Sago Palm Help!!

[AlanS]

Anyone out there had similar issues!? I have two advanced sago palms (not a real palm) planted in the front yard. One has taken a sudden turn and now the second is following. 
 

it starts with brown spotting on the leaf before gradually turning yellow. I’ve sprayed an oil 3 weeks ago and just recently a manganese spray. Can’t help think it’s a bug that’s into it, or fungicide. I’ve checked the soil and it’s not waterlogged. 
 

 

[Merlyn]

@AlanSgenerally you'll get more replies in the "Tropical looking plants - other than palms" section of the forum. 

• It hasn't been cold enough in Melbourne for it to be cold damage, so I'd rule that out. 
• Initially I thought it was hail damage causing those small brown dots on the leaves, but if it's progressing from nothing-to-dots-to-dead then it probably was not hail.  I had a big hailstorm here over the summer and my 6 big trunking sagos all have small yellow dots on the leaflets.
• Check the underside of the fronds and leaflets for small white insects.  This could be CAS (Cycas Aulacaspis Scale) though I don't see any signs on the top of the fronds.  Usually it infests the underside of the leaflets first.  If there is scale it can be treated and cured, I've done it on all of mine.  Neem oil honestly is useless against CAS.  I take a hose and spray off the adults with a regular high pressure hose-end-sprayer, do a soil drench with Dinotefuran, and then spray the whole plant (including the growing point) with Acephate or Malathion.  But don't do this unless you confirm there's actually CAS on the plants.
• If you sprayed Neem oil (or any horticultural oil) around mid-day on a sunny or hot day...that'll burn the sago leaves.  I did this to one that had a scale infestation and all the fronds started dying off in a few days.  The oil beads up on the leaves and acts like a bunch of tiny magnifying glasses, burning the leaves.  It's why they say to spray in the evening, as the oil will dry to a film overnight and not burn leaves.
• It might be a root issue, if the plant is sitting in a damp area.  I have one in my "tropical bed" that gets drenched with fan sprayers every morning, and it's ~35 years old.  So they can tolerate lots of water as long as it drains well.
• My best guess though, is the plant is "eating" the old leaves to grow a new flush.  If you look at the center/crown there's those tall brown stabby spikes.  There's a gap in between in the center, that's usually a sign the sago is preparing a flush.  One way to check is to take a photo looking down in the center on subsequent days.  If the little stabby bits are moving around from day to day then it's growing new leaves in the center.  The yellow areas towards the center rachis/petiole look like a combo nutrient deficiency, probably a mix of nitrogen, potassium and magnesium.  I'd give it a good handful of any "palm special" type fertilizer, plus a handful of magnesium sulfate and manganese sulfate.  That should help it if it is "eating" the old fronds for nutrients.

[96720]

@Merlyn where do you find tropical plants other than palms 

[Merlyn]

@96720if you hit the "home" in the bottom left it'll show you the other forums other than the "Palmtalk" like "Off-topic" and the "Tahina" forum.  I'm not sure why they chose to separate things out, but they did!

https://www.palmtalk.org/forum/forum/4-tropical-looking-plants-other-than-palms/

[96720]

Thank you @Merlyni have sick cycads that I need help with and know this is not the place!!

[AlanS]

@Merlyn thanks a lot!! You’re a wealth of knowledge  

Since the manganese spray, the leaves have actually greened up a little this morning. So hopefully just a nutrient deficiency. I’ll give the palm fert a go and see what happens from there.

Are you from Melbourne too? Love to pick your brain on tropical plants for a Melbourne garden! 
 

Thanks again!! 

[Steve Mac]

Definitely manganese deficiency, don't be sparing with it. Mine used to do that too.

[Merlyn]

I was told that manganese is not "mobile" within plant tissue, the official term I think is "Translocation."  This means that the plant can't steal manganese from old fronds to deliver it to another frond or to new growth.  So while Manganese deficiency is likely, it probably can't be the reason why the fronds are yellowing and dying.  Manganese deficiencies show up in new fronds, but never in old ones.  If you look at the 4th and 5th photos here of "frizzle top" you'll see what I mean:  https://hort.ifas.ufl.edu/database/nutdef/report23_Mn-MG.shtml

That's why I suggested Magnesium as an additional supplement.  I think it probably will need both.  The Manganese foliar spray might help, I've never tried the stuff.  But I think the general purpose "palm special" with an extra handful of Manganese Sulfate and Magnesium sulfate is most likely the key to getting a good spring flush.  It's always possible there's some root or crown rot going on, you could try gently pushing the plantor it might not like the basic soil in Melbourne.  Some nutrients just don't get absorbed well if the soil isn't slightly acidic: