I have several sago palms in my yard. In early spring, I noticed white spots covering the trunk and then on to the leaves/fronds. I had read somewhere that coffee grounds would fix this problem. I tried that, trimmed the palm and saw improvement in the problem. Then in mid summer, I lost one of the sagos, undetermined cause. Now, the white spots are appearing on the same sago as well as other sagos in my yard, even the small ones I had potted for future use. I certainly don't drink enough coffee to fix this. What do I do to salvage may sagos, two of them are 9 years old, the others younger.
White Spots on My Sago Palms
Certified GKH Gardening Expert
It could be scale or mealybugs. I would treat the plants with neem oil. This is organic and safe for people and pets and very effective on these pests. These articles will help you: