BT will take care of pickle worm problems quite well but the key is that it has to be started with the first blooms and repeated often, say every ten days or so; more often if it rains or you overhead water. Pickle worms present one big obstacle to sprays. It takes them less than a day to get inside the fruit where they are safe from sprays. You have to be sure there is BT residue on the fruit at all times so their first bite is their last and they never penetrate the fruit. BT never penetrates below the surface so it is easily washed off when you want to eat the fruit.

I could cry. I had a few squash plants that I have been nursing along with BT injections...even though there was some SVB damage, the plants themselves were looking quite good considering. I noticed that a couple of small fruit on which the blossoms were not even fully developed had started to turn brown. When I investigated, they were hollow...except for the pickle worm. :-( ARRRGGHHH!!

I had no idea that the worms were here already. B@$%@&*$!!!!

Now I am not sure about going to the bother with the cukes and tromboncinos....

I have to ask myself, is it worth all this hassle? The only thing that did decently this year were bell peppers and green beans.

We all have years like that. This is only an educated guess but your pickle worm problem may be related to your SVB problem. It has been observed many times that pests often prefer plants whose immune system has already been weakened by something else, in this case the SVB.

Thanks hoodat. You are probably right about the immune issue/SVBs. I really, really, really want to have some cukes and squash before the season is over, though. I'm thinking I may try the frequent BT sprays. How long does BT remain effective once it's mixed? Is it still alive/working after it gets stinky? I don't have many things to spray anymore, so a bottle of mixed spray may last a week or more...

BT is always stinky :D Once it's mixed with water it has to be used immediately. If you only have a few plants you can use one of those spray bottles a lot of products come in. That way you won't have to mix more than you need at a time.
Actually there are two types of BT spray. One type contains live bacillus and has to be stored carefully so they don't die. The advantage to this one is that you may create a "Typhoid Mary" effect where the disease is passed on from one caterpillar to others and spreads all over.
The other type contains only the toxin released by the BT bacillus and no live bacillus. The advantage here is that it will last longer even if not well stored. It works just as well but isn't passed on to other caterpillars. The manufacturer often doesn't specify which it is but the live bacillus costs a lot more. If it isn't specified on the label you almost certainly have the toxin.