Principal Viticulturist Mark Greenspan, Ph.D. is an active author for wine industry publications. He has contributed a monthly column on timely viticultural topics to Wine Business Monthly continuously for 9 years (over 100 articles and counting!). 

Wine Business Monthly no longer provides links to individual articles. Articles may be found by following this link and typing "Greenspan" in the search box: Greenspan WBM Articles

Additional references: (Provided based on timeliness)

Using the Leaf Porometer in Grapes - a reference for using this valuable water status measuring device.

Shoot Tip Indicators for Early-Season Water Status Assessment

Mark hosts a video on vineyard water management for the Sonoma Winegrape Commission, funded by a USDA RMA Grant:
Insightful and Innovative Winegrowing
Advanced Viticulture, Inc.