To increase grafting success rate, a hot callus grafting system was designed and implemented as part of a multiagency collaborative project to manage beech bark disease (BBD) through the establishment of regional BBD-resistant grafted seed orchards. Five years of data from over 2000 hot callus graft attempts were analyzed using a logistic regression model to determine which factors were important in graft success. Variables having the largest influence included scion genotype, technical problems, health issues (such as chlorosis or dwarfing), and contamination. Very few genotypes had significantly lower success compared with the average genotype, indicating that this method should be widely applicable. Comparison of the hot callus method with traditional grafting demonstrated that the odds of success using the hot callus method were 17 times greater than traditional grafting methods. Hot callus grafting is an efficient method for propagating American beech selections resistant to BBD for the establishment of seed orchards and superior clones with value as ornamentals.
David W. Carey, Mary E. Mason, Paul Bloese and Jennifer L. Koch
Raymond O. Miller, Paul D. Bloese, James W. Hanover and Robert A. Haack
A test of Michigan half-sib progeny of paper birch (Betula papyrifera Marsh.) and European white birch (B. pendula Roth.) was conducted in Michigan to examine species variation in growth, bark color, and resistance to bronze birch borer (Agrilus anxius Gory). Paper birch was superior to European white birch in height and borer resistance at age 12 years from seed. Families of paper birch were identified that grew exceptionally well, had developed white bark within 6 years, and exhibited borer resistance. The magnitude of additive genetic variance and narrow-sense family heritability estimates for paper birch indicated that sufficient genetic variation and inheritance exist to support selection and breeding for height. Paper birch may be an acceptable substitute for European white birch as a landscape species in northeastern North America.