Washingtonia diamond scale?

[Raffinator]

Hi palm experts,

Was seeking some help identifying a condition that I suspect my Washingtonias suffer from. I live in San Francisco, very close to the ocean, I'd say about 1/2 mile or less from the coast. We get lots of marine moisture in my neighborhood. I have two Washingtonias in my backyard, southern facing, in very fast draining sandy soil. They've been in the ground for about 15 months or so, not sure if they are established yet. I purchased them from Lowe's as 15 gallon container plants, where they were labeled "Washingtonia Robusta", but I believe they are more of a hybrid, probably a "Filibusta", as the petioles are very green and show little hint of that tawny red color that is associated with the true Robusta, and the fronds have those distinctive filifera fibers that you see in the California fan palms. This leads me to believe they might be more susceptible to moisture problems. They've been growing fine, but I've noticed that all but the newest fronds suffer from a premature yellowing, with black spots that seem to be similar to the diamond scale fungus that apparently affects these palms. I wasn't sure if this was the case, or maybe I was just being paranoid, so I was seeking some opinions on this from fellow palm enthusiasts. I've included some pictures of the affected plants.

I'd like to know if you agree that these Washingtonias are suffering from diamond scale or perhaps some other issue, and, if so, is there a treatment for this or perhaps a course of action you could recommend that I follow to alleviate the problem? (Fewer waterings, different fertilizers, palm spikes, etc). Thanks in advance. This is a great forum!

[Patrick]

Raffinator- welcome!

Well, what you pictured is definitely not diamond scale. You're being a little overly cautious. Don't worry! You have some tough little palms there.

Just a little wear and tear on those leaves. Your palm will grow out of it. They look like they could use a little fertilizer- but once it warms up, of course. Oh wait, I forgot about your location- when it stops raining so much.

They'll be fine.

Did you recently plant them?

Ok,again- welcome to the forum!

Next on your list should be a Ceroxylon

Edit: you haven't recently fertilized them have you? It almost looks like in the first picture that your palm has a slight potassium/magnesium deficiency.... of course someone is always welcome to correct me.

[Raffinator]

Raffinator- welcome!

Well, what you pictured is definitely not diamond scale. You're being a little overly cautious. Don't worry! You have some tough little palms there.

Just a little wear and tear on those leaves. Your palm will grow out of it. They look like they could use a little fertilizer- but once it warms up, of course. Oh wait, I forgot about your location- when it stops raining so much.

They'll be fine.

Did you recently plant them?

Ok,again- welcome to the forum!

Next on your list should be a Ceroxylon

Edit: you haven't recently fertilized them have you? It almost looks like in the first picture that your palm has a slight potassium/magnesium deficiency.... of course someone is always welcome to correct me.

Thanks for the warm welcome, Patrick!

OK, good to know that you don't think there is a diamond scale problem. I'm new to palms and fairly new to gardening in general, so maybe I've jumped the gun a bit. Just trying to be good to my palms, I guess. Yes, these were planted in November 2010, about 15 months ago. Don't know if that's a lot of time or a little. We had a very wet winter in 2010, very dry winter so far in 2011. In terms of fertilizer, I use EB Stone's hibiscus fertilizer, just spread it around the drip line of the palm trees in the spring and the summer. Also use a little fir mulch.

You mentioned maybe a potassium/manganese deficiency... I have no idea if that's the case, due to my ignorance, but I do know that my soil is basically pure sand (this area was a giant sand dune before it was developed many years ago), so I doubt that it has much nutrients. I've looked into using palm spikes, but not sure if its necessary. Thanks again for your response. Looking forward to adding more palms to my repertoire!

[Tom in Tucson]

Welcome to PalmTalk!

I agree that you have hybrid palms with at least some filifera blood. My pure filifera (from seed collected in native palm groves in the desert) spot up considerably in the cooler months. The new leaves which grow after the weather warms should look normal, but those spotted leaves will continue to look worse (getting gray with mildew spots) as they age. Try growing more cool tolerant palms (Parajubaea, Ceroxylon, etc.) in your climate. If you need faster growing species try something like Archontophoenix.

