Bt is a bacteria that you spray on the grape leaves. You have to get the entire leaf. When the catipillars hatch, they eat the BT when they eat the leaves and they die. It takes a few days. I spray every week. It's best to spray in the evening because the sunlight breaks it down. Here is one version http://www.saferbrand.com/store/garden-care/5162, I use the liquid version from Lowes (same brand). It only takes a small amount diluted in a spray bottle. At some point a pump sprayer would be much easier. I usually do the undersides of the leaves first, and then the tops. That way you don't have it dripping on you when you are doing the bottom sides. It's safe for the chickens to eat the leaves too.What is bt? I haven't seen any of the buggers on mine yet but I'd like to be prepared. Last year I just cut individual leaves off and stuck them in the sun to squirm and die.
