Vine weevil attacking my grapes!
I would continue with your Grape Vine. It is a bad year for Vine weevils this year with high numbers. They do not often attack Tomatoes or Peppers, so I am not surprised they are un-touched. You may need to keep repeating Vine weevil killer treatments for a while. Try to get an application applied in the next few weeks and then again in the spring. This will significantly reduce the Vine weevil larvae numbers in the soil or compost. The larvae will have likely weakened the roots and made the plant more prone to diseases.
Grapes are also prone to powdery mildew. You might want to consider applying some Fruits Boost, which contains Mycorrhiza fungi. This will help the roots develop and strengthen the plant. I hope this helps.