ARS Helps Grape Growers

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 Horticultural 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 wine.

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 grapes.

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.