What causes a grapevine to actually drip water from its vine?

Question

In the past these grapes have produced nicely and looked great. This year the branches seem to 'snap off ' easily and then drip fluid (looks just like water-not sticky, no smell). The only difference this year is an automatic watering system- are they getting too much water?

Answer 1

I don't really know what it is that you are describing, but the links below may help you to determine whether or not you are watering too much.
http://www.fao.org/ag/AGL/aglw/cropwater/grape.stm#scheduling

"The amount of water that grapevines require varies with their age, amount of fruit produced, presence of competitive weeds, and humidity. Mature vines can use the equivalent of 24 to 30 inches of rainfall per year, or 30 or more gallons of water per vine per week in the heat of the growing season (Lakso and Pool, 2001). Mild to moderate drought stress after veraison (onset of final stage of fruit ripening) can help slow vegetative growth and concentrate grape flavors. More severe drought stress, however, leads to reduced carbohydrate (e.g., sugars) production, poor fruit and wine quality, reduced vine vigor, and diminished yields."
http://www.ext.vt.edu/pubs/viticulture/463-020/463-020.html
Happy Vineyarding!