|Prometon is the active ingredient in 'Total Kill' and it is a vegetation killer, especially targeting broadleaf weeds and plants. It isn't as effective on grasses (as you've discovered). The damage you see on your trees and other broadleaf plants may be only temporary but may show up for quite some time because the chemical was taken up by the roots of the plants and will be throughout the vascular system. I don't know whether the damage will be permanent, nor can I say how long it will take for the chemical to degrade. I can only suggest that you contact your local cooperative extension office for professional advice. (I'd list the address and phone number but you didn't indicate your city or state on your question.) Look in the phone book under county listings for cooperative extension, or contact your state university for a list of their county agents. Someone there can direct you to some experts in the pesticide field.
Best wishes with your landscape. - just as a side note, there are both specific and non-specific herbicides on the market. Total Kill is non-specific, meaning it will kill anything it touches. If you want to kill grasses in a flower bed, choose a grass-killer, not a vegetation killer. Likewise for your lawn - use a broadleaf weed killer to get rid of dandilions because it won't harm the grass.