Help with Mediterranean Palms Once Healthy but now yellowing June 2024

[SunnySide]

Hello everyone, I am new to this site, so please bear with me as I learn how to navigate. I have several Mediterranean Palms in my yard, and all do very well, but these 2 particular ones started to yellow on me this year.  I give names to all my trees, and these 2 are named: Cowboy and Pachuko.  I can't figure it out. I watered them only once in May 2024.  Then today 6-17-24 with some Manganese. Med Palms are usually bullet proof, Cowboy has never really grown much since planted in 2018, and over the past couple years his rachises were always just a whisker yellow, the lower fronds, the oldest fronds always seemed to have yellowish rachises. But now All the fronds on his main center stalk are all yellow with yellow rachises. He just never seemed happy. Pachuko has grown a lot since planted in 2018, never given me issues, but this year all of a sudden giving me yellow fronds, but rachises are green.  Again, watered only once in May 2024, then today 6-17 with just a cup of Manganese. See photos attached. If anyone would like to see more photos, or better photos, just let me know. Can you please share your expertise? Nutrient deficiency? Over watering and wet feet? Location of palms: Scottsdale, AZ. Thanking everyone in advance for their input.

[Merlyn]

@SunnySide I am not sure about watering in AZ, but Chamaerops can take a lot of water here in sandy FL.  They probably want less water in clay soil, but at least some water when it is so hot.  Hopefully some locals can chime in.

For the yellowing, that is typical of a Magnesium deficiency, not Manganese.  Magnesium gets stolen from older leaves to help grow new ones.  It always shows up as yellowing on the oldest fronds.  Manganese is not "mobile" within plant tissue, so the plant can't pull it out of old fronds.  Thus Manganese shows up as yellowing on new leaves only.  

The standard fertilizer recommendation for FL soils is something like PalmGain 8-2-12.  That's because FL soils are really high in Phosphorus and don't need any extra.  6-17-24 sounds like an odd ratio., I have never heard of one like that.  I would get something in the 6-1-8, or 8-2-12, or something like that palm specific.  Add a handful of Magnesium Sulfate to each palm.  It may take a while to fix the deficiency, but it should slow down the yellowing.

Don't cut off the old fronds until they are completely dead, at least for now.  If you cut it off then the palm will just steal Magnesium from newer fronds faster.

[SunnySide]

8 hours ago, Merlyn said:

@SunnySide I am not sure about watering in AZ, but Chamaerops can take a lot of water here in sandy FL.  They probably want less water in clay soil, but at least some water when it is so hot.  Hopefully some locals can chime in.

For the yellowing, that is typical of a Magnesium deficiency, not Manganese.  Magnesium gets stolen from older leaves to help grow new ones.  It always shows up as yellowing on the oldest fronds.  Manganese is not "mobile" within plant tissue, so the plant can't pull it out of old fronds.  Thus Manganese shows up as yellowing on new leaves only.  

The standard fertilizer recommendation for FL soils is something like PalmGain 8-2-12.  That's because FL soils are really high in Phosphorus and don't need any extra.  6-17-24 sounds like an odd ratio., I have never heard of one like that.  I would get something in the 6-1-8, or 8-2-12, or something like that palm specific.  Add a handful of Magnesium Sulfate to each palm.  It may take a while to fix the deficiency, but it should slow down the yellowing.

Don't cut off the old fronds until they are completely dead, at least for now.  If you cut it off then the palm will just steal Magnesium from newer fronds faster.

Thank you Merlyn, you've already taught me a great deal. I had no idea Manganese was not mobile. I will look into PalmGain. See attached image of this stuff I heard about from SouthernAG called Essential Minor Elements. Your thoughts on that, ever used it?

SCIENCE QUESTION: How does Magnesium Sulfate, which is Epsom Salt, give nutrients to a Palm Tree, yet when I make a mixture of gallon of vinegar, cup epsom salt, and half cup dawn dish soap, and spray my weeds, the weeds are dead within 8-24 hours, especially if it's hot? I'm always so afraid to put a handful of Magnesium Sulfate (aka Epsom Salt) on my palms because of that.

On another subject, I have these 3 other tall Palm Trees, that I just can't figure out, can't figure out how to make them happy. I'm going to put together photos and details and do a post. I've had so many arborists try to give me advice--from CA to AZ to FL--and I've not yet found a tree doctor that can help them. Maybe you can take a look at the pics/post once up ... I'll have it up in a few days.  THANK YOU AGAIN for your expertise.

[PalmatierMeg]

9 hours ago, SunnySide said:

Thank you Merlyn, you've already taught me a great deal. I had no idea Manganese was not mobile. I will look into PalmGain. See attached image of this stuff I heard about from SouthernAG called Essential Minor Elements. Your thoughts on that, ever used it?

SCIENCE QUESTION: How does Magnesium Sulfate, which is Epsom Salt, give nutrients to a Palm Tree, yet when I make a mixture of gallon of vinegar, cup epsom salt, and half cup dawn dish soap, and spray my weeds, the weeds are dead within 8-24 hours, especially if it's hot? I'm always so afraid to put a handful of Magnesium Sulfate (aka Epsom Salt) on my palms because of that.

On another subject, I have these 3 other tall Palm Trees, that I just can't figure out, can't figure out how to make them happy. I'm going to put together photos and details and do a post. I've had so many arborists try to give me advice--from CA to AZ to FL--and I've not yet found a tree doctor that can help them. Maybe you can take a look at the pics/post once up ... I'll have it up in a few days.  THANK YOU AGAIN for your expertise.

Southern Ag Essential Minor Elements in granular form is great. Prior to Hurricane Ian I used it when I fertilized palms and I hope to do so again when I get the yard back together. My SWFL dreck calcareous soil is nutrient deficient, except for phosphorous.

[SunnySide]

29 minutes ago, PalmatierMeg said:

Southern Ag Essential Minor Elements in granular form is great. Prior to Hurricane Ian I used it when I fertilized palms and I hope to do so again when I get the yard back together. My SWFL dreck calcareous soil is nutrient deficient, except for phosphorous.

Good to know, thanks for feedback Meg.

[Merlyn]

@SunnySide I've used a couple of fertilizers from SouthernAg, but not the minor elements.  But it's got a good mix ratio of all the stuff most palms (and cycads) need to grow well.  I typically use a single-component adder like Magnesium Sulfate or Manganese Sulfate, and dose as needed.  But that's just because I use a "palm special" type fertilizer that already has the same stuff as the Southern Ag Minor Elements fertilizer, and I'm just supplementing one specific thing.  You could use either the Minor Elements or a handful of Magnesium Sulfate, whichever is easier to get and/or use.

As far as the weed killer with Vinegar, Epsom Salts, and Dawn goes, I have never used that.  I tried some vinegar-and-dawn weed killers, and they did kill off the top growth fast but the weeds just kept growing back from the roots.  Epsom salts are never an actual weed killer, so no clue why it would be included in a "recipe" like that.  I do use a couple of drops of Dawn in a 1 gallon sprayer of Glyphosate, as the soap breaks down the surface oils/protection on weed leaves and allows the Glyphosate to soak into the plant tissue better.  A quick search found this description:

https://www.southernliving.com/garden/weeds/vinegar-epsom-salt-weed-killer