Q.What is the fastest and surest way to control this desease please ?
THIS PALMS WERE PLANTED ABOUT 5 YEARS AGO, THEY GREW VERY WELL UNTIL LATELY THEY STARTED SHOWING SOME PIN HOLES IN THE TIPS OF THEIR LEAVES AND STARTED TO SPREAD ALL OVER THE OTHER LEAVES, I WAS SUGGESTED TO USE MANZATE BUT DID NOT WORK.
Certified GKH Gardening Expert
This is likely a manganese deficiency. This will cause what is called frizzle top, and eventually the death of the tree if not cared for. The solution is simple. MANGANESE sulfate. Not magnesium, but manganese sulfate.
This will correct the issue, and prevent the death of the tree. This article will help: https://www.gardeningknowhow.com/houseplants/palms/frizzle-top-on-palms.htm