reasons for sago palm leaves turning yellow

Question

what fertilizer is best for this problem

Answer 1

Palm Pro label:
https://www.domyown.com/msds/GROWTHPRODUCTSPALMPROLABEL.pdf

Use 1 to 2 oz ounce per gallon of water as a soil drench and foliar fertilizer. You can foliar fertilize every week for two or three months for a faster green-up, with the solution in an ironing-type spray bottle. Spray top and bottom of leaves.

Answer 2

I have used this one for my customer's palms and cycads, spring and fall applications, with good results. It has a lot of goodies in the formulation:
https://www.domyown.com/palm-pro-12-12-with-60-srn-p-17615.html

Here's another possibility, but I have no personal experience with it:
https://www.domyown.com/dr-earth-organic-palm-tropical-hibiscus-fertilizer-p-9489.html

This article also discusses important water management factors:

https://www.gardeningknowhow.com/ornamental/trees/sago-palm/sago-leaves-turning-yellow.htm