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32 W i n e s & V i n e s A P R i L 2 0 1 4 C alifornia and the other Pacific Coast states are facing an unprecedented drought. In Cal- ifornia, calendar year 2013 was the driest year on record. Many large reservoirs and ponds are very low, and numerous water providers are curtailing water deliveries to their cus- tomers. The period from Nov. 13, 2013, to Jan. 31, 2014, were the driest winter months on record since weather records have been kept in California. Even though some storms have occurred since then, con- tinued dryness and limited frost protection and irrigation water are likely to be issues for the 2014 growing season. The first steps Assessing your situation is very important in planning how to stretch water resources. How impacted is your water supply? If you are dependent on a surface supply such as a pond, what is its status as bud break begins? If you are part of an irrigation dis- trict, how much water are they planning on making available to their customers? How about your well? What is the level, and how likely is it to hold up during the year? Has it gone dry before? Since you are going to have to use water strategically, you will have to conserve water early for use later in the season, so you'd better have a good idea of how much water is available and how to use it proportionally to get the best yields and fruit quality with what you have to work with. The next consideration is your irrigation system. Be sure everything is functioning as well as is possible. Fix leaks, service fil- ters, flush the system, check pumps and pressure throughout the system, check emitter output and uniformity, and have the system tuned up to deliver water as efficiently and uniformly as possible. What is a winegrower to do? If you are facing a dry year with a limited water supply, you might be wondering how best to utilize your irrigation water. This article draws on the experiences of Austra- lian vignerons (wine grape growers) who faced devastating droughts in 2006-07 and learned useful irrigation strategies in a drought. The table below outlines the dif- ferent growth stages and the estimated amount of water used during each period. This table is a useful guide, but the amount of water for each growth stage has not been confirmed for the western United States. Remember, some of Australia is a virtual desert, and water is provided by irrigation districts. They often have to irrigate before bud break to ensure early season growth. For most of California, Vineyard Irrigation With a Limited Supply of Water Highlights • Limited frost protection and irrigation water are likely to be issues for the 2014 growing season in California. • The author, a university extension advisor, called on australian colleagues with recent drought experience to share water-saving strategies. • The article breaks down the growing season by vine growth stages and recommends smart practices for water application during each. Grounded Grapegrowing g L E N N M C g O u R t y Managing WatEr for groWth StagES growth Stage Water Management Percentage of total Water Used* Dormant rainfall, light irrigation Not needed most years in coastal California Bud break to flowering light to moderate irrigation, if no rain 9% Flowering to fruit set Irrigation critical for fruit set 6% Fruit set to véraison Hold back: practice rDI 35% Véraison to harvest Irrigate to keep the leaves on, ripen fruit 36% Harvest to leaf fall Nice to irrigate if you can 14% *Source: Clare regional Winegrape growers association, South australia, 2002