@article{hausle_forrester_walker_2023, title={Determining the effectiveness of using acoustic velocity as an indirect measurement of branchiness in standing longleaf pine}, volume={6}, ISSN={["1208-6037"]}, url={https://doi.org/10.1139/cjfr-2023-0052}, DOI={10.1139/cjfr-2023-0052}, abstractNote={ Branches reduce stem quality, and the level of the effect is determined by the geometry, size, and number, of associated knots. Quantifying branchiness is difficult, as visual estimates are subjective, and mechanical measurements are impractical. Acoustic velocity (AV) is a relatively novel measurement capturing the speed stress travels through wood. AV is correlated with wood stiffness and is affected by internal characteristics like knots. This project tested AV as an indirect branchiness metric by measuring AV, height, diameter, and counting branches classified by diameter on 255 standing 8 year old longleaf pine ( Pinus palustris). AV was highly correlated with height (r = 0.76, p < 0.0001) and slenderness (r = 0.52, p < 0.0001). AV was moderately correlated with large living branches (diameter > 2.54 cm) (r = −0.27, p < 0.0001), but not correlated with total branches. Height, slenderness, and the count of large living branches (diameter > 2.54 cm) were included in the selected model for AV. Inclusion of dead or small (diameter < 2.54 cm) branches reduced model power. The best model captured 11% of the variation in AV, of which branches explained 5%. We conclude that AV does not appropriately quantify individual tree branchiness, but may be suitable for comparing populations such as families or provenances. }, journal={CANADIAN JOURNAL OF FOREST RESEARCH}, author={Hausle, Jacks M. T. and Forrester, Jodi A. and Walker, Trevor D.}, year={2023}, month={Jun} }
 @article{lin_shalizi_walker_lauer_carrasco_gujjula_suren_isik_2023, title={Low-density AgriSeq targeted genotyping-by-sequencing markers are efficient for pedigree quality control in Pinus taeda L. breeding}, volume={19}, ISSN={["1614-2950"]}, url={https://doi.org/10.1007/s11295-023-01608-8}, DOI={10.1007/s11295-023-01608-8}, number={4}, journal={TREE GENETICS & GENOMES}, author={Lin, Yu-Ming and Shalizi, Mohammad Nasir and Walker, Trevor D. D. and Lauer, Edwin and Carrasco, Claudio D. D. and Gujjula, Krishna Reddy and Suren, Haktan and Isik, Fikret}, year={2023}, month={Aug} }
 @article{shalizi_walker_heine_payn_isik_bullock_mckeand_2023, title={Performance Based on Measurements from Individual-Tree Progeny Tests Strongly Predicts Early Stand Yield in Loblolly Pine}, volume={2}, ISSN={["1938-3738"]}, url={https://doi.org/10.1093/forsci/fxad002}, DOI={10.1093/forsci/fxad002}, abstractNote={Abstract}, journal={FOREST SCIENCE}, author={Shalizi, Mohammad Nasir and Walker, Trevor D. and Heine, Austin J. and Payn, Kitt G. and Isik, Fikret and Bullock, Bronson P. and McKeand, Steven E.}, year={2023}, month={Feb} }
 @article{shalizi_payn_walker_isik_heine_mckeand_2022, title={Long-term evaluation of intra- and inter-provenance hybrids of loblolly pine in the Piedmont region of the southeastern United States}, volume={522}, ISSN={["1872-7042"]}, url={http://dx.doi.org/10.1016/j.foreco.2022.120469}, DOI={10.1016/j.foreco.2022.120469}, abstractNote={Long-term response of two intra- and two inter-provenance populations of loblolly pine (Pinus taeda L.) were evaluated in the Piedmont region of the southeastern United States. In total, 82 polycross families of the Atlantic Coastal (C) and Piedmont (P) provenances (C×C, P×P) and their hybrids (C×P, P×C) were field tested for growth, sawtimber potential, and survival through age 19 years. The Coastal pure (C×C) families were the tallest, and the hybrid populations (C×P, P×C) were intermediate for height. The four populations did not differ for diameter at breast height. The hybrid C×P population, followed by the C×C population, showed significantly higher stand volumes per hectare. These two populations maintained higher survival and stand density compared to the Piedmont pure populations. Sawtimber potential was significantly higher in the Piedmont pure families at the coldest study sites, presumably due to defect in the C×C and C×P from cold damage. No significant