Options to Methyl Bromide for the Control of Soil-Borne Diseases and Pests in California with Reference to the Netherlands
Abstract
Methyl bromide is a broad-spectrum soil fumigant. It is widely used in California and other parts of the world to control soil-borne diseases and pests of economically important crops such as strawberries and nursey stock. The fumigant is applied generally before planting in combination with chloropicrin. Mixtures of these two fumigants combine the greater soil penetration of methyl bromide and higher fungal toxicity of chloropicrin.
Methyl bromide was listed in 1993 by the Parties of the Montreal Protocol as an ozone-depleting compound. Because methyl bromide has an ozone depletion potential larger than 0.2, this fumigant was placed under the U.S. Clean Air Act of 1990. Under this Act, the domestic production in 1994 will be frozen at 1991 levels. In addition, the importation and production of methyl bromide will cease by the year 2001.
In California, methyl bromide is widely used to control soil-borne diseases and pests of economically important crops. The largest use of methyl bromide is for the treatment of fields before planting of strawberries, followed by soil treatment by the nursery industry. It is essential that environmentally sound and economically feasible alternatives are in place and available to California farmers and pest control advisors well before the year 2001 to meet the mandate specified in the U.S. Clean Air Act. Based on an extensive review of relevant scientific publications, proceedings of international conferences, and consultation of United States and Dutch scientific experts, the California Department of Pesticide Regulation evaluated chemical and non-chemical options to methyl bromide.
The largest use of methyl bromide in the Netherlands is for greenhouse production of strawberries, several vegetable crops, and cut flowers. Because of concern for public safety and for air and groundwater quality, the Netherlands decided to gradually phase out methyl bromide soil fumigation from 1982 through 1992 by adopting new pesticide policies and farming systems.
No single synthetic chemical or non-chemical option to methyl bromide in the broad-spectrum of field applications for which it is currently used could be identified. There are partial synthetic chemical and non-chemical options and all can be used for the development of integrated pest management and integrated farming systems. Integrated pest management and integrated farming systems could be a viable strategy to replace the use of methyl bromide and concurrently reduce the use of and dependence on synthetic pesticides. However, due to the availability of effective synthetic pesticides, in specific the broad-spectrum soil fumigants like methyl bromide, there has been no need for the development of integrated pest management and integrated farming systems. This may change if all broad-spectrum synthetic pesticides are phased out. Government, university, and agricultural industry cooperation will be needed for the development of integrated pest management and integrated farming system approaches.