Hi all. We planted four C. costaricanas about a year ago. They almost immediately became our fastest growing palms and we are very happy with the choice. But one of the stems has had a couple of "accordion leaves". From @Darold Petty's excellent link on another thread I gather that this can indicate a boron deficiency. I applied liquid palm fertilizer with 0.02% boron, and followed up with Palmgain a couple of weeks later. Is there anything else I can or should do to address this? TIA.

@Foggy Paul the same UFL website has another boron page: https://edis.ifas.ufl.edu/publication/EP264

Near the bottom they say "Dissolve about 2–4 oz of Solubor® or Borax in 5 gallons of water and drench this into the soil under the canopy of a single palm."  I might do 0.5 to 1oz and see if it comes back in future fronds.  A bit of accordion leaf is fairly mild, and too much boron can be phytotoxic.

@Merlyn is right, I followed that protocol for a Neoveitchia that developed a slight Boron deficiency just as you pictured. One treatment and the new leaves are now back to normal. It took about 3 new leaves until the symptoms were completely resolved. 

Thanks all! Borax is on the shopping list 😀

Update: I applied the boron solution about two months ago and hope to see improvement in future leaves. But meanwhile, I have this distorted shoot and I can’t tell whether it’s related to the boron deficiency or not. Any ideas? Again, TIA for any suggestions. 

56 minutes ago, Foggy Paul said:

Update: I applied the boron solution about two months ago and hope to see improvement in future leaves. But meanwhile, I have this distorted shoot and I can’t tell whether it’s related to the boron deficiency or not. Any ideas? Again, TIA for any suggestions. 

One of my Chamaedorea seifrizii had a spear that looked exactly like that. It grew out of it and I didn't apply anything. I just watered it more often.

That looks more like a crown rot to me.  A squirt of hydrogen peroxide will confirm fungus.  If it bubbles it's fungus, if it doesn't bubble, then it's not!  I'd do H2O2 and then Daconil, repeat 2x or 3x per week until it stops bubbling up.

23 hours ago, Foggy Paul said:

Update: I applied the boron solution about two months ago and hope to see improvement in future leaves. But meanwhile, I have this distorted shoot and I can’t tell whether it’s related to the boron deficiency or not. Any ideas? Again, TIA for any suggestions. 

  It well may be the boron deficiency, the apex of the spear looks deformed. Please consider that the micronutrients deficiency affects the new leaf from the beginning of its development, so you now may be looking at the leaf that started to develop more than two months ago.

Also, if the pH of your soil is very low or very high, the uptake of boron through roots may be minimal