Structural and Biological Effects of Trunk Injected Paclobutrazol in Yellow Poplar    (View PDF)

Ronald E. Zillmer, William R. Chaney and Harvey A. Holt

Abstract: Sixty-three yellow poplar {Liriodendron tulipifera) trees, 5-11 indbh.wereselectedinaplantationatthe Martell Experimental Forest, Purdue University. Three trunk injection treatments were applied to three groups of 21 trees in June, 1989. Treatments consisted of injecting, at a pressure of 60 psi, 40 ml per injection hole of 1) Clipper 20 UL, 2) methanol with methylene blue dye (0.3% solution), or 3) water. The occurrence and duration of weeping from injection holes were evaluated. Sample trees from each treatment were harvested and the trunk dissected into both longitudinal and transverse sections 4 and 12 months after injection. The distance that wood discoloration or dye staining extended both above and below the injection sites and the volume of sapwood affected were substantially greater in trees injected with Clipper 20 UL or methanol/methylene blue than in trees injected with water. Closure of injection wounds was influenced by cambial and phloem dieback that resulted in nonuniform callus growth and incomplete closure of most wounds 12 months after treatment.

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https://doi.org/10.48044/jauf.1991.060