Need help with chlorotic king palms
Two years ago we moved to a new home with deep green, lush king palms in the front yard and very chlorotic palms of the same species in the back yard. They have half as many leaves as the ones in the front. The leaves are mostly yellow with brown tips and dry prematurely.
Since then I have tried many things.
A year ago, we dug the soil 2 ft deep and mixed in organic compost. Increased the water. All the plants came back but the palms remained sick.
This spring, I treated the soil again with chelated iron in the recommended dosage and also osmocote. No changes in the palms, however, some plants around them burned with all the fertilizer.
I don't know what else to do... It puzzles me that I have the other healthy king palms in the same soil... My garden is heavily planted so I am considering injections at this point to avoid harming the nearby plants with too much feed. Please help?