genotype-by-environment interactions were detected for any traits. The genetic gain for height, stand volume, and survival was considerable in the C×C and C×P over the Piedmont source, suggesting potential for benefiting from the faster growth of the Coastal material in the Piedmont region. The performance of the Coastal intra- and inter-provenance populations was marginally affected by the minimum winter temperatures (MWT). These results indicate that the Coastal and the hybrid families can be planted in the Piedmont region with MWT’s of −13 °C or greater and where the difference in MWT between the origin of the Coastal parents and the test sites was not extreme (e.g., the difference did not exceed 2.8 °C). These MWT limits encompass the southern Piedmont of North Carolina (<35.615 °N) and the Piedmont of South Carolina, Georgia, and Alabama.}, journal={FOREST ECOLOGY AND MANAGEMENT}, publisher={Elsevier BV}, author={Shalizi, Mohammad Nasir and Payn, Kitt G. and Walker, Trevor D. and Isik, Fikret and Heine, Austin J. and McKeand, Steven E.}, year={2022}, month={Oct} }
 @article{heine_walker_jett_isik_mckeand_2022, title={Pollination Bag Type Affects Ovule Development and Seed Yields in Pinus taeda L.}, volume={12}, ISSN={["1938-3738"]}, url={https://doi.org/10.1093/forsci/fxac052}, DOI={10.1093/forsci/fxac052}, abstractNote={Abstract}, journal={FOREST SCIENCE}, author={Heine, Austin J. and Walker, Trevor D. and Jett, Jackson B. and Isik, Fikret and McKeand, Steven E.}, year={2022}, month={Dec} }
 @article{walker_cumbie_isik_2022, title={Single-Step Genomic Analysis Increases the Accuracy of Within-Family Selection in a Clonally Replicated Population of Pinus taeda L.}, volume={68}, ISSN={["1938-3738"]}, url={https://doi.org/10.1093/forsci/fxab054}, DOI={10.1093/forsci/fxab054}, abstractNote={Abstract}, number={1}, journal={FOREST SCIENCE}, publisher={Oxford University Press (OUP)}, author={Walker, Trevor D. and Cumbie, W. Patrick and Isik, Fikret}, year={2022}, month={Feb}, pages={37–52} }
 @article{lu_payn_pandey_acosta_heine_walker_young_2021, title={HYPERSPECTRAL IMAGING WITH COST-SENSITIVE LEARNING FOR HIGH-THROUGHPUT SCREENING OF LOBLOLLY PINE (PINUS TAEDA L.) SEEDLINGS FOR FREEZE TOLERANCE}, volume={64}, ISSN={["2151-0040"]}, url={http://dx.doi.org/10.13031/trans.14708}, DOI={10.13031/trans.14708}, abstractNote={Highlights}, number={6}, journal={TRANSACTIONS OF THE ASABE}, publisher={American Society of Agricultural and Biological Engineers (ASABE)}, author={Lu, Yuzhen and Payn, Kitt G. and Pandey, Piyush and Acosta, Juan J. and Heine, Austin J. and Walker, Trevor D. and Young, Sierra}, year={2021}, pages={2045–2059} }
 @article{pandey_payn_lu_heine_walker_acosta_young_2021, title={Hyperspectral Imaging Combined with Machine Learning for the Detection of Fusiform Rust Disease Incidence in Loblolly Pine Seedlings}, volume={13}, ISSN={["2072-4292"]}, url={https://www.mdpi.com/2072-4292/13/18/3595}, DOI={10.3390/rs13183595}, abstractNote={Loblolly pine is an economically important timber species in the United States, with almost 1 billion seedlings produced annually. The most significant disease affecting this species is fusiform rust, caused by Cronartium quercuum f. sp. fusiforme. Testing for disease resistance in the greenhouse involves artificial inoculation of seedlings followed by visual inspection for disease incidence. An automated, high-throughput phenotyping method could improve both the efficiency and accuracy of the disease screening process. This study investigates the use of hyperspectral imaging for the detection of diseased seedlings. A nursery trial comprising families with known in-field rust resistance data was conducted, and the seedlings were artificially inoculated with fungal spores. Hyperspectral images in the visible and near-infrared region (400–1000 nm) were collected six months after inoculation. The disease incidence was scored with traditional methods based on the presence or absence of visible stem galls. The seedlings were segmented from the background by thresholding normalized difference vegetation index (NDVI) images, and the delineation of individual seedlings was achieved through object detection using the Faster RCNN