Test of a transpiration inhibitor on a forested watershed

The glyceryl half‐ester of decenylsuccinic acid (GlOSA) closes tree stomata when sprayed directly upon the undersides of leaves. Regression analysis of streamflow from two small watersheds at Coweeta showed that a 12% reduction in transpiration might be detected as a significant increase in streamflow. Two sprays of 50 pounds of GlOSA in water applied to 30 acres of one watershed from a helicopter produced little deposit on the undersides of leaves and no clear evidence of stomatal closure. Observed increases in streamflow were statistically insignificant.