DDT accumulated over the past 20 years was detected in 22 of 23 pear orchard soils sampled in this Lake County survey. Two-thirds of the DDT was found in the top 6 inches of soil and 94% in the upper 12 inches of soil. Most pear roots in cultivated orchard soils are concentrated between the 1- and 4-ft depths.

Financial support was obtained from Pear Zone I and cooperation in the study was also received from many Lake County growers. This study was conducted as a part of the University of California Pear Decline Research Program.