One of my washingtonia filifera suddenly displayed yellowing fronds. I have more than a dozen mature specimens around my plot and none have ever done this.

Weather has been normal. Gets 20-30 gallons of water 2X a week (15gph emitter, plus plants near it with 2gph emitters). It sits up on a hill of its own, so drainage is excellent.

The spring fronds still good and healthy, the center spears appear fairly normal, but the middle fronds are shocking pale yellow.

Plenty of its friends get much more water, and some much less water. Some are in sand, some in clay. None have ever done this. The washies have always been pretty tolerant of whatever circumstances they lived in here.

I haven't a clue where to start. I hesitate to assume chlorosis and put iron and acidifier down. I've considered dissolving some plam fert with magnesium and doing a soil drench. None of my pindos have iron issue though and they are supposedly more sensitive. Perhaps this is a single location issue? I've watered the nutrients away?

I know young fronds take a moment to green up. But this is very minor and only between frond pleats in my experience. Every other filifera I have is deep green right now, inside and out.

Does anyone have any tips?

St George, UT. Alkaline soil.

Hey all. Hoping to take action before its too late, if there is such a thing. Google and AI are useless.

Don't know which path to take and fear making it worse.

Please help me move to the right topic if I have this miscategorized.