Yellowing stems on sago palm
This is a Cycas revoluta, Sago Palm. The yellowing could be a nutrient deficiency. Sagos growing in a landscape need to be fertilized three to four times a year, March through September, with a special fertilizer for palms, available at most garden centers.
Most of the nutrients in the fertilizer should be slow release. Follow the directions on the label for best results. Broadcasting the fertilizer underneath the canopy works best for the plant. You may need to rake away mulch so the fertilizer reaches the root area. Irrigation directly after application of fertilizer, ¼ inch of water, increases the potential of nutrients reaching the root area efficiently. Move the mulch back over the root area. Remember, mulch should never be touching the trunk of any tree or shrub.
It is best to keep palm fronds on the plant as long as possible. In fact, remove the fronds only when they are completely brown. As long as some green remains on the frond, then it has the capability of producing food for the plant. Removal of too many fronds causes the plant additional stress.