biologicals will fit into commercial operations is far from resolved, even in the research environment.”

Westerlund added one more point the California Strawberry Commission considers a major concern as the coming methyl bromide reductions increase the demand for alternatives. “We are very skeptical of some aggressively promoted alternatives whose sponsors have not been involved in established research protocols or objective scientific evaluation, or specifically in our controlled studies,” he said. “When the next 25-percent reduction comes in 2001, it will substantially increase costs and push more farmers to experiment with novel alternatives. I expect we will see a lot of hype and I don’t want to see farmers hurt by methods that are not well substantiated.”

Last Updated: July 1, 1999