The Mystery of the Browning Date Palms

13 June 2014 Idea of the Day “A great step to knowledge is to become conscious that you are ignorant of the facts.” Benjamin Disraeli, British statesman and prime minister

If you’ve been following the stories here you know I have just recently gotten a positive confirmation that a serious disease of date palms has been recently confirmed in the Tampa Bay area again in several locations – Texas Phoenix Palm Decline, TPPD for short. Unless caught early and treated with the right anti-biotic in the right way, it quickly kills the palm. And it not only attacks date palms but also the state tree – the sabal palmetto! It makes arborists nervous of what could happen to a lot of the palms that visitors expect to decorate the Florida landscape.

A few days ago I got a call from a close colleague who mostly deals in hardwoods. He doesn’t particularly like dealing with palms because a) they aren’t really trees and b) they are terrifically labor and time consuming without much pay for the trimming work. But now he had a problem. One of his largest customers had a palm problem and they were expecting him to fix it and save their investment!

“They have eight new Sylvester dates or maybe they’re Medjool dates, they look very similar when young, that they planted last December. Each one is about a $5000 investment so this is important. They were doing fine through the winter and the spring but now the lower fronds are rapidly turning brown in a much greater proportion than you’d normally see. Just to get a second opinion, would you go look at them and tell me what you think? Tell me if you think it could be TPPD since you’ve been examining a few of those cases recently.”

I said sure I’d be glad to look at them as the location was close. I drove downtown, parked right next to the area, got out and looked. This is what I saw.
Sylvester palms going brown
They were fairly attractive 15 ft. probably Sylvester dates. They had obviously been transplanted as mature palms, not grown from seedlings. Yes the lower fronds were not yellowing like you see with a nutritional problem. They were going from green straight to brown. And it had all happened in about the last three or four weeks.

I looked at all eight of the date palms around the edges of the little city park. Seven of them had dead flower stalks, so they weren’t going to flower or fruit this year. This early die off of the flowers and fruit is a typical sign of TPPD. But one of the palms still had bright orange flower stems with little dates at the ends.

Was this attacking the entire neighborhood? I walked around for about four square blocks and saw lots of other Medjool date and Sylvester date palms. The Medjools had bright orange flower stalks and were flush with dates. In fact, as I was walking along the sidewalk I’d occasionally hear them falling and one almost hit me in the head! The splattered residues of many dates were painting the sidewalks. Wow, outside of a farm these could really be a mess. I saw about fifty of these healthy Medjool date palms, so they weren’t been affected if this was TPPD.

When I found other Sylvesters in other parts of the neighborhood I noticed they did not have any orange flower stalks, only a few shells of dead ones. Hmm, could they all be possibly infected too? But they didn’t have brown fronds. They looked deep green and healthy. I saw a maintenance guy on his knees in a garden working on the landscape and thought I’d quiz him.

“Excuse me, sir, I’m an arborist doing an examination of some palms on a nearby property and I have a question.”
“Sure, what can I do for you?” he said, looking up with a big smile.
“I notice the orange flower stalks of all these Sylvesters are gone. This can be a sign of a disease. Have you seen any of the orange stalks this year?”
He had a ready answer.
“Oh yeah, we just went through last week and pruned them all out because we don’t want fruit falling all over the sidewalks this summer like they are on the other sidewalks in town!”
I laughed. I knew what he was talking about. This was encouraging.
“Oh good, glad to hear that. They’re not sick. I didn’t think so. They all look so green and luxuriant.”
“Thanks!” he said and went back to working on the garden.

So as I sauntered back to the problem palms around the little park area, I summed up some conclusions. This problem wasn’t affecting any other palm in the entire area. It made it seem more likely it was a problem just of these palms because leafhopping insects will spread TPPD.

I looked at the irrigation system and it looked inadequate. Palms don’t need as much water as hardwoods but they still need a lot when transplanted. These palms were just being fed by a drip system, almost surely not enough water.

I thought I would call a fellow arborist friend down in Sarasota who specialized in palms. As soon as you go south of the Tampa Bay area the climate changes to a more tropical climate and there are a lot more palms. He sees so many cases of everything for palms I thought he’d have some experience to draw on.

