Question
I have three Foxtail Palms that my yard man tells me have fungus.  It's black in color but there are no droppings or deformities.  The leaves are turning brown but the are still growing like weeds.  I was told to mix laundry detergent with water and spray them.  Is this correct?  I've been doing this for about two weeks but I can't tell if they are getting better or worse.

Answer
The black fungus is probably sooty mold which is just growing on the surface of the plant and is not parasitic.  It is there because there is probably an insect problem, such as scale or aphids.  The leaves may also be sticky with a sugary substance called honey-dew that is secreted as the bugs feed.  Then the black mold grows on the sugar on the leaf surface.  The control is to control the bugs.  I would buy Bayer Advanced Tree and Shrub Insecticide from Home Depot and mix with water and pour around the base of the plant on the soil.  It is taken up systemically and will kill the bugs in a week or so.  Look for small brown, oval shaped bumps on the fronds or undersides of the leaves.  If you see these and you can scrape them off with your fingernail, then it is scale insects.  The Bayer product will fix this.  The sooty mold will then go away on its own or you can use the soap and water to rinse some of it off.  I hope this helps.