Everything looking like hell in one area

In one area of my farm, I've been having some problems with all of my zingiberales. I've not been able to identify what the problem is, so I'm hoping you guys can help me. Nothing has ever been particularly happy in this spot, but I didn't notice these leaf problems until about a year ago.

Location: Hilo, Hawaii
Environment: Humid and rainy
Elevation: 1000 feet/300 meters
Soil pH: 5.2

Things I've tried:

• Sprayed leaves (including undersides) with Reliant phosphite-based fungicide
• Removed affected foliage
• Currently applying fertilizer and micronutrients to address potential deficiencies (have not fertilized these plants before, but frequently mulch)

As an example, here's Calathea 'Orange Beads' in the area. Other plants in the area exhibit similar characteristics.

Thank you,
Josh Usovsky

It looks like it might be a nutrient deficiency. That could be why this is happening in one area.