@article{woodard_schultheis_jennings_woodley_suchoff_2024, title={Horizontal Planting Orientation Can Improve Yield in Organically Grown Sweetpotato}, volume={59}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI17352-23}, abstractNote={Sweetpotato [Ipomoea batatas (L.) Lam.] is one of North Carolina’s (USA) most important organic commodity crops; however, yields tend to be less when compared with conventionally produced sweetpotato. Standard field establishment uses unrooted stem cuttings that are transplanted vertically in the soil. Producers in other countries typically use other planting orientations, including cuttings transplanted horizontally. Empirical evidence from North Carolina, USA, sweetpotato producers suggests that a horizontal orientation may improve yields. An organically managed field study using ‘Monaco’ sweetpotato was conducted in 2020 and 2021 in Bailey, NC, USA. The study evaluated stem cutting planting orientations (vertical, sleeve, horizontal), stem cutting length (25 cm and 38 cm), and harvest time (early or late) in a full-factorial randomized complete block design. In 2020, marketable yields were 16% greater for the horizontal orientation compared with the vertical orientation, with intermediate yields using the sleeve attachment. However, in 2021, there were no differences in marketable yield among planting orientations. In both years, US No. 1–grade yields were significantly greater when cuttings were planted horizontally compared with vertically, with an average increase of 18%. Delaying harvest until ∼126 days is recommended to increase yields for ‘Monaco’, regardless of planting orientation. This study provides evidence that a horizontal planting orientation could increase premium root yields and improve land-use efficiency for organically produced sweetpotatoes.}, number={1}, journal={HORTSCIENCE}, author={Woodard, Alyssa J. and Schultheis, Jonathan R. and Jennings, Katherine M. and Woodley, Alex L. and Suchoff, David H.}, year={2024}, month={Jan}, pages={36–42} }
 @article{veazie_jeong_jackson_suchoff_whipker_2024, title={Peat Substrates Amended with Wood-based Biochar Do Not Influence the Efficacy of Paclobutrazol Drenches}, volume={59}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI17621-23}, abstractNote={Various soilless substrate components have been evaluated for many years to identify sustainable resources that do not negatively impact plant growth. Biochar is a carbon-based material that has been evaluated for use as an alternative aggregate in peat-based soilless substrates. In addition, the use of carbon adsorption for compound removal is widely used in groundwater remediation, municipal water filtration, and volatile organic compounds. Experiment one aimed to determine the impact of coarse biochar (<6 mm) on paclobutrazol efficacy when incorporated at 15% or 30% by volume in a peat-based substrate when compared with a perlite-amended substrate at the same incorporation volumes. In Expt. 1, a single paclobutrazol drench application of 0, 0.5, 1.0, 2.0, and 4.0 mg·L−1 was applied to ‘Princettia Red’ and ‘Princettia White’ poinsettias (Euphorbia pulcherrima × Euphorbia cornastra). In Expt. 2, two different biochar particle sizes of coarse (<6 mm) and extra coarse (>6 mm) were examined at the same incorporation volumes as Expt. 1 and compared with a perlite-amended substrate at the same incorporation volumes. However, during Expt. 2, continual drench applications at times of irrigation of 0.0, 6.25, 12.5, 25.0, 50, and 100 μg·L−1 (ppb) paclobutrazol were applied to pansy (Viola ×wittrockiana) ‘Matrix Blue Blotch’ and begonia (Begonia ×hybrida) ‘Big Red Bronze Leaf’. The efficacy of paclobutrazol drenches for controlling growth in all species was unaffected by the substrate composition regarding aggregate type or aggregate incorporation rate. Thus, even though biochar is often used for bioremediation and wastewater treatment, it did not negatively impact the efficacy of paclobutrazol drenches at the concentrations used. This research suggests that when biochar is used as an amendment to peatmoss it will not influence paclobutrazol drench efficacy when incorporated up to 30% by volume for the examined species.}, number={2}, journal={HORTSCIENCE}, author={Veazie, Patrick and Jeong, Ka Yeon and Jackson, Brian and Suchoff, David and Whipker, Brian E.}, year={2024}, month={Feb}, pages={248–254} }
 @article{owen_suchoff_chen_2023, title={A Novel Method for Stimulating Cannabis sativa L. Male Flowers from Female Plants}, volume={12}, ISSN={["2223-7747"]}, url={https://www.mdpi.com/2223-7747/12/19/3371}, DOI={10.3390/plants12193371}, abstractNote={Female hemp plants are desired in floral hemp operations due to their higher cannabinoid contents. To produce feminized seeds, a critical step of inducing fertile male flowers on female plants is performed. In feminized seed production, freshly mixed STS (silver thiosulfate + sodium thiosulfate) is applied to female plants as an ethylene inhibitor to induce male flowers. However, the short-shelf stability of the STS buffer can cause difficulty in the application and inconsistent results. Alternative methods with improved accessibility and stable buffers will be beneficial for the hemp industry and hemp breeders. A commercially available floriculture product, Chrysal ALESCO®, contains silver nitrate, the same active ingredient as STS but with increased shelf stability. This study compares Chrysal ALESCO® to the traditional STS standard methods for male flower induction on female plants and their pollen quality. The two treatments were applied to six female hemp accessions with three replicates investigated, and the male flower counts and pollen quality were compared. No statistically significant difference was discovered in their male flower counts; the STS-treated plant produced an average of 478.18 male flowers, and the Chrysal ALESCO®-treated plant produced an average of 498.24 male flowers per plant. Fluorescein diacetate (FDA) and acetocarmine stains were used to investigate the pollen quality (non-aborted rate) of two chosen genotypes. FDA-stained pollen of Chrysal ALESCO® showed a significantly higher non-aborted rate than the pollen of traditional STS-treated plants (p < 0.001); however, only a marginally higher non-aborted rate was discovered by acetocarmine staining (p = 0.0892). In summary, Chrysal ALESCO® performed equally to traditional STS treatment at male flower counts and better or equally in pollen quality. With better shelf stability and easy application, ALESCO® can be a viable alternative option for stimulating male flowers on female hemp plants.}, number={19}, journal={PLANTS-BASEL}, author={Owen, Luke and Suchoff, David and Chen, Hsuan}, year={2023}, month={Oct} }
