Napa valley area, California US - July 13th, 2016.

Satellite NDVI and NDVI, in general, does not provide by itself data precise enough to be used in a precision viticulture project but it gives enough data to view where precise actions have to be performed. More precise data (various vegetation indices collected by UAV, soil analyses [not resistivity/conductivity],...) has to be collected and ground-truthed in the start of the precision viticulture project.
We have collected Landsat8 imagery and calculated several vegetation indices. Landsat8 multispectral imagery is available for free, its ground resolution is not very high (30 m per pixel) but it gives an idea about zones of high (green) vs low (red) NDVI values because these zones are mostly a little larger than this pixel size.

    red color corresponds to low NDVI/vigor
    green color corresponds to high NDVI/vigor
    Zoom in for more details.

The situation here is such that you can find relatively high vigour parcels because vineyards are irrigated. Too high vigour is likely to be detrimental to quality but when grapes coming from different parcels are mixed, the detrimental effect can be masked to a certain extent and the resulting wine can taste as relatively good quality. One concern, however, can be the long term quality.

Upon close examination, it appears that some parcels are "over-irrigated" because they exhibit too high vigour.
In some cases, vigour is restricted to a small zone within a parcel, which denotes that a perched water table might be present. Taking care of this situation would permit homogeneity in maturation and thus would be beneficial for the overall quality.