Here are a couple of suggestions, Jon:
Zink strips. to prevent redevelopment. As far as removal, this will depend upon the current condition of the roof itself. If the roof is real old most likely you will end up needing replacement. If not a spray of bleach being careful not to get any on your shrubs then using a driveway power washing broom with long handle power wash the roof to remove the offending moss. Ideally this should be done by a professional that does roof cleaning. But If you really have a lot of moss development, most likely you will need to replace the roof as the moss has developed roots into the lamina below the gravel surface of the shingles which destroys the shingle from behind. Black stains can be removed using black alge chemicals found in pool supply. You need to spray the diluted chemical onto the roof using a garden sprayer. Again being careful not to get any on shrubs or grass. Let it dry and then rinse off with hose. It may take a few cleanings to remove this stain, but it will lighten after each cleaning.
Thanks for the info! The roof is dimensional asphalt shingles,& its not that old...probably 10-11 years.I dont want to,& cant afford to replace it rite now.Ive heard of the zinc strips,but Ill be needing someone else to put those on. I'm 6' 3" think I should keep my weight off the roof,as its a good pitch & I dont want to damage it.I was hoping I could just spray something from the ground to kill it,but I guess zinc or copper attached would do that anyway.Then wash it off after,I guess.
The very first thing you must do is remove the reason for the moss. Typical reasons are trees growing over the roof not allowing enough sunlight to hit roof. Then cleaning, brushing etc will remove. Then Zink strips placed along the top course of the roof will help prevent another outbreak of the growth.