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.

I'm not sure if I've done something wrong, but I'm really surprised to see zero feedback.

These fronds are now completely dead.

I ordered in Southern Ag Palm Nutritional Spray ( manganese, iron etc) in hopes of helping the palm. Administered about 5 days ago as a soil drench. Center spear has some green but unsure if it will stay that way. It didn't help the spears that were starting to yellow - they kept dying.

I would still really appreciate advice.

Ouch!

Sorry to hear and see the pictures!

Give a tug on the browned leaves; if they pull out, get some hydrogen peroxide and dump it straight into the hole, repeat and pray. It looks like you might have a fungus in the growing point.

These are very tough palms! Make sure it has adequate water to get it established (10 gallons at a time, twice a week). Keep the faith - it will recover.

aztropic

Mesa, Arizona

The idea that it is one of several washies and the only one to have this issue says its likely a site problem. THe newer parts of the crown drying up like that are consistent with a fungal infection as Dave said. THe spear may pull with a tug,dont be afraid to tug on it repeatedly, thge center is dead. Need to get peroxide and fungicide down the spear hole ASAP with no delay.

Thank you for the feedback.

To clarify, these have been there 3 years. They are pretty established with a foot of trunk growth since planting.

We have had zero rain since March, until 3 days ago.

How would fungus appear in the heart with no moisture?

I will go try and tug on the dead fronds.

None of them will budge. They are every bit as anchored as the healthy fronds. I pulled as hard as I could with leather gloves until I ripped them with the armor, and it will not move.

To clarify, the center-most spear is green. Whether it will stay that way remains to be seen. But its solid and I cannot pull them at all. More images attached here.

Not to bury the update above, but I noticed its nearest neighboring palm about 20 feet away, has a leaning center with some abnormal yellow and at least one frond is opening strange. Its hard to show in pictures, but the key point is that all the spears are acting a bit floppy. And lean.

Nothing like the top hill but also not normal for this palm in the past.

Its in a very different situation (a bit more standing water when irrigated, block wall right next to it) versus original palm of this post which is on a solo hill. Water just runs away.

Could it still be related?

Are these both just somehow deficient because of some random soil difference on this side of my yard?

Hmmm

Sometimes desert situations really get bad nutrient deficiencies too; I don’t know a lot about that.

2 minutes ago, DoomsDave said:

Hmmm

Sometimes desert situations really get bad nutrient deficiencies too; I don’t know a lot about that.

We have high alkaline soil here. I have a maple that isn't gonna make it because I cannot keep up with the iron and soil acidifier treatments as it grows.

At this point my theory is iron and manganese deficiency from even higher pH due to the block wall, and all the rocks inside the fill dirt on the hill one. Maybe they took tough soil and made it worse. Seems weird they are both doing it with such different sites, but, if the alternativeis fungus, I really can't imagine how it could take hold when its been 90F-105F for 3 months with <5% humidity and zero rain until this week (well after all this began). Our weather mirrors Vegas.

The rest of the palm fronds are unchanged on both specimens. And both have perfectly green center spears. I just dont know if those center spears will also yellow as they try to grow out.

I gave a full soil drench of the fertilizer I listed above (Southern Ag Palm Nutritional Spray) a week ago. Plan to do it again in another week per the bottle instructions.

Is there anything else I should be doing?

You say it is an alkaline soil. Do you know the pH? Have you had it tested? Also, what is your water’s pH? Severely out of balance pH situations can cause deficiencies where some nutrients become unobtainable to the palm. It is possible that they looked fine before but actually had deficiencies that you didn’t notice. Have you changed anything in your care routine recently?

38 minutes ago, Bradgray said:

We have high alkaline soil here. I have a maple that isn't gonna make it because I cannot keep up with the iron and soil acidifier treatments as it grows.

At this point my theory is iron and manganese deficiency from even higher pH due to the block wall, and all the rocks inside the fill dirt on the hill one. Maybe they took tough soil and made it worse. Seems weird they are both doing it with such different sites, but, if the alternativeis fungus, I really can't imagine how it could take hold when its been 90F-105F for 3 months with <5% humidity and zero rain until this week (well after all this began). Our weather mirrors Vegas.

The rest of the palm fronds are unchanged on both specimens. And both have perfectly green center spears. I just dont know if those center spears will also yellow as they try to grow out.

