Sago palms are vulnerable to disease, infestation, nutrient deficiency and environmental damage. Though generally considered hardy plants, they may fall prey to any of these problems in certain conditions. Care must be taken to maintain the plants and provide them with the requirements for healthy, vigorous growth.
A fungal disease called Phytophthora can cause root or crown rot. This fungus thrives in wet, poorly drained soil. Phytophthora can be treated by moving the palm to new soil, cutting out the rot and treating the palm with a fungicide for use on cycads (plants with a stout woody trunk and a crown of large leaves).
Appearing as tiny white spots on the plant, the fungal juice is fed on by scale and mealybugs. To get rid of these pests, their protective layer should be dissolved. Insecticidal soaps and mild alcohol solutions are effective treatments, but they may take long to work.
If sago palms are planted in soils with an unsuitable pH level, their leaves may yellow because of a lack of manganese. If correcting the pH level doesn't improve the condition, adding manganese to the soil is advised.
The sago palm's leaves can be affected by extremely high or low temperatures. Removal of damaged leaves generally solves the problem if the area where new leaves emerge is undamaged.