High 66F, Low 46F

[Jubaea]

You may want to consider getting a fertilizer that is specific to palms. Many fertilizers don't have any magnesium in them and with sandy soils it does not take much for the nutrients to leach down away from the root zone after heavy rains or deep irrigation. I prefer to use granular fertilizer as it does not concentrate all of it in one area.

[Darold Petty]

Welcome, Raffinator! We need to talk, as I live at 33rd & Vicente.

Your palms do have potassium deficiency, and I can give you some palm-specific fertilizer. You should visit my garden also. I will send you a PM (private message) with contact information.

[Patrick]

Listen to Darold- he's da man! His garden is a fine representation of what can be accomplished in your neck of the woods.

Yeah, I'm feelin' ya on the sand thing. Where I live- about 1.5 hrs east from the sunset- this area is pure sand, too.

I've learned that having a bag of sul-po-mag fertilizer as well as the regular palm fertilizer is helpful. The big orange home store has acceptable palm fertilizer- a Washingtonia should do well with it.

Next on the list- just get a Kentia because I sure can't grow one where I am!

[Raffinator]

Thanks guys for all the responses, I do appreciate it. This place is awesome.

Darold, practically neighbors! I'm out by the cliff house, so we definitely share the same challenges. Thanks for the invite, I look forward to seeing your work. Can you recommend a palm specific fertilizer that would be best for the outer sunset/richmond?

Patrick, as a matter of fact I do have a Kentia palm. Its my one house plant. Several in one pot. Doing pretty well too. I'd like to put them outside once they outgrow my living room.

Potassium deficiency. Seeing as how poor the soil is, that makes sense. I agree that more moisture friendly palms are the way to go for my spot. Thank you for those recommendations.

[Patrick]

Challenges is a fine way to put it, but you do have some great benefits that make your climate very unique. I can't grow a Rhopalostylis out here to save my life! You, on the other hand have the perfect climate for it. You can definitely create a little slice of heaven out there.

Your Kentia would probably do better outside in the ground.

If I'm not mistaken, the Richmond/ Sunset area is somewhat similar to the Lord Howe islands and New Caldonea, which provide a great variety of flora for you to grow. I think you could probably get away with Trachycarpus martianus out there as well. I love that palm but it gets just too hot out here for me to grow it. Maybe not. Go see Darold.

[JasonD]

Hi Raffinator,

Darold will put you on the royal road to palm heaven.

My two cents, for fan palms that will thrive rather than languish in the Richmond District: Brahea edulis, Trachycarpus martianus, wagnerianus, & latisectus. You might also succeed with Pritchardia minor, if you've got a bit of protection and can irrigate. Washingtonias will never be very good-looking in our fog/wind belt. Only east of Arguello do they start to take on the proper appearance of a happy tree, and only in the Mission do they actually flower and set viable fruit.

For fertilizer, make sure the Nitrogen-Phosporus-Potassium (NPK) ratio resembles 3-1-3, and then add the equivalent of a "1" in Magnesium.

Come visit Flora Grubb Gardens in the Bayview and say hi.

Great to see another San Franciscan on Palmtalk.

Jason

[Raffinator]

I got a chance to take the grand tour of Darold's palm garden this past weekend. Nothing short of amazing! All kinds of species that I would never likely see unless I traveled the world. And Darold himself was really generous with his time and knowledge, which I really appreciated. It was like attending a seminar in palm education. I'll post a few pics when I get the chance.

Patrick, I plan to put my Kentias outside when they grow large enough, or maybe eventually pick up an older specimen (which are apparently cheap right now) so I don't have to wait so long. You're right, after visiting Darold's garden, its easy to see palms thriving where I live, so long as I pick the right ones for my climate.

Thank you for the knowledge, Jason. I've heard of Brahea Edulis. Nice palm. Putting that on my list, as well as the Chinese windmill palms, which seem to do well out here. The two others that you mentioned, Pritchardia minor and Trachycarpus martianus, I had to google, due to my ignorance, but they are right up my alley, aesthetically speaking. Are they available as plants locally, or are seeds the only way to get them? I've been to Flora Grubb gardens before. Beautiful place. Very inspiring.

Maybe the Washingtonias weren't the best choice for my climate, but their a favorite of mine. Apparently they don't mind being transported so if I ever move or find a better spot for them, hopefully I'll have that option.