I gave a full soil drench of the fertilizer I listed above (Southern Ag Palm Nutritional Spray) a week ago. Plan to do it again in another week per the bottle instructions.

Is there anything else I should be doing?

If you have had no rain, I suspect watering issue, not fungus. Fungus typically occurs from being wet, as in overhead irrigation. You may just have smaller areas where the irrigation water runs off and now that there is no rain the moisture is not spreading in the soil. No moisture means no feeding on nutrients Concrete block wall never caused a problem for me in Arizona's sonoran desert. But the soil there was alkaline. Really high calcium soils cannot be practically treated for pH. If your soil test does not call your soil calcareous, pH can be shifted safely and gradually with sulfur pellets which gradually break down with microbe action and will neutralize calcium if you add enough. I added a few hundred pounds over 3 years and didnt see any evidence of a pH caused Iron deficiency after that. You could temporarily shift the soil pH by adding some dilute Epsom salt solution as a short term emergency action. Get a water can and put down 10 gallons of 1 heaping teaspoon every 2 gallons. This will alter the local soil pH temporarily so micronutrient uptake can occur. All the symptoms, actions, and observations considered, I would do the Epsom salt add some chelated iron fi that is in the nutritional spray. Bioavailability of micros at soil 8.5pH has copper, Zinc, boron, manganese, phosphorus, and most of all Iron are not very bio available. Even at pH 8 only phosphorus become sufficiently bioavailable. There is a lot of potential there for complex deficiencies if your soil is pH 8-8.5. Lack of water will aggravate a soil pH problem further by reduced feeding. The palm nutritional spray should be added just after the Epsom salt pushes the pH down (temporarily). I would get a soil test for calcium and pH and start reading on soil pH amendments. A short, fast pH adjustment by say Ammonium sulfate may shock the palm and it could get a setback. Sulfur is the safest way but takes time. Epsom salt is more mild in shifting pH than ammonium sulfate or ammonium nitrate though it adds the Mg which is probably a good thing in high calcium coil as palms prefer a low Ca to Mg ratio of about 3.

1 hour ago, Johnny Palmseed said:

You say it is an alkaline soil. Do you know the pH? Have you had it tested? Also, what is your water’s pH? Severely out of balance pH situations can cause deficiencies where some nutrients become unobtainable to the palm. It is possible that they looked fine before but actually had deficiencies that you didn’t notice. Have you changed anything in your care routine recently?

Our municiple supply is 7.3-7.6 depending.

Soil was tested as 8.1 three years ago. But that was a spot in my front yard; I have nearly an acre so I don't know the distribution across all soil I have, nor how it changes with depth.

Given the known averages, feels like a safe assumption.

I'm agreeing with sonoranfans; I think irrigation has washed away usable nutrients.

The fertilizer I used has water soluable iron, manganese and magnesium. Hopefully that helps it recover. Epsom salt worries me a bit; I've read the line between enough and too much is really narrow.

They look a little nutrient deficient, but I have never heard of a Washingtonia being affected negatively by alkaline soil. Their native soil is alkaline.

10 hours ago, rprimbs said:

They look a little nutrient deficient, but I have never heard of a Washingtonia being affected negatively by alkaline soil. Their native soil is alkaline.

this is true alkalinity is not an issue for FIliferas. They are also not so dependent on nutrients. Watering seems to be the issue.

23 hours ago, Bradgray said:

Our municiple supply is 7.3-7.6 depending.

Soil was tested as 8.1 three years ago.

I think those numbers are fine and probably not your issue. I wish I had water numbers like that. Our water is typically around 9 now because people prefer alkaline water vs acidic so the water authority treats it to raise the pH. I think my soil is 8.5ish.

@Bradgray check out the PM (Private message) I just sent you.

dave

13 hours ago, sonoranfans said:

this is true alkalinity is not an issue for FIliferas. They are also not so dependent on nutrients. Watering seems to be the issue.

Do you mean its being overwatered? Or that its simply washed away nutrients because of the aforementioned irrigation?

St George is Vegas minus a few degrees. Excessively hot and dry. Edge of Mojave Desert, where it contacts Colorado Plateau. Great Basin is our north border. Unique banana belt in Utah (I've seen a few members post from here).

If I didn't do supplemental watering, they likely wouldn't make it. Even my yuccas are on 1gph drips.

I run the filiferas on 15gph drips, for an hour, twice a week. Seems like a reasonable amount of water for our area.

Am I mistaken?

