REPRODUCTION POTENTIAL AND NATURAL CANKER INFECTION ON BACKCROSSED CHESTNUT TREES 1

American chestnut (Castanea dentata Marsh. Borkh.) is a once- dominant hardwood species with the potential to be a valuable restoration tree for use on surface mined lands in the Appalachian region. Coupling soil ripping and plowing and disking with plantings of American and backcrossed chestnuts has resulted in high seedling survival on a reclaimed surface mine site in southeast Ohio. The objective of this study was to evaluate flowering, chestnut bur production (seed), and natural cankers caused by chestnut blight fungus (Cryphonectria parasitica) on three chestnut breeding lines, in three soil tillage treatments after seven field seasons. Pure American (Castanea dentata), and two types of C. dentata × C. mollissima hybrids (BC2F1 and BC3F1) were documented. Reproduction potential was measured via flower production in June. Canker incidence was recorded as necrotic bark lesions with the presence of orange spore bearing structures. When reproduction potential was compared among seed types, there were no differences; all chestnuts trees were flowering and producing chestnut burs after 7 seasons. Soil treatment had no impact on flowering incidence; however, hybrid breeding lines had a mild effect. Canker incidence and presence of flowers were not related statistically. When natural canker incidence was compared, pure American chestnut exhibited the most infection (P < 0.0001). There were also notable treatment effects, plots that applied the deep ripping had greater disease incidence on pure American chestnuts (P < 0.0001). Long-term survival and stand stability will depend on chestnut's tolerance to the blight at an age of fruiting and flowering. Results after seven years suggest that hybrids were exhibiting a decrease in blight incidence and were flowering and producing burs. Employing deep ripping methods to backcrossed American chestnut plantings provide a viable method for hardwood seedling establishment in soils impacted by surface mining.