Green Magic is a contact spray. It works well, but its not a control product. It doesn't nothing to control the rust, it only kills the spores that it comes in contact with.
It wont harm your plants. I have used it multiple times this year with no ill effects. Its a Biodegradable degreaser. You would have to up the concentrate on the degreaser to non-suggested levels to harm your plants.
Simple green, or 1 TSp. dawn per gallon will in effect work the same way.
Again this will only kill the spores you can contact.
