Rapid Screening of Young Oak Seedlings for Growth Potential

Growth rates of nursery-grown oaks are reported to vary considerably, and otherwise desirable species are not commonly grown because of slow growth when young. In this study, we investigated a method for rapid screening of very young oak seedlings for predicting potential for growth in a production nursery. Acorns from single maternal trees of Quercus montana Wild. (chestnut oak), Quercus palustris Münchh. (Pin Oak), Quercus velutina Lam. (Black Oak), and Quercus alba L. (White Oak) were collected from the campus of Virginia Tech in Blacksburg, VA in fall of 1999 and subjected to stratification at 5 °C for approximately 3 months. Single acorns were then planted in individual cells of 50-cell liner trays and grown in a heated greenhouse until at least 90% of individuals per species had set first buds. Height at first budset was recorded for individual seedlings. Trees were then transplanted into # 1 containers and grown outdoors at the Urban Horticulture Center near the Virginia Tech Campus until October, 2000,  at which time they were planted in single nursery rows with trees approximately 70 cm apart. All trees were grown in the ground for 3 additional growing seasons (= 4 total from seed), and final trunk diameters were measured 15 cm above ground level in February 2004. Species varied dramatically in growth over the four years. Chestnut Oak and Pin Oak had the greatest growth, followed by Black Oak and White Oak. Height at first budset was highly correlated with trunk diameter four years after planting for White Oak, but not Chestnut, Pin, or Black Oak. The utility of screening a group of germinated oak seedlings in this manner would therefore be species-specific and beneficial for White Oak production. White Oak is considered by most to be a superior adult tree but it is seldom available in the nursery trade because slow growth increases production costs for the finished product. Our data indicate that superior growth could be expected if, for example, 50% of the shorter plants were discarded at first budset during the propagation stage. Our data also indicate that Chestnut Oak grows as rapidly as the popular Pin Oak and may therefore be an alternative for this often over-planted species.