1. no above average rain. Although we just moved here in March; July was extremely hot, and I watered much more than in spring.
2. infestation identified as white flies and red mites, sprayed 4 times, but leaves keep dying and as I wrote before, now some grapes are shriveling;
3. very well established vines, per landlord; unfortunately the vines grow next to the supports for the deck, and the area is covered in river rock with soil in between. No 'basin' or circular area for watering. I water twice a week, per instructions from landlord.
THE PROBLEM, as I understand it, is that the landlord (lives in Oregon) did not remind the maintenance man to spray in the spring, to stay ahead of this infestation.