Loss of Methyl Bromide: Impact on the Strawberry Nursery Industry

Decades ago, growers dreamed of an ideal fumigant that would kill disease organisms without affecting the commodity, leave no harmful residue, not corrode equipment, be effective in low concentrations and short treatment periods, and be moderate in cost and readily available.

Methyl bromide—which is now used throughout the world on more than 100 commodities—comes very close to being that gaseous fumigant. But under the U.S. Clean Air Act, methyl bromide will no longer be available for growers in the United States on January 1, 2001.

One segment of the U.S. economy that will be hardest hit by this fast-approaching ban is the strawberry nursery industry.

"All the strawberry nurseries in California use methyl bromide to fumigate for soilborne pathogens," says Curt Gaines. He is general manager of the Lassen Canyon Nursery in Redding, California, the world's largest commercial strawberry nursery. "Even organic growers use plants from fumigated soils and still maintain their organic status. California growers are responsible for 85 percent of the U.S. strawberry production, and they help supply the international market as well. Most commercial strawberry varieties used internationally come from commercial California nurseries."

According to Gaines, the main purpose of a strawberry nursery is not to just mass produce plants, but to produce those plants with a minimum number of pathogens present. "We must certify to growers, in writing, that our plants are basically pathogen free. Now we can do that because we have the protection of methyl bromide. This chemical, combined with other soil fumigants like chloropicrin, eliminates the chance of nematodes or pathogens like Verticillium or Phytophthora attacking our plants. We nurserymen are liable to growers for clean plants. Losing methyl bromide poses a risk factor that most of us can't afford."

Nurseries are responsible for their strawberry plants being true to variety, Gaines says. If plants come up with a disease problem that the nursery could have generated, then the nursery must accept liability to the growers.

One nursery plant can actually produce 100 million other plants before being eliminated from the California strawberry certification program.

"Lassen Canyon Nursery has been involved with University of California scientists on a fumigation project that has been testing possible alternatives to methyl bromide for seven years. So far, I haven't seen a viable alternative that works as well or as consistently as methyl bromide," he says. "Telone with chloropicrin works fairly well, but the use of Telone is already restricted in California. If we didn't have methyl bromide, most existing nurseries in California would probably be forced out of business. We just couldn't face the potential liability problem."

Gaines is worried about the cumulative effect. Growers may do fairly well with some alternatives for the first year after fumigation. But what about the second year, the third, the fourth, and so on?

Not only do California nurseries supply strawberry plants to growers throughout the United States, but to nurseries in Canada that turn around and supply Florida growers. "We also supply the East Coast with plug and plant production. We supply plants to the Spanish nursery industry, most of Western European countries such as France, Italy, Greece, Morocco, Tunisia, and Portugal, as well as Mexico, Argentina, and other South American countries. In fact, we ship our plants to practically every country in the world except where there are phytosanitary restrictions. These plants come from the same strawberry varieties introduced by scientists at the University of California. The Spanish strawberry industry has been basically designed after the California industry, using California-developed technology," Gaines says.

The loss of methyl bromide will simply shift the strawberry nursery industry to another country that can still use it, he says. "In the first year we used methyl bromide, we increased production by 30 percent. Strawberry plants are in the ground for less than a year, which means that growers must get new, disease-free plants every year. An acre of nursery strawberry plants costs about $20,000 and plants out at about 40 acres of fruit, which can cost the grower about $500,000. And that doesn't even include harvesting costs."

This is just too much of a risk for most growers or nurserymen to face without methyl bromide or a proven alternative.

Tim Nourse, president of Nourse Farms, Inc., in South Deerfield, Massachusetts, agrees that the risk is great. "Our certified plants are the basis for the strawberry growers' livelihood. Their income depends on our plants' being pathogen free."

Nourse Farms is the largest nursery on the East Coast, supplying the East Coast, West Coast, and Midwest, as well as international markets, with certified strawberry and bushberry (including blackberry and raspberry) stock.

"We used to get our certified virus-free stock from the U.S. Department of Agriculture. But since 1980, we've been propagating our own in a lab on our premises," Nourse says.

Nourse Farms now begins the process with tissue-cultured stock (or clones) that has been virus tested and heat treated to eliminate disease problems. "Once we have a clean clone, we take the meristem tissue from that plant to begin the tissue culture propagation process. Once plant tissue is in culture, we make transfers or subcultures every three to five weeks to mass produce the amount of stock required for the certification process. We then transfer plants to the greenhouse to establish roots, getting them ready for field planting." Nourse says.

Methyl bromide is used to maintain these pathogen-free plants, he says. "We've tried other fumigants, but methyl bromide is the most successful and economically viable treatment. I've been in the strawberry nursery business for 30 years and don't see how we can go back to the days of the 1940s and 1950s when we had little understanding of how to control pests like nematodes and soilborne diseases. With today's advanced technology, we have a much better understanding of these pests and know that we must eliminate them. Although some potential alternatives to methyl bromide control nematodes, it's the soil fungal diseases that worry us more."

This is because of the cost. According to Nourse, "Using any of the alternatives available now would substantially increase our costs to meet the zero threshold for nematodes and soilborne diseases that we must meet for growers to feel safe with our plants. It now costs us about $80,000 each year to fumigate our nursery with methyl bromide. To do a comparable job with an alternative would cost substantially more."

Many of the growers in the eastern United States don't fumigate their strawberry fields. "They use crop rotation to control nematodes and soil fungal diseases. But, eastern and Midwestern growers are fortunate in that they farm other crops besides strawberries and can rotate those crops because of a short growing season and cold weather which affects the growth of soilborne pests and diseases. Growers in California, Florida, the Carolinas, Georgia, and eastern Virginia are more dependent on methyl bromide because a longer growing season creates more disease and pest pressure."

Also, he says, these growers don't have the luxury of a lot of crop rotation. They may rotate a crop of lettuce with their strawberries, but they don't have the option of crops like sweet corn or squash—like eastern and Midwestern growers have—because they may have 100 acres to plant. And that much acreage of the rotation crop may not be economically feasible. Therefore, the grower in a warmer climate ends up planting strawberries on the same land year after year.

"Although we fumigate with methyl bromide, in our own nursery in New England, we still follow a three- to five-year crop rotation plan," says Nourse.

Nourse says that many growers will be forced out of business if more economical alternatives aren't found by 2001, but those who remain will need plants that are certified pathogen free. "We'll be hard pressed to produce those plants economically without methyl bromide."

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Last Updated: Ocbober 6, 1998