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The objectives of this research were to stimulate and accelerate new growth in rooted cuttings of difficult-to-root woody plants, thereby increasing overwinter survival rates in the first propagation year. Etiolated and non-etiolated cuttings were taken from field grown stock plants of Acer rubrum `October Glory', Hamamelis vemalis, Hamamelis virginiana, and Stewartia pseudocamellia. After a 4 week etiolation period, during which the bases of new shoots were covered in black velcro bands, cuttings were taken in June, 1992 and dipped in one of three levels of IBA: 500, 1,000, 5,000 ppm for A. rubrum `October Glory', A. rubrum `Red Sunset', and H. vernalis, and 1,000, 5,000 and 10,000 ppm for H. virginiana and S. pseudocamellia. After 3 to 8 weeks under mist, successfully rooted plants were given 16 hour days with 70/60 F. D/N greenhouse temperatures. Plants were treated with a foliar spray of thidiazuron 50 mg/L, thidiazuron followed by GA 4/7 250 mg/L ten days later, silver thiosulfite (STS) 1%, or STS followed by GA_4/7 ten days later. Both STS and thidiazuron stimulated bud break in plants. After 4 weeks, plants were assessed for bud break, after which dormancy was induced under short days and cool temperatures (50/40 F. D/N). Once dormant, the plants' total growth and total nonstructural carbohydrates were measured, and plants were stored in 38 F. coolers for 3 months. At the end of 3 months, the plants were assessed for overwinter survival.

Budbreak inhibition and poor overwinter survival (OS) limit successful cutting propagation of Acer rubrum October Glory, A. rubrum Red Sunset, Hamamelis vernalis, H. virginiana and Stewartia pseudocamellia. Localized blanching (banding) of the cutting on the stock plant; a range of 3 IBA concentrations, and foliar spray application of: 1% silver thiosulfate(STS), STS followed ten days later by Gibberellin, GA_4/7:250ppm(STS GA),50ppm thidiazuron (TDZ) and TDZ followed by GA_4/7 (TDZ GA)were tested for increasing growth and overwinter survival.. Carbohydrates were analyzed in cuttings which did and didn't grow. A. rubrum October Glory^*, and Hamamelis spp all had increased OS for cuttings which grew. A. rubrum Red Sunset demonstrated a similar trend. Hamamelis spp. had significant increase in carbohydrates for cuttings which grew. A. rubrum October Glory' exhibited the same trend. S. pseudocamellia did not have increased OS with growth. and showed no increases in carbohydrates with growth, but the cuttings that didn't grow had at least 93 % more carbohydrates than the other species analyzed. All species had higher OS when stored in the 3° C cooler, than in the fluctuating cold frame. Banding increased growth of A. rubrum October Glory, and H. virginiana. IBA concentration affected growth of all species. STS increased growth of H. virginiana and S. pseudocamellia. GA_4/7 increased growth of all cuttings except A. rubrum October Glory.

Phytophthora cinnamomi Rands, the causal pathogen of phytophthora root rot (PRR) of chestnut, is one of the main obstacles to growth of american chestnut [Castanea dentata (Marsh.) Bork.] in the southern part of its distribution. To facilitate introgression of PRR resistance of chinese chestnut (C. mollissima Blume) into a C. dentata genetic background, we assessed the disease resistance of 10 interspecific hybrid families derived from potentially resistant C. mollissima cultivars. Hybrid progeny were inoculated with P. cinnamomi in the nursery and assessed for root lesion severity after 1 year of growth. Asymptomatic plants were transplanted to a P. cinnamomi-positive orchard and evaluated for survival midway through the following growing season. During the nursery experiment, 8 of 10 hybrid families were not significantly different from susceptible C. dentata controls for average disease resistance scores. However, multiple asymptomatic individuals were identified in each of the eight families. Two of the 10 hybrid families were not significantly different from the resistant C. mollissima and C. henryi controls. In the P. cinnamomi-positive orchard, the prescreened hybrid families displayed a greater proportion of survivors than backcross families that had not been prescreened for P. cinnamomi resistance. Hybrid plants that have survived 2 years of growth in P. cinnamomi-infested potting media and soils represent an important step toward the production of genetically diverse chestnut populations in the southeastern United States that combine the PRR resistance of C. mollissima with the morphology and local adaptation of C. dentata.