I'm sure you will get "more expert" advice, but I can tell you from personal experience, that unprotected plants will be at risk. I think even if you planted late, (like I attempted to do) they still got hit. I found something that my brother in law uses (he's a professional landscaper) and they have a HUGE garden full of squash etc. and NO SVB, NONE, just a row of about 60 + pretty squash plants producing liek crazy...Of course it's a high powered chemical but it works, period.

Acephate pro75

I picked some up from him and intend to use it on the squash I have left that have NOT been attacked by the SVB, maybe I'll get some to grow untouched!

Thanks rjinga:
Using an insecticide would be my last resort.
I probably will end up enlarging my row cover to accommodate the growing plant. Will have to find a way to pollinate the plant if I keep the covers on. Paul

OK, here are my results. I used a row cover till the plants started flowering and then took the row cover off permanently. The plants have really done well and are producing well. No svb damage so far. I am happy with my experiment.

The SVB has killed every single squash I've planted this year. For next year I plan on using row covers. As the plants start blooming with female flowers, I read that you can take the row covers off in the evening and replace them in late morning after the bees have had a chance to get to them. The other option is to pollinate yourself.

After the mess I've seen in my garden, I'd leave the row covers on until you are done with the harvest.

Wrap pantyhose around the stem of the plant. It may help stop or at least deter the SVB from burrying in.

I left my covers on until they started flowering and outgrowing the covers, and then took them off. I have gotten about MAYBE 10 zucchini out of 3 plants, but the SVBs have now gotten them! Very frustrating. I did plant a succession planting and hope I get more, but I wish I had planted them sooner and kept them better protected! Don't know what I am gonna do next year to try to beat these little buggers! This is my first experience with them, and growing squash other than pumpkins.

My Garden Blog

My plants are pretty huge now and am getting an average of 1-2 zucchini a day. It would be cumbersome to place row covers on the full-grown plants. The idea of putting panty hose on the stems sounds good. I have also heard of wrapping aluminum foil on the stems. I may do one or the other. I don't want to lose my crop.

I neglected to detect SVB, I saw the sawdust one morning and thought I need to check it out, well days later I did and had several SVB per plant, all of the root zones were hit, and several places through out the plant. I ripped out all my acorn squash and some volunteer pumpkins that I was letting go.

Next year I'll be sure to have BT on hand to try that early, didn't have money to even get some so just ripped out all the plants.

I'll also be growing butternut squash since I like that and it's supposed to be alot better, my cukes and watermelon didn't get any SVB.