Volume 8 Part 1 Article 75: The Use of Methyl Bromide in Disease Control

Volume 8 Part 1 Article 75
Year 1972
Title: The Use of Methyl Bromide in Disease Control
Author: J. Tunney


It is now widely accepted that after-crop pasteurization is a necessary procedure in the prevention of disease build-up in modern mushroom plants. By killing pests and other disease organisms which infect the crop in situ, the possibility of cross infection is eliminated and this is particularly important in the U.K. in minimizing crop losses due to virus, nematode and insect pests – afflictions which if allowed to contaminate new crops via trays and woodwork, cause severe loss of crop. Traditionally, heat is used for this purpose and if correctly applied is completely effective, but since 1968, and largely as a result of work done at the Glasshouse Crops Research Institute, methyl bromide fumigation has been available to U.K. mushroom industry and it is the purpose of this paper to inform this congress of this alternative to live steam in after-crop pasteurization.

The toxicity of methyl bromide to the mushroom pests and pathogens has been established by Drs Hayes and Hussey of the GCRI, but an equally important attribute of the gas is its stability. It is not highly absorbed by materials used in mushroom growing. It can therefore penetrate easily during treatment and escape rapidly on ventilation. Because of human safety and the requirements for correct fumigation, special procedures are adopted and in the U.K. only persons trained in methyl bromide fumigation procedures are allowed to operate this service. Methyl bromide is applied either as a fine spray of liquid through a series of nozzles located within the structure, or as a gas from a heated vaporizer from which it is distributed by a polythene ducting with outlets along its length. Experience has shown that the latter method favours a more rapid penetration and generally a more uniform distribution, an important requirement which occasionally presents difficulties in the cold months of our U.K. winter. Careful use of fans aids the distribution in both methods of application, but much care is needed to avoid leakage during fan operation.

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