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Phillip C. Flanagan and W.T. Witte

Previous research at this facility has shown that copper sulfate, when incorporated with latex paint and applied to the interior surfaces of tube trays, was effective in chemically root pruning Quercus acutissima seedlings. Only 20% of deflected roots continued to grow after contacting Cu treated tube walls compared to controls. Treated plants showed a reduction of fibrous roots on the plug surface. Height and caliper were not affected by Cu treatments during chemical root pruning in the tube tray. Time required for regeneration of new roots was not affected by Cu treatments. Seedlings from each treatment were planted and grown two seasons under field conditions to observe effects on growth and root regeneration. No treatment effects occurred for height or caliper. Oak seedlings chemically root pruned with Cu exhibited more lateral growth and branching than control plants.

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Phillip C. Flanagan and W.T. Witte

Interior surfaces of tube trays were painted with white exterior acrylic latex paint and white interior latex paint containing 0, 50, or 300 gm/1 copper sulfate. Germinated Quercus acutissima seedlings were used to study chemical root pruning effects and subsequent root regeneration. After 16 weeks, only 0.73 roots per seedling continued growth after being deflected by the tubewall painted with 100gm/1 compared with 3.67 for the control. Fibrous roots were reduced when in contact with cu treated surfaces. Height and caliper were not affected at any treatment level. Three weeks after transplanting to larger untreated containers, height and caliper were still unaffected by any cu treatment. Time required for regeneration of new roots was not affected by cu treatments.

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R.N. Trigiano, M.T. Windham and W.T. Witte

Powdery mildew (Microsphaera pulchra) of flowering dogwood (Cornus florida L.) has become a significant problem of trees in nursery production as well as in the landscapes and forests of the eastern United States. The disease significantly reduces growth and berry production by older established trees and may contribute to the inability of younger trees (liners) in production to survive winter dormancy. Disease resistance in named cultivars is limited to partial resistance found in `Cherokee Brave'—all other cultivars are extremely susceptible. Until now, the only disease control measure was to establish an expensive, labor-intensive, preventive fungicide program. We examined >22,000 seedlings and identified 20 that were extremely resistant to powdery mildew. Three trees with white bracts were selected from the 20 and released as patent-pending cultivars. `Karen's Appalachian Blush' has long, non-overlapping, pink fringed bracts with a delicate appearance. `Kay's Appalachian Mist' has creamy white, slightly overlapping bracts with deeply pigmented clefts. `Jean's Appalachian Snow' has large, strongly overlapping bracts with non-pigmented clefts. The three powdery mildew-resistant cultivars will be entered into an existing breeding program with `Appalachian Spring', a cultivar released by the Tennessee Agriculture Experiment Station and resistant to dogwood anthracnose, in an attempt to produce trees that are resistant to both diseases.

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M.T. Windham, W.T. Witte and R.N. Trigiano

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W.T. Witte, R.J. Sauve and P.C. Flanagan

Eighty-one accessions of oak species, hybrids, and cultivars from commercially available sources were established at TSU-NCRS in Fall 1993 and Spring 1994, using 10 single-plant replications in a randomized complete block. Drip irrigation was begun on a regular basis May 1994, and plants were fertilized regularly. Height and diameter was recorded Fall 1994 and 1995. Fastest growing oaks in order of cm height growth increment over the two growing seasons were nigra, phellos, texana nuttalli, cerris, macrocarpa, falcata pagodaefolia, macrocarpa `Maximus', acutissima, austrina, shumardii, muehlenbergi, falcata, robur fastigiata, lyrata, virginiana, palustris, acutissima `Gobbler', glandulifera, macrocarpa `Ashworth', gambelli ×macrocarpa, alba. Most evergeen oaks did not survive Winter 1995–96, and data will be reported on winterkill.

