This really works, and it is non-toxic! Mix equal parts of Listerine (or 
store brand, but ONLY the yellow color ones), dishwashing LIQUID (any 
kind, any color), and water.  Pour into a spray bottle or hose-powered 
feeder and wash down the affected areas.  It doesn't seem to harm plants 
or grass, either.  I use it frequently having 5 dogs! I spray it on the 
fence, on the outside walls of the house, patio, even the wood decks 
without having any discoloration or other problems.  Test in a small area 
if you have concerns, but I LOVE this concoction!

Just found this. Interesting! I'll give this a try and get back. Thanks.