The California floriculture industry is a large and important component of the state's agricultural economy, with a reported value of about $1 billion in 2004 [U.S. Department of Agriculture–National Agricultural Statistics Service (NASS)]. In California, floriculture crops are grown on ≈2900 acres of covered land and 8000 acres of open ground. Cut flowers and bulbs are high-value crops that require large expenditures of capital to establish and bring to commercial maturity. The cut flower and bulb industry has relied heavily upon the use of methyl bromide/chloropicrin (MBC) as a key soil treatment for crop production. It has been used as a preplant fumigant to control soil-borne fungi, nematodes, bacteria, and weeds, as well as to kill the soil-borne remnants of previous crops (e.g., bulbs) that can sprout and contaminate the next crop.
The ozone depletion potential of methyl bromide has resulted in the phase-out of this chemical except for a few specific uses. Without methyl bromide, or an equally efficacious alternative, cut flower and bulb producers face potentially serious production limitations. It is extremely important that alternatives be developed to manage the pests formerly managed by methyl bromide. However, because of the diversity of the crops represented and the comparatively small acreage involved, the floriculture industry has received inadequate methyl bromide alternative research compared with other crops. Furthermore, although it is too soon to know, there are concerns that floricultural crops will not compete favorably against large-acreage crops for alternate materials like 1,3-dichloropropene, which have “township caps” limiting their use within geographical areas.
Propargyl bromide is one of many compounds being considered as a methyl bromide alternative (Allaire et al., 2005; Ma et al., 2001; Schneider et al., 2006). In 1957, Dow Chemical Company was granted a patent for propargyl bromide as a soil fumigant. However, it subsequently was taken off the market because of unstable handling characteristics. The handling characteristics of propargyl bromide continue to be a challenge for its commercialization. However, its physical properties make it attractive as a soil fumigant because it moves readily through soil, has a short soil degradation time, has strong biocidal properties, and does not have ozone-depleting characteristics (Yates and Gan, 1998). In the midlate 1990s, it was suggested that propargyl bromide should be revisited as a viable methyl bromide alternative, and the U.S. Department of Agriculture decided to sponsor research that would evaluate the efficacy and environmental fate of the chemical used as a soil fumigant. This research was undertaken as part of the efficacy testing and sought 1) to evaluate propargyl bromide against a diversity of soil-borne pests, 2) to determine propargyl bromide efficacy in three different geographical environments, and 3) to compare propargyl bromide with MBC, iodomethane, and metam sodium.
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