Bt for omnivorous leafroller on grapes?

After a quick image search I believe we have a pretty solid infestation of omnivorous leafroller among a few vines being trained for an arbor.

Growth is really just getting going, but it am finding a single small larva in over 50% of the tips. I need to gently open up the unfolding leaves to get to them, and they seem to add a bit of webbing to the naturally tight budding cluster.
Body beige,head dark.
The problem was small because of the planting size and age. I could just go through and check the vines, smooshing as needed. Manageable but tedious.
I know they are susceptible to Bt, but I would think timing critical as I just don’t see any spray getting down where they are feeding.

It’s a new pest to me. Any advice on organic control measures?

Check out the UC page on leafrollers, I think all your questions are answered there.

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7473.html

It sounds like they are usually not worth spraying due to the limited damage, but Bt will work on them.

Scott