hi there... i don't know if this will be much help to you, but i use a mixture of water and dishsoap, and spray it on my plants, in the late evening. it makes the plant too slippery for the flies. in my opinoin, it works. you are not supposed to use pesticides on anything that you want to eat, plus it usually kills benifical insects as well. good luck.

kim

Also keep an eye open for skeletonizers... black flies that that destroy the vine... they also have larvae all over that look like pretty yellow and purple caterpillars but they bite... my mom and I just picked a bunch of grape leaves today and made dolma (heck, I can't spell it)... mmmmm
Brittany

oh, i almost forgot... i also mix earthworm casting into the soil around the plants. it gets absorbed into the plant and the whitefies hate the way the plant tastes.

Did you ever get rid of them for the next year? Did you treat the vine during winter at all or the soil. I had the same thing happen to me this year and I dont know what to do this winter or how i can prevent these white flies from coming back. It was a nightmare and my vines looked so bad and my grapes never turned purple but stayed green but ripe. What should i do to prevent and treat this winter before next spring michelle.bordirestoration@gmail.com

This cannot be a new thing. I too have a one year old vine, no fruit, lots of vine and millions of those very, very small flying insects. Shake the plant and these things swam out like some kind of plague -- but try to find them on the underside of the leaves -- they are not impossible to see but if they do not move you can miss them, unless they fly, then they are truly evident. Also, the leaves now have brown blotches all over them and some are skeletal -- not sure these flies or whatever, are the cause but there are so many that they cannot be beneficial. But, no one seems to have and answer, like this is something unusual. Strange, no one seems to have a solid answer?