Color Catcher is invaluable and it works. You buy them in any grocery store or good old wally world. They are with the rest of the laundry supplies. The ones I have are made by Johnson & are Shout. I don't know if anyone else makes them now.
They look like a dryer sheet and you throw it in when you wash your fabric and you can wash red with white and the color goes into this square instead of into the other fabrics. Don't ask me how but I can tell you it works.
I am a firm believer in prewashing everything because I have a pink quilt that used to be reds & white. What you are working with is a little harder because of the strips but whenever you wash it I would use the color catcher.