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W.T. Witte, R.J. Sauve and P.C. Flanagan

Ten single plant replications of 11 taxa were planted 6 May 1994, fertilized regularly, and maintained under drip irrigation. Japanese beetle damage became apparent in mid-June. Sevin SL at 1 qt/100 gal was applied with a tractor-mounted mist blower on 22 June, and 7 and 19 July. Data on Japanese beetle populations were recorded using an arbitrary scale of 0 (no beetles) to 10 (heavy infestation). Damage on each tree was recorded using an arbitrary scale of 0 (no damage) to 10 (completely skeletonized). The annual increment in height and caliper growth was recorded for each tree in Fall 1994. Ulmus japonica and U. glabra `Pendula' had the most height growth (>60 cm increment) but were not significantly different from most other accessions, while NA 60070, U. crassifolia, and NA 60071 had significantly slower growth than the former group(<25 cm increment). Japanese beetles fed first on U. carpinifolia `Variegata', NA 60071, and 60070, skeletonizing most of the new growth before the first Sevin application, resulting in the most damage. This may have resulted in poor growth of the USDA/NA selections in 1994.

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W.T. Witte, R.J. Sauve and P.C. Flanagan

Several commercially available Acer saccharinum and A. negundo taxa were established with 10 single-plant replications in a cultivar trial at the TSU–NCRS in 1993 and 1994. Each plant was fertilized in spring and early summer with 100 gm 15–15–15 beginning Summer 1993. Drip irrigation was applied as needed beginning Summer 1993. Vegetation within tree rows was controlled with preemergent and postemergent herbicides, while grassed middles were mowed. Growth data were recorded in Fall 1993 and 1994 and height and caliper increment calculated for the 1994 season. In the silver maple group with most height growth were: `Silver Queen', `Skinneri', and `Silver Pyramid'. These differed significantly from a group of four slower growing cultivars. Cultivars with the most height growth also had the most caliper growth. Seedling boxelder grew faster than one accession of `Flamingo', while three other cultivars were intermediate. Data will also be presented on insect and disease ratings.

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W.T. Witte, R.J. Sauve and P.C. Flanagan

Commercially available Acer saccharum cultivars, and some closely related species accessions (floridanum, leucoderme, macrophyllum, and nigrum `Greencolumn'), were established as 10 single-plant replications in a cultivar trial at the TSU–NCRS in 1993 and Spring 1994. Plants were regularly fertilized and drip irrigation was begun Summer 1993. Growth data were recorded each fall and height and caliper increment calculated for the 1994 season. In the group with most height growth were: `Bonfire', `Majesty', nigrum `Greencolumn', leucoderme, `Sweet Shadow', `Fairview', and macrophyllum. These, except for `Fairview' and macrophyllum, differed significantly from a group of seven slower growing cultivars. With some exceptions, cultivars with the most height growth tended to have the most caliper growth, while those with the least height growth tended to have the least caliper growth. Data will also be presented on insect and disease ratings.

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W.T. Witte, R.J. Sauve and P.C. Flanagan

Commercially available Norway and sycamore maple taxa were established as 10 single-plant replications in a cultivar trial at the TSU–NCRS in 1993 and Spring 1994. Each plant was fertilized regularly and drip irrigation was begun Summer 1993. Vegetation within tree rows was controlled with preemergent and postemergent herbicides, while grassed middles were mowed. Growth data was recorded in Fall 1993 and 1994 and height and caliper increment calculated for the 1994 season. In this group of 29 taxa, 9 cultivars were in the group with most height growth: `Columnare', `Pond', `Deborah', `Crystal', `Parkway', `Columnarbroad', `Schwedleri', `Summershade', and `Fairview'. With some exceptions, cultivars with the most height growth tended to have the most caliper growth, while those with the least height growth tended to have the least caliper growth, with the notable exception of `Columnar'. Data will also be presented on insect and disease ratings.

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W.T. Witte, R.J. Sauve and P.C. Flanagan

Commercially available Acer rubrum and A. freemanii taxa were established as 10 single-plant replications in a cultivar trial at the TSU–NCRS in 1992 and Spring 1993. Plants were fertilized regularly and drip-irrigated as needed beginning Summer 1993. Growth data were recorded each fall and height and caliper increment calculated for the 1994 season. Ten cultivars were in the group with most height growth: `Armstrong', `Autumn Blaze', `Schlesingeri', `Olson', `Morgan', `Scarlet Red', `Embers', `Indian Summer', `Scarsen', and `October Glory'. These all differed significantly from a group of 11 slow-growing cultivars. With some exceptions, cultivars with the most height growth tended to have the most caliper growth, while those with the least height growth tended to have the least caliper growth. Data will also be presented on insect and disease ratings.