“Hey Wayne how are you? It’s Bob.”
“Hey good to hear from you!”
“Sorry to bother you again but I’ve got another palm problem.”
Wayne was always helpful.
“Well give me the facts. I’ll see if I can shed some light on it.”
I relayed all the observations and facts I had seen along with my worry about possible TPPD.
“Bob it doesn’t sound like TPPD. For one thing, I’ve never seen TPPD hit every palm, one right next to another like you’re describing. The insects roam and hop maybe the fourth one down, then the third one after that and randomly after that.”
“Oh that’s interesting,” I said, “and good to hear too!”
“Yeah, plus these browning symptoms are only affecting the newly planted ones. So I think you’re safe in that regard. I suspect this is transplant shock made visible by the recent last month of new summer heat and an insufficient water supply. They should install bubblers instead of a drip system.” He continued. “When palm roots are cut at transplant, it’s not only a shock, but unlike hardwoods their roots don’t continue to grow from the cut. They have to start new growth from the base of the trunk. So they do need a good amount of water to establish new roots. Heat will cause a much greater pull of water loss out of the leaves. Not enough water in the palm will brown the fronds.”
“That’s sort of what I was starting to think,” I said. But I wanted to pick his brain a little further. “You’ve cared for thousands of palms. What would you do next if this was your problem?”
“Well of course I’d get the irrigation system to deliver more water with bubblers, but I’d also give them a little fertilizer nutrition to help them come back. I wouldn’t use granular amendments which can be slow to get to the palm because of the new slow release coatings. They need help right away. I have found and used a liquid palm fertilizer which I’d apply at only a light dose of a pound per palm now and then again in six weeks. That should help a lot.”
“Well I hope you’re right! Otherwise this could be an expensive loss for the client and a black mark for my colleague in not being able to save them,” I concluded.
“I think you’ll find this will do the trick,” he responded.
“Thanks again, really appreciate your sharing your expert experience!”
“Sure, any time.”

I relayed all this to my colleague. I hope he’ll do it. We’ll see in a week or two if its going to be the right answer to save these valuable palms.

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6 comments

  1. Help!

    I think my Sylvester (5 stem, planted in Feb) might have TPPD.
    Leaves turning brown-red with not much yellow before the brown.
    Lots of brown (about 20-25% of the canopy) and very recent.
    Thought it was the heat and maybe lack of water.
    But now I see the inner leaves that have just unfurled also have a tan sheath. Is that normal?
    Is TPPD incurable or can I control it with natural remedies and better care?
    I’m in north Saint Pete in the region of US 19 and 9th Avenue. Is the disease prominent there?

    1. Hi John,
      Yes the Phoenix Sylvestris is a susceptible Phoenix date palm and yes you live in an area that has definitely been exposed to TPPD in the last two years.

      But no, sylvester dates are not 5-stem. You likely have a Phoenix Reclinata, also susceptible to TPPD. Send a photo. But yes with that much brown and the new growth leaves at the bud (called the spear leaf) already brown, it’s a distinct possibility. If the new spear leaves all come out brown it’s assured your palm is dead – the remaining fronds can even stay green for a while after the palm is technically dead – not producing new growth. I’m not sure what you have, so send a photo.

      Another sure sign is the color of the seed strand if you have a female palm. If you do, the strand should have been orange through summer, possibly going light wheat-colored this time of year with green dates that have changed to dark purple. But if these strands are darker brown and the fruit is brown, it is another sign your palm is on its way out.

      Like I say in my blog, the only way to know for sure if it is TPPD is to have someone like myself do a core drill extraction and send off the sample to a state lab for testing, the cost is $250. The reason this could be important is that if it is TPPD, all other homeowners in the area might want to save their expensive date palms by injecting them with the Oxytetracycline anti-biotic before they catch it from the leafhopper insects that spread it. This is the only known preventive. But it has to be maintained with injections three times a year to maintain the protection. So it’s not an inexpensive proposition to save your palms. It’s really only economical for the big expensive date palms like the Medjools and Canary Island date palms. Once the palm has TPPD, there is no cure. And a palm can look fine for a few weeks even after infected.

      Good watering and fertilization always make trees and palms immune systems stronger and less likely to catch fungal and other diseases, but are not a guarantee against infection especially with a strain as virulent as TPPD. Sorry I couldn’t give you better news. This disease is attacking all of Pinellas and Hillsborough County now and not only threatens at least four varieties of date palms but also our state tree, the Sabal Palmetto (cabbage palm), whose loss would majorly change our semi-Tropical landscape. In addition Clearwater and Largo have both lined their major thoroughfares with large, expensive Phoenix dactylifera Medjool date palms which are susceptible.

  2. I live in Wimauma, and we put our Sylvester Palm in back in June 2014. It’s looked beautitul until this past August. We had someone from Mainscape (they do all our landscaping in our community) come over and look at the Palm. He said it just needed to be trimmed. My husband trimmed it, and 2 weeks later here, the leaves are all brown again. There must be something more going on with the Palm – HELP??!!! How do I check for TPPD??? Other Sylvester Palms in our community look great, but ours really looks bad! HELP!

    1. Hi Tina,
      Yes it could be TPPD. What percentage of its fronds are brown? Is the vertical spear leaf (the one that shoots up from the top center of the head) green or brown or non-existent?
      These will be indicators. The rainy season of August is when it spreads the best in the humidity. But the only way to know for sure is to take core samples per directions provided by the University of Florida plant pathology lab and send to them for DNA testing. Cost for us to do is $250 but we don’t go out to Wimauma. See below for the importance of removing it if confirmed and letting out neighbors know so they can inject the anti-biotic on a schedule if they want to be super pro-active in saving any of their valuable large date palms.

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