the disease in contaminated potting mix, plant material and water sources. Other preventative measures include raised benches, regular testing for phytophthora dieback, and the placing of new stock in quarantine. Plants typically die from phytophthora dieback at the end of summer when the plants are under the most stress. For this reason phytophthora dieback can often be confused with symptoms of drought. Phytophthora dieback will affect a range of different susceptible plants, but will not affect resistant plant species. If the disease is suspected, a likely mode of disease transmission should be identified. The best method to confirm the presence of the disease is testing of soil and/or plant samples by a diagnostic laboratory. Control of existing Phytophthora infestations includes injecting or spraying plants with phosphite (a fungicide), using well-composted mulch, and using pre-planting techniques such as solarisation or biofumigation. Composted mulch is highly suppressive to phytophthora dieback and can prevent healthy plants getting infected. It is most important to prevent the spread of infected soil, plants or water. Infested areas can be revegetated or landscaped with resistant plant species that are not affected by the disease. Impact on avocado farming Phytophthora cinnamomi is the leading cause of damage to avocado trees, and is commonly known as "root rot" amongst avocado farmers. Since the 1940s various breeds of root rot-resistant avocados have been developed to minimize tree damage. Damaged trees generally die or become unproductive within three to five years. A 1960 study of the Fallbrook, California area correlated higher levels of avocado root rot to soils with poorer drainage and greater clay content. Management P. cinnamomi has a wide host range that makes it difficult to control the spread of disease. The greatest impact tends to be in areas with a Mediterranean climate, which receives a mean annual rainfall above 600 mm such as Southeast Asia islands and Australia. The pathogen is shown to be able to survive in plants displaying no symptoms or in tolerant plants. Some possible cultural management methods include: sanitation, raised plant beds, crop rotation, soil solarization, soil conditions, and establishing a barrier. Sanitation is crucial in management. This means using clean seed and stock as well as well-drained sandy soils with a low pH. This would also mean not allowing soil or water to move from infested areas by using clean bins and equipment, installing watertight drains to prevent surface run off, and work