Control - There are no fungicides which are available for this pathogen on hibiscus. When weather conditions are optimum, plants should be examined daily and old flowers removed and discarded to reduce spread of spores to adjacent plants. Symptoms - This condition is usually not a problem once plants are established in the landscape. In containers, plants are small, unthrifty and can give the appearance of lacking fertilizer. Roots should be examined to determine their health.
Rotted roots are mushy, wet and disintegrate when handled.
They are also usually brown to black. Since these symptoms can be caused by nematodes as well as pathogenic fungi a laboratory diagnosis is required for best course of treatment. Control - Diagnosis of the causal organism is the most important step toward control of root diseases. Rust disease is easily recognized because of the yellowish-tan pustules which occur on leaf undersides. The spots first appear white or light yellow when viewed from the upper surface.