Potassium phosphonate controls root rot of Xanthorrhoea australis and X minor caused by Phytophthora cinnamomi

Soil drenches and foliar sprays of potassium phosphonate protected glasshouse-grown Xanthorrhoea minor and X australis against root rot caused by Phytophthora cinnamomi. Three concentrations of potassium phosphonate (0.1, 1.0 and 5.0 mg/mL), applied by both methods, reduced the severity of root rot symptoms and increased plant survival rates. Soil drenches were more effective than foliar sprays. The highest rate of