What Is Wrong With My Sago Palm?

Is there a dark vertical stain or sore on the trunk possibly with black or red-black oozing sap?

Do the leaves have spots or blotches?

Do the leaves and stems have white, cottony clusters on them?

Are the leaves covered with small bumps?

Phytophthora root rot is a fungal disease that occurs occasionally in compacted soils. These soil-borne pathogens can cause a tree to die within a few years if not treated. Treating phytophthora root rot disease is possible by using fungicides containing the ingredient fosetyl-al. Follow label directions.

Your plants are suffering from fungal leaf spot. These can come from several fungus diseases, causing spots to occur on foliage. Spots may enlarge rapidly, especially in wet weather. Destroy infected leaves or plants. Spray plants with sulfur to prevent the disease from spreading, especially if the weather is wet. Spray between rains. Prevent problems by thinning plants to provide good air circulation.

White, cottony clusters on leaves and stems are caused by mealybugs. These tiny insects are covered with a fluffy white coating. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations.

Leaves covered by small bumps are caused by scales. These tiny, shelled insects often feed on the undersides of the leaves, causing an unhealthy appearance with yellowish blotches on the upper leaf surfaces. Scrape off minor infestations with your fingernail. Prune out badly infested growth, or use a soft brush and soapy water to gently scrub the scales off the stems. Control scales by spraying insecticidal oil during the growing season.

Sago palm yellowing is common in older leaves as they get ready to drop to the ground and make way for newer leaves. If you have ruled out scale and mealybugs, yellowing in younger leaves may be caused by a lack of manganese in the soil. Applying manganese sulfate powder to the soil two to three times per year will correct the problem.