Search for what's wrong with a palm and you'll land on a wall of diseases, most of which sound alarming and most of which don't happen here. Palms are grown all over the warm parts of the country, the problems are different in each place, and almost nothing written online bothers to say which is which.
The Coachella Valley is its own case. We have date gardens around Indio and Coachella, street Washingtonias through Palm Springs, and old Canary Island date palms standing over driveways and pool decks in La Quinta, Indian Wells and Rancho Mirage. Advice written for Florida does not transfer to any of that.
So before the list of what it might be, here's the shorter and more useful list of what it almost certainly isn't.
Things people are told they have, that aren't in California
Ganoderma butt rot. This is the one that produces a hard shelf-shaped conk on the lower trunk and has no cure. It's a Florida, Georgia and South Carolina problem. University of California's page on landscape palm diseases doesn't list it at all.
Lethal bronzing. Also called Texas Phoenix palm decline. Real, fatal, and confined to Florida and Louisiana. Not California.
Bayoud disease. The one that gets mentioned in every article about date palms. It's in Morocco, Algeria and Mauritania. It has never been established in the United States, which is precisely why the rules about moving date palm material are as strict as they are. That matters more here than almost anywhere else in the country, because the date industry sitting between Indio, Coachella and Thermal is what those rules exist to protect.
Diamond scale. This one is in California, so it's the easiest to get wrong. It hits California fan palms, but UC says it rarely occurs in arid regions such as the deserts of Southern California. That's us. It's a coastal and valley problem, and a quote for it on a Palm Desert or La Quinta property deserves a question.
Pink rot. Also real here, also mostly not ours. UC notes palms in cool humid coastal areas are more susceptible than those in warmer, more arid, inland sites.
If you've been quoted for treatment on any of those, ask what it's based on.
What actually kills palms here
Fusarium wilt, and the chainsaw that brings it
This one is real, it's in California, and it's nearly always our fault as an industry rather than bad luck.
UC is blunt about how it moves. In the landscape, Fusarium wilt nearly always spreads on pruning tools, especially chain saws. The fungus goes in through cut petioles. Contaminated sawdust can drift as far as a hundred feet.
There's no cure and it's nearly a hundred percent fatal. Prevention is the whole game, and prevention means the saw. This is a fair thing to ask any crew before they start: what do they sterilize between palms, and when did they last do it. An arborist who trims palms for a living should have an answer ready.
What you'd see is the leaflets on one side of a frond dying while the other side stays green, then more fronds going the same way. The dead fronds turn yellow, then brown, and hang on the palm rather than dropping.
That one-sided pattern has a look-alike. Petiole and rachis blight does the same thing, and the way UC separates them is by how much of the canopy is involved. With the blights, typically only a few leaves are diseased. With Fusarium, it's many leaves. That distinction is worth a lab test before anyone takes a palm down.
Sudden crown drop, and why it gives no warning
This is the one that should change how you think about an old Canary Island date palm near a driveway. There are a lot of them in this valley, planted decades ago along resort frontages and in the older neighborhoods of Palm Springs and Rancho Mirage, and they are now exactly the age where this matters.
UC says sudden crown drop primarily affects Canary Island date palms and, to a lesser extent, date palms. Here's the part that matters. The canopy of leaves typically remains green and healthy, and the outer layer of trunk tissue appears normal and intact.
In other words the palm looks completely fine, right up until the crown comes off. The decay is inside the trunk. You can't see it from the ground, and the healthy-looking green top is not evidence of anything.
There's a rough field check. Tap the upper trunk with a rubber mallet. Solid wood gives a sharp, resonant tone. Decayed wood gives a dull thud. It isn't proof either way, but it's the reason arborists knock on trunks, and it's why we won't send a climber up a palm that sounds hollow.
The beetle that's actually native here
The giant palm borer is a Coachella Valley insect. Not an invader, not new. Its larvae live inside the trunk for years and the adults leave round exit holes roughly the size of a quarter in the upper trunk.
Those holes mean the infestation has been there a long time, since the larvae feed for several years before emerging. Enough of them weakens the trunk to the point that it can snap in wind, which is worth thinking about in a valley that gets the wind we get through the San Gorgonio Pass. There's no treatment. What you can do is not buy a palm with exit holes already in it, and keep the ones you have in decent health.
The thing that isn't a disease at all
A large share of the declining palms we look at across the valley aren't infected with anything. They've been trimmed too hard for years, they're short of potassium, and the trunk is narrowing near the top as a result.
It looks like a disease. It gets treated like a disease. It's a maintenance problem, and it's the most common thing we find on a palm here.
How to tell whether it's urgent
One question sorts most of it. Is there a healthy green spear at the top, and does it stay put when you tug it?
A palm has one growing point. There are no dormant buds and no second chances. If the spear pulls out easily and the base smells rotten, the palm is finished no matter how green the outer fronds still look.
If the spear is firm and new growth is coming, most of what's wrong is workable, though slowly. Palms don't repair damaged fronds. They only put out better new ones, and that takes years rather than weeks.
When to call a palm tree doctor
Call quickly for a dead or loose spear, a crown that's tilting, a trunk that sounds hollow, or a Canary Island date palm near anything you'd mind it falling on.
Call at a normal pace for one-sided frond death, a trunk that's narrowing near the top, or a canopy that has fewer fronds every year.
And if someone has told you your palm has a disease with a dramatic name, it's worth ten minutes to find out whether that disease occurs in this state at all. Sorting a real problem from a sales pitch is most of what an arborist does, and it's the same habit that separates a leaf pest on a ficus hedge from something that needs spending on.
We work out of La Quinta and cover the valley end to end, Palm Springs through Indio. If you want someone to look at a palm before you agree to anything, that's what the Coachella Valley office is for, and a tree doctor visit costs a lot less than a palm. A palm tree diagnosis separates the three or four things that actually occur here from the long list that does not, and a tree health assessment puts the answer in writing before you spend on either treatment or removal.