roto rooter snaked my drain next to the washer tub and said he had never seen tree roots in that type of drain before. since that end of the house is the only side having a problem...the toilets are at the other end of the ranch house and worked fine... i dont think putting this product down my toilet will get to the roots i am after. should i use a different product? the plumber just said to put some root killer down the drain. thanks for any help.

Do not attempt to put the foaming root killer down anything smaller than a 3" line! What type of drain was 'next to the washer tub'? It may have been hair and not roots, or strings from laundry. If you are getting roots inside a branch line under the house, root killer won't do any good anyhow. If this drain is under the floor, it is going to need to be dug up and replaced at some point, and a video inspection will tell you what is really going on, how severe, and where exactly the problem is located. More information would be helpful.

"Roots" at that end of the system would mean that either they have filled the whole system, or there is a break in that line where they are getting in. OR, it could mean his diagnosis is incorrect. Only a camera inspection can tell you which of the three is the real cause.