11/15/2014
We know that some folks prefer to just spray on D/2 without either much before or after work. We don't feel that's the best approach and this photo shows why. We found some granite coping in a cemetery covered with lichen. We sprayed D/2, full strength, on a few, but did nothing else. You can see lichen untouched to the right as a control.
The D/2 did a quick job on the lichen, turning them brilliant colors within 2 hours and after 24 hours the lichen were clearly dead. But they were still there and quite attached to the granite. Also notice the discoloration extending from lichen about 1/8" in all directions.
Thus, the D/2 does a great job killing biologicals, but killing isn't the same as removing. It's supposed to rain in the next couple of days and we'll post again on how effective the rain was in removing the dead lichen and associated stain.