Pressure wash versus another method
Do you know of a method to rid sidewalks of moss? Would a treatment of Roundup be effective? Thanks.
Lane County Oregon
Thanks for your question about moss control. As a general rule, the physical removal of a pest (basically anything that is someplace you don't want it!) is superior to chemical controls. (And, of course, cultural control--making sure it isn't there in the first place--is even better). So, pressure washing will clear the sidewalk (or roof or driveway) and, interestingly, also provide nutrients to the plants that it is blown on (as the moss breaks down and feeds the soil.) The use of Roundup is dangerous, because it will also kill anything else it lands on.
Here is an answer our Extension agent gave to a similar question about 4 years ago:
"Moss control in a driveway is best removed physically per the instructions at the following web site. http://bryophytes.science.oregonstate.edu/page18.htm Chemical control will also work, but the moss will likely grow back faster than through physical removal. See the link above for details.
Regardless of how you control moss, it will likely grow back if you do not change conditions (shade and moisture) that are conducive to moss growth. Consider pruning overhead trees to let in more light if that is a possibility at your property."
In other words, moss, like most other plants, will grow where conditions are best, and often 'take over' lawns because of the shade and moisture. Hope this is helpful. Good luck!