This report analyzes mortality data collected to test the effectiveness of the "Ezject'' herbicide lance developed by B. Dillistone. The lance injects a used .22 cartridge containing 0.22-0.24 g of the herbicide glyphosate into a tree. This method is fairly safe for the person applying the treatment and for the environment, since the herbicide is contained. The lance can also treat a large number of trees quickly.
Five trials were established in 1980 for western hemlock, Douglas-fir, and lodgepole pine. Initial dose-response models have been developed for western hemlock and Douglas-fir. Models could not be fit for lodgepole pine, however, because not enough large trees were treated and the treatments were confounded with other factors.
It is clear that the "Ezject'' lance injector system is effective for killing trees. Increasing the number of capsules or placing them around the tree increased the size of tree which could be killed. Seasonal effects were small in the long run. It is recommended that in future trials, individual trees be randomly assigned one of a wide range of dosages. The range of dosages should be chosen so that about half the treated trees survive the treatments. From this, proper operational guidelines for dosage prescriptions may be developed.
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Updated May 29, 2009