Bismarck fronds browning Sooty mold?

[RandiH]

I have a Bismark with browning on the tips of outside fronds and working its way up the frond center.  My Ag Agent suspects sooty mold and I am able to remove some of the "black" which reveals a brownish green below.  I haven't seen scale but I'm willing to spray Neem.  Any suggestions as to the cause it's greatly appreciated. The final photo is a frond that was sprayed with water on "jet" hose nozzle to remove "the mold". It is lighter in color - but scale I can't find. The cinnamon colored fuzz on the emerging fronds are perfect so I'm at a loss.  

[TampaBayRay]

I would cut that frond off at base n dispose that before something if anything spreads

 

[Merlyn]

I have seen that on Bismarckia when not in full sun, or on mine as latent wind damage from the 2 hurricanes last year.  I suppose it could also be a lack of water or maybe Potassium or Magnesium deficiency?  Sometimes the fungus is a byproduct of the real problem...maybe. 

[Billeb]

I had a really bad case of black sooty mold last year on quite a few plants. Howea, Licuala & Baronii. When I saw it on my favorite Hedyscepe, I decided to take some action. I sprayed multiple applications and what seemed like gallons of a Malathion mixture on anything and everything. After about a month, it was gone and couldn’t find evidence of it anywhere.  
 

It’s a bit difficult to determine if it is indeed sooty mold on your Bismarckia but if it is….it will probably be on most of the fronds. Some heavily covered, some mildly. I think cleaning with a pressure washer is more of a temporary rectification where a product like Neem or Malathion remediates for good. 
 

Good luck. 

-dale 

[PalmatierMeg]

Were you slammed by hurricanes last year? Ian really did a number on Bizzies.