- Andersen, Janet Lee
University of Maine Graduate School
Injection of elms with benzimidazoles is currently the most effective fungicidal control for Dutch elm disease. The injection process requires multiple wounds in trunk or root to inject fungicide into the tree. Each wound is a potential infection court for microorganisns, and benzirnidazole solutions cause some phytotoxicity to the woody tissues of the tree. Accordingly, this study was conducted to see how wounds respond in American elms after chemical injection. Forty-five small elms were injected with thiabendazole (TBZ), the solvent of TBZ, or water (15 trees of each); and the trees were removed for dissection at 4, 12, 16, 24 or 33 months after injection. In addition, 15 small elms were injected with TBZ on the 15th of each month from May to September (3 per month), and were removed one year later. All trees were dissected, length and volume of discolored wood for each wound were calculated, and isolations of microflora were made from areas of discolored wood. The anatomical and biochemical bases of the wound response were studied in 22 American elms 75 cm in diameter. Vessel and parenchyma tissues were evaluated for each tree from samples collected and prepared for microscopic examination.