City Trees is a premier publication focused on urban + community forestry. In each issue, you’ll learn how to best manage the trees in your community and more!
Issue link: https://read.dmtmag.com/i/1163463
www.urban-forestry.com 35 inoculated in the field (r = -0.75 ± 0.30) (Figure 2). This confirms that blight tolerance is cor- related in SSAs and field progeny tests. Early Screening of BC 3 F 2 Seedlings SSAs are also being tested as a method to screen large numbers of BC 3 F 2 seedlings prior to planting in seed orchards. BC 3 F 2 seedlings rated roughly equivalent to F1 controls would be planted in seed orchards. This method would allow more seedlings to be screened and require fewer trees planted in each plot, which in turn would allow for wider spacing than the standard seed orchard protocol. In 2018 TACF, in cooperation with the Virginia Department of Forestry, Maryland and Virginia Chapters of TACF, and Virginia Master Naturalists conducted experiments at the New Kent Forestry Center in New Kent, VA. Four-hundred-fifty seedlings from three BC 3 F 2 families and Chinese, American, and F1 controls were propagated in one-gallon containers and inoculated following standard SSA protocol. Cankers were assessed for twelve weeks. Resistance was measured by rating cankers on a 0-4 scale (0 = completely healed, 1 = a small, callused canker, 2 = a swollen and callused canker, 3 = a large, stroma-covered canker, and 4 = dead or dying seed- lings). Chinese chestnuts were the most resistant, American chestnuts were the least, and the F1 hybrids and three BC 3 F 2 families ranged from susceptible to intermediate resistance. Of the 120-150 seedlings screened per family in this study, approximately 20-45 seedlings would be selected for transplanting to the seed orchard based on these results. Proof of Concept? The BC 3 F 2 families screened at New Kent have been planted at the seed orchard at Eastern Kentucky University in Richmond, where they will be re-inocu- lated under standard field testing protocols in two to three years. Results will be compared to SSA results in order to determine if enough correlation exists between the two methods to rely on SSAs for early screening in seed orchard establishment. Additionally, in a 2017 experiment, two Maryland sources of BC 3 F 2 families were screened with SSAs and planted in seed orchards for long-term evaluations. These results provide reasonable assurance that SSAs can be useful for progeny tests, and poten- tially as an early screening tool. The use of SSAs by TACF chapters can save valuable resources such as the time and labor required to plant and manage seed orchards, as well as improve the quality of the trees established in our orchards. Volunteers help plant the BC 3 F 2 seedlings from the New Kent SSA program. These seedlings will be monitored for years and eventually re-screened for blight resistance. Volunteers at the New Kent Forestry Center tagging the seedlings with barcodes and prepping to ship to EKU to be planted in the seed orchard.