By David Elstein
October 23, 2002
When growing grapes for premium
wines--those that retail for more than $7 a bottle--growers need to make sure
that the grapes receive the optimum amount of irrigation water.
Agricultural Research Service scientists
are helping grape growers accomplish that goal.
ARS horticulturist Julie Tarara conducts research that helps growers in
numerous ways. Based in Pullman, Wash., Tarara works with the ARS
Crops Research Laboratory at Corvallis, Ore. She evaluates production
systems and determines irrigation water needs for grapevines, including those
grown in the desertlike areas of eastern Washington state. Premium wine grapes
are deliberately water-stressed to improve the quality of the fruit and of the
Growers use various types of irrigation systems--rill, sprinkler and drip.
Tarara conducts research on efficient irrigation systems, since water is
limited in eastern Washington and many groups want to use it. Her group
currently conducts research with a "sap flow gauge," a device that
measures the amount of water used by a grapevine. They have used the gauge
throughout the growing season to measure water use in both juice and wine
Besides the difference in water requirements, the vines are classified in
two different species and are farmed differently. Wine-grape vines typically
are smaller and produce less fruit than juice-grape vines. Many producers grow
both wine and juice grapes in addition to other fruits.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.