PHYTOPHTHORA CITRICOLA (SAWADA) - CAUSE OF AN IMPORTANT SHOOT ROT OF RHODODENDRON AND AZALEA
The disease cycle is still not clearly unterstood. The fungus survives (Oospores) in the soil, enduring longer frost periods.
The infection takes place between 10 °C and 30 °C, primarily at the upper parts of the shoots. This indicates that the spread of the disease may be due to zoospores, which are transported to the plant's surface by drops of irrigation- or rainwater carrying contaminated soil particles. In order to be successful, control programs in commercial plant productions have to combine sanitary steps and spraying programs using Fosethyl as a fungicide.