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Public Radio's Environmental News Magazine (follow us on Google News)

Recycling To Reduce Pesticide Use

Air Date: Week of

Methyl bromide might not be in strawberry fields forever if organic alternatives to the pesticide are successful. (Photo: Sara Stasi)

After years of searching for an alternative for the kill-everything soil fumigant methyl bromide, one company thinks it may have an answer: leftover mustard seeds from biofuel production. Amy Coombs reports.


GELLERMAN: Let us take you down along California’s Central Coast, where almost half of the nations strawberries are grown, there’s much to get hung about. A lot of the soil there is still treated with one of the world’s most controversial pesticides. But these treated strawberry fields may not be forever. The EPA has just set more stringent standards to protect workers and researchers are working on a non-toxic alternative. Reporter Amy Coombs has our story.

Pesticide of the future? (Photo: Stephanie Bourcier)

COOMBS: In his office in Salinas, California, Agricultural Commissioner Bob Roach scrolls through hundreds of pesticide use reports for methyl bromide.


ROACH: Methyl bromide is a general biocide, so it kills pretty much everything. That’s why it’s so effective. It’s effective against a lot of insect pests, mites, diseases like fungal diseases of the soil, nematodes, weeds.

COOMBS: It’s also extremely harmful if workers accidentally come into contact with it, and it’s one of the last major contributors to the hole in the ozone layer. This is why many countries have entirely quit using methyl bromide, and the U.S. committed to phase it out by 2005. But that hasn’t exactly happened. In most strawberry fields, methyl bromide gas is still pumped through the soil before planting.

ROACH: Probably 97 percent are grown using some sort of fumigation - either methyl bromide or one of the alternatives.

COOMBS: The federal government still offers better insurance premiums when methyl bromide is used, because the crops are considered less likely to fail. And since strawberries are one of the most expensive crops to plant, farmers say they can’t afford to experiment with alternatives. Despite years of research, many chemical replacements don’t seem to work as well anyway, and organic methods can take years to implement.

After mustard seed is pressed to make biodiesel or cooking oil, it leaves behind a brown meal that can be used as an alternative pesticide. (Photo: Stephanie Bourcier)

ROACH: It’s very difficult to grow strawberries without methyl bromide because of the diseases that are in the soil.

COOMBS: But now one company, called Farm Fuel Incorporated, may have a non-toxic option available - ground up mustard seed.


COOMBS: On a farm that overlooks the sea, the company’s biologist, Stephanie Bourcier, pours cups of seed meal onto rows of black earth.

BOURCIER: What we do now is apply the meal by hand into an already prepared bed.


COOMBS: As sea lions bark on the beach below the farm.


COOMBS: Bourcier smiles as she inspects rows of mature plants grown using seed meal.


BOURCIER: You can tell this is a healthy plant by these large healthy mature leaves, also there are young leafs sprouting. This plant also has many flowers and berries growing.

COOMBS: In one test Bourcier planted a field treated with seed meal next to one treated with methyl bromide. So far, the seed the meal seems to be working just as well as conventional methods - at least when it’s applied in the right concentrations.

BOURCIER: We are trying to figure out how much meal needs to be applied for strawberries - how much is too much? How much is too little? What we want to find is the right balance, so we will apply the meal by different weights.

COOMBS: Farm Fuel still has to test the seed meal on large plots - with tractors and industrial techniques - before its marketable. But Sonoma State University biologist Mike Cohen predicts this will go smoothly. Cohen has studied the properties of ground seed, and says they contain glucosinulates - the same types of compounds found in horseradish that make your mouth burn.

Strawberry fields in Watsonville, California. (Photo: Sara Stasi)

COHEN: When the seed meal is applied to the soil it comes in contact with moisture. That activates the glucosinulates to break down and release fumigants that act on the pathogens and inhibit them or kill them.

COOMBS: Cohen also discovered seed meal has another benefit. It cultivates good bacteria in the soil, which helps the plants produce root hormones, strengthening their resistance.

COHEN: The seed meal also works by stimulating the growth of bacteria that help plants defend themselves against pathogens.

COOMBS: This is a very different approach to pest management, says Cohen. Over time, the seed meal helps the soil become healthier, while Methyl bromide may pave the way for more pathogenic invasions.

COHEN: So the strategy with methyl bromide is simply to wipe out everything in the soil - the entire community. Basically what you have established then in the soil is a vacuum, in which if a pathogen lands it can quickly invade since it doesn’t find any competitors, and reproduce and spread in the soil, thereby necessitating another application of the fumigant not very far down the line.

COOMBS: It’s a difficult cycle to break. This is why Agricultural Commissioner Bob Roach says despite seed meal alternatives, farmers aren’t going to abandon something they know works. Even if the seed meal proves itself in the field, it will likely have to be combined with other organic farming methods, and the industry might not be open to this much change.

ROACH: The production system using fumigation to produce strawberries has been around for a lot of years, and it’s a very successful pest management system. You fumigate, you basically clean up all pests, all weeds, and you don’t have any more problems with those when you use methyl bromide.

COOMBS: Yet eventually farmers will have to make a break with methyl bromide. Even though the industry has delayed, the chemical will be phased out. Bourcier hopes that even if seed meal doesn’t kill everything in the soil, it’s quick acting purification will help more farmers switch to organic methods. If tests go well, Farm Fuel will begin testing seed meal on large-scale farms next year. In the mean time, Bourcier hopes people will make an effort to buy organic strawberries.

For Living on Earth, I’m Amy Coombs



Check out Living on Earth's previous coverage of methyl bromide


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