11 hours ago, Bradgray said:

Do you mean its being overwatered? Or that its simply washed away nutrients because of the aforementioned irrigation?

St George is Vegas minus a few degrees. Excessively hot and dry. Edge of Mojave Desert, where it contacts Colorado Plateau. Great Basin is our north border. Unique banana belt in Utah (I've seen a few members post from here).

If I didn't do supplemental watering, they likely wouldn't make it. Even my yuccas are on 1gph drips.

I run the filiferas on 15gph drips, for an hour, twice a week. Seems like a reasonable amount of water for our area.

Am I mistaken?

In arizona I can tell you drip irrigation with a timer is the difference between life and death for some young palms unless you dote on them. The dead center is now a very good media for fungus to grow and expand. Whether the center is dead from lack of water or from too much, dead material is not protected from pathogens by plant defense. Never water these palms from the overhead, just water the ground around them and this is particularly important when you have dead new growth. Green material is generally protected by the plant chemical defenses(terpenes and enzymes) unless its catching water or moisture in a hole, like the bud. The leaves going straw color is dead and that risks the dead growth will retain water to assist fungal growth and the bud is not protected from fungal attack under those conditions. I'd keep pulling on the dead newest growth and get the hydrogen peroxide 3% on the bud area every couple days. I also use daconil fungicide as a follow up 2-3 hrs after the peroxide. If that soil there tends to always be damp, it may also be enabling the fungal attack. If the soil is dry at 6-8" depth just water it consistently but for a longer period, 90 mins. If you don't have a timer consider it, as you will not be able to forget watering. It might be that site has unusual drainage, you should know with a drainage test nearby(3' away).

On 7/20/2026 at 7:12 PM, Bradgray said:

Do you mean its being overwatered? Or that its simply washed away nutrients because of the aforementioned irrigation?

St George is Vegas minus a few degrees. Excessively hot and dry. Edge of Mojave Desert, where it contacts Colorado Plateau. Great Basin is our north border. Unique banana belt in Utah (I've seen a few members post from here).

If I didn't do supplemental watering, they likely wouldn't make it. Even my yuccas are on 1gph drips.

I run the filiferas on 15gph drips, for an hour, twice a week. Seems like a reasonable amount of water for our area.

Am I mistaken?

Once they are established you can get them by on almost nothing, but the first year you need to water a bit until they get established.

After some wrestling with AI, I had the idea to upload the following image. Gemini said something about the stems and I realized I had discoloration there.

This is the image of my palm I sent it (it loaded at the bottom for some reason)

And it came back with a definitive diagnosis that I've since peer reviewed and I think its actually right. Incredible.

Output::

"What you are looking at is not a root drench issue, and it is not a standard manganese deficiency. This is a textbook, high-resolution view of a severe Petiole / Rachis Blight (a fungal vascular disease caused by pathogens like Cocoicola, Serenomyces, or Diplodia).

Looking closely at the image reveals the exact mechanics of what is happening to your tree:

Image Analysis: What the Photo Shows

1. The Longitudinal Brown Bands: Look at the distinct, dark reddish-brown lines running parallel right along the inner grooves of the yellowing stem. Those stripes are active fungal decay invading the petiole's internal vascular tissue (xylem).

2. The Scorched "Blistered" Margins: The dark, ragged, paper-like crusts on the sharp edges of the petiole (where the spines/teeth meet) show where the fungus has literally killed the outer tissue and choked off water to the rest of the frond.

3. The Active "Bleach Zone": Notice how the tissue is a sickly bright yellow around the brown vascular lines and pales out toward the center. Because the fungus has clogged the stem's internal water pipes, the green tissue above it is actively starving of water and chlorifying (turning yellow)."

On 7/21/2026 at 9:41 AM, sonoranfans said:

In arizona I can tell you drip irrigation with a timer is the difference between life and death for some young palms unless you dote on them. The dead center is now a very good media for fungus to grow and expand. Whether the center is dead from lack of water or from too much, dead material is not protected from pathogens by plant defense. Never water these palms from the overhead, just water the ground around them and this is particularly important when you have dead new growth. Green material is generally protected by the plant chemical defenses(terpenes and enzymes) unless its catching water or moisture in a hole, like the bud. The leaves going straw color is dead and that risks the dead growth will retain water to assist fungal growth and the bud is not protected from fungal attack under those conditions. I'd keep pulling on the dead newest growth and get the hydrogen peroxide 3% on the bud area every couple days. I also use daconil fungicide as a follow up 2-3 hrs after the peroxide. If that soil there tends to always be damp, it may also be enabling the fungal attack. If the soil is dry at 6-8" depth just water it consistently but for a longer period, 90 mins. If you don't have a timer consider it, as you will not be able to forget watering. It might be that site has unusual drainage, you should know with a drainage test nearby(3' away).

