I noticed some grape leaves undersides with raised green bumps all over, also showing on the front side. What could this be and how to treat. These are new vines this year, have been growing well till now. Hope you can help.
There are a number of possible insects or mites that infest grape leaves and cause misshaped growths. Without a photo to work from, I can only guess which one you are dealing with. One of the most common is grape phylloxera, a small aphid-like insect that causes uniquely shaped galls on the leaves a many varieties of grapes.
If this does not seem to match up with your situation, please send me some photos.
Yes, this is what is happening. I will call the County Extension office today. Will it spread to other healthy plants?
Grape phylloxera is a very complex situation. On some grape varieties the symptoms are all on the leaves and the plants can thrive even with lots of the galls. The insect also lives on the roots during different parts of its life cycle. Vitis vinifera grape varieties (European in origin, like Chardonnay, Riesling, etc.) are very susceptible to sever injury from the root infestations, while grape varieties with North American genetics are usually tolerant of the root infestations. It usually does spread within a planting, but not very quickly.