What: For years, farmers and researchers have speculated about how tree root systems respond to varying degrees of water stress. While the effect of drought is easily observed in the tree's canopy of leaves and branches, the impact of insufficient water on the root system is hidden beneath several feet of soil. Some growers use backhoes to dig away the dirt, but this method is a rather crude approach to examining the tree's delicate root zone. Instead, Associate Professor Ken Shackel, a UC Davis scientist specializing in nut trees, is now making use of hydraulic technology to wash the soil away from growing almond trees and examine how four years of varied irrigation has impacted their roots. The study should provide a better understanding of the basic physiology of tree roots and give growers the information needed to make appropriate irrigation decisions. When: Tuesday, May 16, 8 a.m. to 4 p.m. Where: UC Davis Wolfskill Experimental Orchards, Winters Visuals: A fire hose and a large sewage-sludge truck will be used to simultaneously wash away the soil from tree roots and suck up the excess mud and water. The root system will be exposed to a depth of about 3 feet. Directions: From Sacramento, take Interstate 80 west to Highway 113. Drive north on Highway 113, taking the second exit at Russell Blvd. Drive west on Russell Blvd., which becomes Road 32. Continue toward Winters, crossing over Highway 505. Turn left at the first opportunity onto Road 89. Cross Putah Creek and immediately turn right onto Putah Creek Road. The Wolfskill Experimental Orchard is located on the left, past Winters Road and before Holmes Road. From San Francisco, take Interstate 80 east past Vacaville to Highway 505. Go north on Highway 505, exiting at Winters. Turn left onto Russell Blvd., which becomes Grant Street after you cross over Highway 505. Turn left at the first opportunity onto Road 89. Cross Putah Creek and immediately turn right onto Putah Creek Road. The Wolfskill Experimental Orchard is located on the left, past Winters Road and before Holmes Road.