The first response you had DoomsDave said you have a fungal attack. I gave the treatment (peroxide, daconil) which works for almost all treatable fungal attacks which are commonly reported here on palmtalk. Looks like AI says Dave was right, I am not surprised as he has been growing palms out west for several decades. Fungal attacks almost always happen on dead or weakened tissue, not live healthy tissue which has strong chemical defense mechanisms that kill or inhibit fungal growth.

A simple Google AI tells you how the infection occurs which is generally common knowledge here.

Fungal attacks on Washingtonia filifera (California fan palm) are primarily caused by airborne spores, contaminated pruning tools, and environmental stress. Key triggers and common fungal pathogens include: [1, 2, 3]

Common Fungal Pathogens

• Diamond Scale (Phaeochoropsis neowashingtoniae): Forms distinct black, diamond-shaped fruiting bodies on leaves and petioles, weakening older fronds. [1, 2]

• Pink Rot / Bud Rot (Nalanthamala vermoeseni): Attacks stressed or wounded tissue, producing pinkish-orange spore masses on the trunk or bud. [1, 2]

• Petiole / Rachis Blight (Cocoicola californica): Causes reddish-brown streaks on leaf petioles, disrupting water movement. [1, 2]

• Calonectria Leaf Spot: Results in localized spotting and tissue decline on fronds. [1]

Core Causes and Transmission Factors

• Wounds and Over-Pruning: Pruning green fronds too closely or using unsterilized saws creates direct entry points for pathogens like Nalanthamala and Fusarium.

• Excess Moisture: High humidity, prolonged wet fronds, or poorly draining soils create ideal conditions for spore germination.

• Environmental Stress: Cold damage, nutrient imbalances, or planting in wet, non-desert conditions weaken the palm's natural defenses. [1, 2, 3, 4, 5, 6, 7]

SO yes environmental stress, prolonged wet leaves, poorly draining soils all can lead to spore germination. But the spores are always in the air, is your palm susceptible? Hopefully yuou have al;ready been applying the peroxide and Daconil. I do not know why your palm is susceptible to fungus, only you know the history of your palm, the environmental stress could include bad soil, nutrient deficiency, overwatering of the leaves in cool weather etc.

I don't know why it's susceptible either. It's been perfectly happy and healthy as has the rest of my yard. Everything has been vigorous and deep green.

Zero moisture overhead from Feb until our monsoon season started a week ago. Driest winter on record. Zero snowpack for our zone. These were behaving this way long before the moisture finally came.

They get regular drip irrigation as I've lined out before. Only thing I can figure is poor soil. But I've seen folks plants these in the worst places and they somehow thrive.

I spent several more hours challenging AI and uploading more pictures and other pictures of similar looking petioles, it says are perfectly normal. It contradicts itself.

Regardless, I've ordered 3666F systemic fungicide. I read its the best for all true fungal diseases. I pruned all 15 of my mature palms 4 days ago and may have used the same saw blade. I cannot afford to lose any of the others. The yard is totally finished at this point with limited access and many of these trees are 13 ft ground to heart. I plan to soil drench every last one.

Here are some examples of the happy palms.

Meanwhile, its these two on the drive to my shop that are struggling all the sudden.

I had one spot in my last yard where it seemed a dead zone for planting a smallish palm both the palm and its replacement died. When I dug to plant a big palm at the same site, I found construction debris, all kinds of stuff cauking acartridges etc,. I have spots in my yard now that don't drain particularly well along a designed drainage path. A few years back(4-5) we had 23 inches of rain in august, raining 22 days in a row and a 25 foot bismarck got sick and it was attacked by weevils, dead in less than a month. The phoenix rupicola next to it was fine with the soggy soil, didnt miss a beat. Different species will often have different susceptibilities. The fungus spores are all around your yard, they have impacted just a few palms at most. A soil chemistry/composition test might tell you something, but I would also take a sample or two from near healthy washies to compare. If I was going to take a test I would dig down at least one foot for the soil, dont take surface soil.