| Abstract: | Rust (Tranzscheliu discolor) is the most important disease of French prunes in New South Wales (NSW), Australia. Infection by this fungus occurs only when leaves are wet. The length of time for which the leaves are wet and the temperature during such periods are major determinants of whether infection occurs and its likely severity. The use by prune growers of new rust management strategies depends on knowledge of infection events and therefore requires ready access to environmental data from orchards. To satisfy this need, microprocessor-based device called a Prune Rust Infection Predictor (PRIP) was developed. The instrument measures air temperature, rainfall, and the presence or absence of free water tree canopies. Measurements are taken at 5-min intervals during wet periods. The instrument calculates whether or not conditions have been suitable for rust infection and potential severity of infection. The system has been operated by advisory staff of NSW Agriculture Fisheries since the 1988/1989 growing season. Potential infection period and related environmental data are collected by personal computers via permanently installed telephone lines from PRIPs located within prune orchards. Prune growers are then advised by recorded telephone messages and given appropriate disease mangement advice. Cumulative potential infection period values are used to provide a prognosis of current-season rust epidemic severity. An expert system is also being developed to assist growers in making decisions on specific rust management options. |
