Droopy Rosemary IV

Woe is my Rosemary for I hath believe it to be dead. :(
The development in the last few days is MAJOR powdery mildew almost like it was Christmas. It has completely defoliated my plant and now looks like an Oak in front of my house ;)
1. Can I cut this way back in hope it recoup from its stumps or is it dead dead dead? The root ball actually looks okay and no bugs that I can see, and the worms were in fact that.

It is rare that rosemary will come back from a setback like this. It is not impossible, but don't get your hopes up. I would prune back the dead, diseased foliage, and some of the stems. Don't cut back too much because some of the younger stems may still be alive and able to resprout.

2. I am now watching the rest of my plants for possible infection. Seems okay at this point except for one plant which I gave a baking soda spraying. Is this the proper method or do you recommend the soap douche :)

Baking soda with soap has some antifungal activity, particularly against powdery mildew. If that doesn't work, you can try hydrogen peroxide from your local pharmacy mixed with water at a proportion of 1 part hydrogen peroxide to two parts water. Dipping the entire above ground parts of the plant in a bucket with either the baking soda or peroxide solution is the best way to ensure that all leaf surfaces are treated.
The best approach is prevention. Powdery mildew usually means there is a problem with your watering or your ventilation. Try to improve the ventilation, using a fan if necessary, and try to water only in the morning so water does not remain on the foliage overnight.