Volume 17 Part 1 Article 45: Flies and Dust – Epidemiology of Dry Bubble in Australia

Volume 17 Part 1 Article 45
Year 2008
Title: Flies and Dust – Epidemiology of Dry Bubble in Australia
Authors: A. Clift and A. Shamshad

Abstract:

Dry bubble, caused by Verticillium fungicola, is a major disease problem in cultivated mushrooms throughout the world. Although the basic biology of V. fungicola and the factors favouring infection are known, the relative importance of these is not. We report on a detailed examination of V. fungicola infections on seven farms near Sydney, Australia, involving several hundred crops.

An epidemiological model that ranks the known factors, taking account of variable fungicide susceptibility, pathogen virulence and farm management is proposed. The model is set up using a Bayesian belief network (Norsys®), which allows input of qualitative, as well as quantitative data. Using the sensitivity analysis module the relative importance of the various factors on initial establishment of an infection, the spread to other rooms and the management of the outbreak can be determined. Information recorded for each crop included disease and pest history, disease incidence, incidence of sciarids and phorids, assessment of farm hygiene and farm design, efficiency of physical exclusion, use of insecticides and fungicides, pesticides used in spot treatment, assessment of efficiency of spot treatment, assessment of general pesticide use. In Australia, either flies or dust were usually associated with initial infections. In situations where dust was a major factor, weak links in farm design or material flows were evident. A major factor in moving from initial infection to a major outbreak was efficiency of pesticide use, including spot treatment of isolated infections. Pathogen virulence and fungicide resistance were both important in the development of disease outbreaks.

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