Provides detailed results of long term studies of diseases of cotton found in the major cotton growing areas of northern New South Wales and southern Queensland. Diseases investigated include bacterial blight (Xanthomonas campestris), verticulum wilt (Verticulum), seedling diseases, black root rot (Thielaviopsis basicola), alternaria leaf spot (Alternaria macrospora) and Vesicular arbuscular mycorrhiza (VAM). Also discussed are investigations into the factors associated with fibre damage in cotton.

Gives an overview of the most relevant sessions of the conferences for the study of the control of diseases in cotton in Australia. Also included are a copy of the paper presented at the Cotton Disease Council Meeting, entitled 'The distribution, importance and control of diseases of cotton in Australia', and a copy of the contents of the proceedings of the 1992 conferences.

The effects of 10 different foliar diseases on the photosynthetic and transpirational activities of five annual and three perennial crops were examined under field conditions. The following pathosystems were investigated: leaf rust, powdery mildew, and Septoria tritici blotch of wheat; rust of corn; downy mildew of cucumber; Alternaria leaf spot of cotton; powdery mildew of pepper Pestalotia of mango; powdery mildew of peach; and powdery mildew of grapes. Visual estimates of infection do not always indicate adequately the effect of a pathogen on these physiological processes. Three different patterns of host response were observed in diseased leaf area relative to disease-free leaf area. The decrease in rate of photosynthesis or transpiration was a) proportional, b) proportionally greater, or c) proportionally smaller than the corresponding reduction of healthy leaf area due to disease. Host responses were not always related to the systematic group of either the host or the pathogen. The pattern of responses and the amount of reduction in photosynthesis and/or transpiration rates were, however, related to the type of trophic relationships. This article provides regression models that may be used for incorporating the effects of various foliar diseases to crop growth simulators.