If it is actually wisteria seeds that are sprouting, then yes, the Preen should help to keep things under control. However, most wisteria sprouts are coming from underground roots - not seeds - in which case, the Preen will have minimal effect.

Would you be able to deadhead most of the flowers after bloom?

I've never deadheaded the flowers - it's not really possible in the mass of foliage. BUT once the foliage drops off in the late fall, the seed pods are very visible. I remove them all and discard them in the garbage (do not drop them to the ground and leave them there!). I've never had a problem with seedlings. (The first year our Chnese wisteria bloomed, I left a couple of pods up for the winter and then harvested them in early March, collected the seeds and tried to germinate them - to see if the seeds remained viable after our winter. I got a fairly high germination rate, so I've been diligent ever since about removing the seed pods in the fall.)

Thanks all, but my vines go 100' up into the trees and the bottoms of the vines are big around as my waist! They are probably 100 years old. Yes I get runners too, but its the seeds that sprout far and wide, including in the brick patio. If I don't yank them out when tiny they get roots to china! I will try Preen this fall...and spring.