I have about 11 robellini's and they grow like a weed here. It's possible it could be some minor transplant shock. We had a really dry march, and have been in a pretty bad drought up until recently as well. To up the magnesium in the soil, I fill a 5 gallon bucket up with water, and put a few teaspoons of epsom salts in it. Water your plants with it, and if magnesium is the problem, it will be corrected quickly.

Yes, we certainly did have a few dry months there. Only recently has the rain started coming on almost a daily basis up here (Lady Lake, Lake County). I actually have a few 5 gal buckets of rain water stored up (no rain barrel yet, but it's on the To-Do list), I'm assuming I can add the epson salt to one of those? I will have to mix up a bucket and give the palms a drink from it when I have a 'dry' day. As the weather looks now, I'm looking at more rain for the next week. Not that I'm complaining, mind you... Thanks for the tip.

You can certainly add epsom salts to your rain water. They dissolve readily, and this is also the quickest way to get the magnesium to the plant.

Update:
I have given the palms a drink from the Magnesium augmented rainwater and it does seem to have helped. All three plants got greener and started putting out new fronds. So thank you for that tip.

However, while two of them perked right up, one seemed to be deteriorating still. I took a closer look at the fronds and found that they were not just yellowing at the tips but that there were black, brown, yellow spots along the leaves of the fronds. I went and checked the other two and they too had the spots, but to a much lesser degree.

From researching on the net, this appears to be a fairly common fungal problem. Suggested methods of control were to remove infected fronds, which I have done, avoiding watering from the top and application of a fungicide. I have never had to purchase a fungicide for anything in my life, so I'm wondering anyone has a favorite that they like to use on their palms? Any other tips I should follow to make sure that the problem doesn't come back? I plan on taking the infected fronds to my local County Extension for verification that it is indeed just leaf spot and not something more dire. Thanks again.

I'm interested in the outcome. Please let us know what you find out. I'm in Tampa and haven't been here too long so I'm learning too.

Fungus is often the cause of problems in Phoenix roebelenii. Especially in cooler climates when they get overhead watering. In many ways that seems surprising since they come from a pretty wet climate with high rainfall.

One of the best fungicides (least toxic) is Hydrogen Peroxide (sometimes just labelled Peroxide). You can get it at various concentrations, 10% is good. You pour it into the crown and repeat until new unaffected leaves grow out. The Peroxide breaks down into water and oxygen, so no harmful residuals.