King Sago Palm Trunk Rot

Phytophthora

• King Sago palm trees are susceptible to root and crown rots brought on by the pathogen Phytophthora. A number of species of this fungus exist, and all produce a rotting of the trunk of the tree and its branches and roots. The fungi enter the tree through its root system and the foliage may turn yellow as the fronds are denied water and nutrition due to the root's inability to properly absorb them.

Symptoms

• The rotting taking place inside the trunk is displayed by the streaking, staining and formation of cankers -- open wounds -- on the bark of the King Sago palm. A blackish, red sap oozes from the areas of infected tissue with the wood beneath the bark also appearing a dark brown or gray color. As the disease worsens, branches begin to die back, the growth and vigor of the specimen diminishes and the eventual death of the palm is likely.

Management

• Phytophthora fungi live within the soil for many years so even removal of the tree or containment of the disease does not eradicate it completely. Infected trees should be removed and destroyed with resistant plants placed in the space. To prevent transfer of root rot, mechanical devices like pruning shears and shovels should be utilized. Fungicides help to limit the presence and damaging effects of the disease, but the ideal prevention is to manage the occurrence of Phytophthora fungi.

Cultural Practice

• The likelihood of a King Sago palm developing trunk rot is minimized through proper cultural practices. Phytophthora fungi only thrive if the surrounding soil is exceptionally moist. Gardeners should avoid planting the tree in earth that is poorly drained or susceptible to periods of standing water. Overwatering of the palm should be avoided and the planting of resistant cultivars is possible. In addition, new Sago palms should be planted in mounds of dirt at least 8 to 10 inches high.