Any company who applies any kind of anything that does a function – deters moss, kills moss, prevents moss, causes moss to fall off the roof, etc. needs to have the Department of Agriculture license and may only use registered EPA products where the label does what the company states that they are doing. Its a weird law, but it is Oregon law and I can see why it is in place, for the masses. Please ask us about our DOA numbers and legalities I can easily send them to you in an email. Also, please ask all companies who you are interested in, to see their DOA numbers for the treatment. Most companies do not have them, and they will tell you that it is not required, but that is not true. Nice to work with honest people and honest companies right? I think so, lets have a great, healthy, honest relationship! Those are always the best ones.