Issue link: http://winesandvines.uberflip.com/i/66135
G r AP e G ro WING highlights • This overview of irrigation helps growers reassess how and when they irrigate grapevines. • The author explains evapotranspiration and how it relates to irrigation in gallons per vine. • Regulated deficit irrigation is explained and recommended as a way to save water and improve winegrape quality. sites it may take some thoughtful analysis and planning to produce balanced vines and quality fruit. Vigor can be addressed by using tools including planting compet- itive cover crops, designing the vineyard with a low vine density to allow for larger individual vines, divided canopy trellises and the use of low-vigor rootstocks such as 420A or riparia gloire. The object is to still maintain a high number of stems, ad- equate leaf area to ripen fruit, open cano- pies with good aeration and light flecks as well as a fruit-to-pruning weight ratio be- tween 4:1 and a maximum of 8:1 (accord- ing to experienced canopy management researchers such as Dr. Richard Smart.) There are also old head-pruned vine- yards planted on vigorous rootstocks (or their own roots in a few rare instances) that survive just fine with no irrigation, yielding low amounts of quality fruit when planted in the right locations. Overall, The climate at John Chiarito's Mendocino County vineyard lends itself to dry farming. non-irrigated vineyards represent a very small percentage of West Coast vineyards. (You can read about this in more detail in "Back to the Future: Dry Farming Vine- yards," Wines & Vines, February 2010.) Sprinkler irrigation In areas where frost protection is needed, overhead sprinklers are used when water is plentiful. Using sprinklers for irrigation can cause rot problems as the fruit ma- tures. Irrigation must be scheduled well in advance of ripening to avoid damage to grape clusters. Normally, sprinklers are run long enough to apply vine water needs three to five times per growing season. The last irrigation usually is applied at verai- son, just as the fruit is beginning to soften. Sprinkler irrigation requires considerable water compared to drip irrigation since the water is applied across the entire surface of the vineyard. Besides frost protection, it is useful to maintain perennial cover crops and provide heat cooling under very hot conditions with low humidity. Older vine- yards in California and desert areas such as the Columbia River Basin and the Oka- nagan Valley use sprinklers as their princi- pal irrigation method. Increasingly, most vineyards with sprin- kler systems have installed drip systems as well. Drip irrigation systems can place the Our expertise can mean your company's success. Benchmark Consulting provides human resources consulting and retained executive search services exclusively for the wine industry. 103 East Napa Street, Suite 1 ■ Sonoma, California 95476 ■ www.winecareers.com fx: 707.933.1508 tel: 707.933.1500 ■ Wines & Vines JUne 2011 81