I haven't had this problem myself, but this article makes interesting reading:

Here is a link that might be useful: Magnesium Deficiency in Palms

You need to check soil pH before applying dolomite. If you're already alkaline it will make it worse. That's when epsom salts (magnesium sulphate) is better as it doesn't affect soil pH. So once you know where your pH stands you can confidently pick one or the other.

And that's a great article on Mg deficiency.

It was suggested to me to use Bath Salts (Magnesium Sulfate) in my water to augment it. I mix about 1 tbsp of bath salts per gallon of rain water and I pour this around the base of my pygmies every 3 to 4 weeks. All my plants, not just the pygmies have gotten much greener since I started this practice.