MeBr Phaseout and Florida Floriculture

Florida is the second largest floriculture producer in the country, with over $650 million in sales in 1998. More than 1,500 growers commit 14,500 acres to floriculture, including cut flowers, potted flowering plants, and bedding/garden plants.

While floriculture is a vital part of Florida's agricultural economy, it pales in comparison to other crops in the amount of methyl bromide used. The U.S. utilizes about 38 percent of all methyl bromide applied worldwide each year. About 79 percent of the methyl bromide produced in the U.S. is used for soil fumigation before planting crops, about 9 percent is used to fumigate harvested commodities during storage and export, and about 5 percent is used for structural fumigations, such as for food processing plants, warehouses, museums, antiques, and transport vehicles. The remaining 7 percent is used in the production of other chemicals.

Florida accounts for about 38 percent of preplant methyl bromide use in the U.S. Fresh-market tomatoes and peppers grown in Florida account for about 33 percent of the Nation's preplant methyl bromide use and about 88 percent of the State's preplant methyl bromide use. Strawberries account for an additional 8 percent of preplant use there. Together, strawberries, tomatoes, and peppers constitute 96 percent of preplant methyl bromide used in Florida, providing a strong impetus to find methyl bromide alternatives for these crops.

The remaining crops, including floriculture crops, use about 4 percent of preplant methyl bromide. Unfortunately, because this sector of agriculture uses such a small amount of methyl bromide, the stimulus to fund research has been very low. However, some potential alternatives for caladiums and chrysanthemums have been identified.

Caladiums

More than 95 percent of the world's production of caladium tubers comes from a small geographical region close to Lake Placid, Florida. Most of the production is on muck or high- organic-matter soils. Soilborne pest control is a major problem for producers. These pests include weeds, root-knot nematodes, and soilborne diseases, such as Fusarium.

James Gilreath, Robert McSorley, and Robert McGovern, at the University of Florida, Gulf Coast Research and Education Center, in Bradenton, studied soil fumigant and herbicide combinations for soilborne pest control in caladium in 1998. Treatments consisted of methyl bromide + chloropicrin (90 percent/10 percent), 1,3-dichloropropene + chloropicrin (83 percent/17 percent), and metham + chloropicrin (75 gal/acre + 200 lb/acre. A nontreated control was included in the study. Plots treated with 1,3-dichloropropene or metham were given soil-surface sprays of metalochlor during planting and oryzalin about 7 weeks later. Plots treated with methyl bromide received only oryzalin; nontreated controls received no herbicide and were hand weeded.

Early (25 days after application in midsummer) weed control was good with treatments that included metolachor, but methyl bromide plots displayed early infestations of crabgrass and pigweed, indicating that they, too, may have benefitted from metolachlor at planting. This may also suggest methyl bromide evacuated from the top 2 inches of soil too quickly for good weed control. Oryzalin was still providing good weed control 75 days after application, and the chemical reduced the total number of all weed plants, compared to areas where no herbicide was applied. Oryzalin was still providing good control of pigweed, purslane, and Linnaria canadensis (a winter annual), a late emerging weed, 119 days after application and 54 days after the final weeding.

The methyl bromide + chloropicrin plot exhibited early infestations of crabgrass and pigweed, but control of soilborne pests, such as Fusarium, was equivalent to all other treatments. Tuber production was equivalent to the metham + chloropicrin plot. Nematodes were not present in any soil samples of any plots.

Metham + chloropicrin, with a surface application of metolachlor and oryzalin, displayed excellent early control of weeds, but control of soilborne disease pests, such as Fusarium, was not statistically different from the untreated control.

1,3-D + chloropicrin, along with a surface application of metolachlor and oryzalin, displayed excellent early control of weeds. This method also performed equivalently to all other treatments in disease pest control. In this treatment, more jumbo tubers were produced than in other treatment plots.

Research results suggest that 1,3-D + chloropicrin (83 percent/17 percent) at 35 gal/acre may be a viable replacement for methyl bromide, when combined with metolachlor herbicide at planting, followed by a midsummer application of oryzalin. This research is being continued to determine the long-term effects of these fumigant and herbicide combinations on pest control and tuber production.

Steam Sterilization in Chrysanthemums

The lack of research in floriculture has forced some growers to find their own solutions. Yoder Brothers in Alva, Florida, looked at steam sterilization to control soilborne pests, as compared to methyl bromide. "Methyl bromide is the backbone of our IPM strategy," says Patrick Crump, director of production for Yoder Brothers. "It is used after every crop rotation to prepare the soil for planting, and it is used to meet quarantine restrictions."

Yoder Brothers installed two stationary boilers (250 horsepower) with overhead pipes leading to the beds at a cost of $500,000 to treat one-third of their 1.3 million square feet of beds. The method seems to work, but is very expensive. "If we were to use this method exclusively, costs would increase by $800,000 per year," explains Crump. This amount would fluctuate depending upon labor and diesel fuel costs. "Methyl bromide is easier from a management standpoint," he says.

There are some problems facing steam sterilization. Because growers are working in an open area, the steam dissipates, which means applying it for longer periods of time. The amount of soil moisture and temperature also affects the amount of steam used and the duration of treatment.

Yoder Brothers met the first 25 percent reduction in methyl bromide availability without too much difficulty. "We achieved a 6 to 7 percent reduction by calibrating our equipment and reducing waste," says Crump.

With steam sterilization, Crump found yield to be the same or slightly better than with methyl bromide. "But the yield doesn't warrant the increased costs associated with steam sterilization," Crump warns.

Now that the 50-percent methyl bromide reduction is in effect, Yoder Brothers will have to add another phase of steam, resulting in $1.5 million in boiler expenses, to cover 1.3 million bed square feet. As of October 1, 2000, Yoder Brothers' cost to steam sterilize the soil was $1,550 per 10,000 square feet, compared to $685 for methyl bromide treatment. "Unless someone comes up with something else, we will have to use steam sterilization," says Crump.

ARS recognizes the dearth of research in floriculture and is addressing the gap. As noted in ARS Administrator Floyd Horn's letter on the cover of this issue, Congress appropriated funds in the FY 2001 budget to hire two new scientists to research methyl bromide alternatives in floriculture crops.

According to James Gilreath, "Telone products will be part of everyone's package solution. Some cut flowers are in good shape for herbicide options, but many are not." ARS' additional funding and resources may provide some relief in the long-term, but choices are limited in the short-term.

Last Updated: March 22, 2001