model. Plant parts were subsequently segmented using the DeepLabv3+ model. The trained DeepLabv3+ model for semantic segmentation achieved a pixel accuracy of 0.76 and a mean Intersection over Union (mIoU) of 0.62. Crown pixels were segmented using geometric features. Support vector machine discrimination models were built for classifying the plants into diseased and non-diseased classes based on spectral data, and balanced accuracy values were calculated for the comparison of model performance. Averaged spectra from the whole plant (balanced accuracy = 61%), the crown (61%), the top half of the stem (77%), and the bottom half of the stem (62%) were used. A classification model built using the spectral data from the top half of the stem was found to be the most accurate, and resulted in an area under the receiver operating characteristic curve (AUC) of 0.83.}, number={18}, journal={REMOTE SENSING}, publisher={MDPI AG}, author={Pandey, Piyush and Payn, Kitt G. and Lu, Yuzhen and Heine, Austin J. and Walker, Trevor D. and Acosta, Juan J. and Young, Sierra}, year={2021}, month={Sep} }
 @article{lu_walker_acosta_young_pandey_heine_payn_2021, title={Prediction of Freeze Damage and Minimum Winter Temperature of the Seed Source of Loblolly Pine Seedlings Using Hyperspectral Imaging}, volume={67}, ISSN={["1938-3738"]}, url={https://doi.org/10.1093/forsci/fxab003}, DOI={10.1093/forsci/fxab003}, abstractNote={Abstract}, number={3}, journal={FOREST SCIENCE}, publisher={Oxford University Press (OUP)}, author={Lu, Yuzhen and Walker, Trevor D. and Acosta, Juan J. and Young, Sierra and Pandey, Piyush and Heine, Austin J. and Payn, Kitt G.}, year={2021}, month={Jun}, pages={321–334} }
 @article{maynor_isik_walker_whetten_heine_payn_mckeand_2021, title={Provenance and Family Variation in Biomass Potential of Loblolly Pine in the Piedmont of North Carolina}, volume={67}, ISSN={["1938-3738"]}, url={https://doi.org/10.1093/forsci/fxaa056}, DOI={10.1093/forsci/fxaa056}, abstractNote={Abstract}, number={3}, journal={FOREST SCIENCE}, publisher={Oxford University Press (OUP)}, author={Maynor, Jessica A. and Isik, Fikret and Walker, Trevor D. and Whetten, Ross W. and Heine, Austin J. and Payn, Kitt G. and McKeand, Steven E.}, year={2021}, month={Jun}, pages={312–320} }
 @article{walker_bullock_smith_mckeand_2020, title={Modeling Self-Thinning Patterns in Loblolly Pine with Provenance and Family Effects}, volume={66}, ISSN={["1938-3738"]}, url={https://doi.org/10.1093/forsci/fxaa030}, DOI={10.1093/forsci/fxaa030}, abstractNote={Abstract}, number={6}, journal={FOREST SCIENCE}, publisher={Oxford University Press (OUP)}, author={Walker, Trevor D. and Bullock, Bronson P. and Smith, Benjamin C. and McKeand, Steven E.}, year={2020}, month={Dec}, pages={712–725} }
 @article{heine_walker_mckeand_jett_isik_2020, title={Pollination Bag Type Has a Significant Impact on Cone Survival in Mass Production of Controlled Pollinated Seeds in Loblolly Pine}, volume={66}, ISSN={0015-749X 1938-3738}, url={http://dx.doi.org/10.1093/forsci/fxaa013}, DOI={10.1093/forsci/fxaa013}, abstractNote={Abstract}, number={5}, journal={Forest Science}, publisher={Oxford University Press (OUP)}, author={Heine, Austin J and Walker, Trevor D and McKeand, Steven E and Jett, Jackson B and Isik, Fikret}, year={2020}, month={Jun}, pages={589–599} }
 @article{walker_isik_mckeand_2019, title={Genetic Variation in Acoustic Time of Flight and Drill Resistance of Juvenile Wood in a Large Loblolly Pine Breeding Population}, volume={65}, ISSN={0015-749X 1938-3738}, url={http://dx.doi.org/10.1093/forsci/fxz002}, DOI={10.1093/forsci/fxz002}, abstractNote={Abstract}, number={4}, journal={Forest Science}, publisher={Oxford University Press (OUP)}, author={Walker, Trevor D and Isik, Fikret and McKeand, Steven E}, year={2019}, month={Mar}, pages={469–482} }
 @article{walker_mckeand_2018, title={Fusiform Rust Hazard Mapping for Loblolly Pine in the Southeastern United States Using Progeny Test Data}, volume={116}, ISSN={["1938-3746"]}, DOI={10.5849/jof-2017-070}, number={2}, journal={JOURNAL OF FORESTRY}, publisher={Oxford University Press (OUP)}, author={Walker, Trevor D. and McKeand, Steven E.}, year={2018}, month={Mar}, pages={117–122} }