 @article{kirk_henson_seevers_liu_west_suchoff_yin_2023, title={A critical review of characterization and measurement of textile-grade hemp fiber}, volume={7}, ISSN={["1572-882X"]}, DOI={10.1007/s10570-023-05420-4}, journal={CELLULOSE}, author={Kirk, H. and Henson, C. and Seevers, R. and Liu, Y. and West, A. and Suchoff, D. and Yin, R.}, year={2023}, month={Jul} }
 @article{barnes_parajuli_leggett_suchoff_2023, title={Assessing the financial viability of growing industrial hemp with loblolly pine plantations in the southeastern United States}, volume={6}, ISSN={["2624-893X"]}, DOI={10.3389/ffgc.2023.1148221}, abstractNote={Industrial hemp (Cannabis sativa L. <0.3% THC), a non-psychoactive chemotype of cannabis, was reclassified and made legal for growing across the United States under the 2018 Farm Bill. Given that resources, knowledge, and interest for this novel crop are expanding rapidly, we explored the possibility of intercropping industrial hemp for fiber with loblolly pine (Pinus taeda) plantations, one of the most commercially widespread tree species in the southern United States. Following a previous greenhouse study confirming hemp’s ability to grow in pine-influenced soils, we examined the financial feasibility of this potential agroforestry system. We simulated the loblolly pine tree growth information using PTAEDA 4.0, a growth and yield model, and collected the enterprise budget data on hemp productivity, operating and fixed costs, and prices from various sources. Based on the capital budgeting analyses, results suggest that pine-hemp intercropping can yield higher economic returns –at least 25% higher net present value—than the conventional monoculture loblolly pine plantation. The early rotation cash flow and the complimentary benefits can result in a more financially viable loblolly pine plantation under the intercropping scenario. While new research continues to advance further with field trials and other analyses, this study provides valuable insights into the current market conditions and productivity level of industrial hemp cultivation that need to be addressed for hemp intercropping to succeed as an economically viable agroforestry investment.}, journal={FRONTIERS IN FORESTS AND GLOBAL CHANGE}, author={Barnes, Thomas and Parajuli, Rajan and Leggett, Zakiya and Suchoff, David}, year={2023}, month={May} }
 @article{brym_philpott jr_rheay_monserrate_bernstein_chase_ellison_shock_smart_stack_et al._2023, title={Hemp Morphology and Physiology Standards for Research and Industry Applications}, volume={58}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI17093-23}, abstractNote={Hemp (Cannabis sativa L.) research and commercial production has recently experienced a global revival motivated by passage of laws reversing long-standing prohibitions and by expansion in markets. Collaborative research has been initiated in response to renewed interest in hemp production, such as the American Society for Horticultural Science Hemp Research and Extension Professional Interest Group (ASHS Hemp). Collaborators new to this crop have identified a lack of standard definitions, descriptions, and procedures for cohesive study specific to hemp production. Standards are necessary for synthesis of data gathered across research and industry programs. ASHS Hemp convened a workshop of hemp researchers and industry representatives to establish consensus on a minimum set of standards for research data and industry assessments. The resulting morphology and physiology standards developed at the workshop are presented here with a focus on plant height, flowering time, and crop quality. Plant height was defined as the vertical distance between the root crown at the soil surface and the stem node (or tip) of the apical meristem of the tallest branch. Plant height was importantly distinguished from stem length and canopy height, which may differ based on pruning and management of the plant. Flowering time was defined to indicate date of initiation of inflorescence development as the earliest day terminal flowering clusters appear visually. Flowering time was distinguished from solitary flowering behavior and floral maturity. Crop quality was determined to be a feature that should be established first by industry based on market standards and then subsequently adopted by researchers targeting outcomes in specific areas. A standard moisture content for dry flower, seed, and straw must be established. A moisture content of 10% to 12% was identified as a current standard for floral yield, whereas 8% was identified as a moisture content standard for seed crops. Bast-to-hurd ratio and decortication efficiency were fiber quality metrics identified for minimum standards, and thousand seed weight, protein content, oil content, and oil composition were considered for minimum seed quality standards. The hemp research community is well positioned to standardize genomic references and establish best management practices for production targets. These efforts would be assisted by the adoption of the proposed standard definitions, descriptions, and procedures decided by consensus at the ASHS Hemp 2022 workshop.}, number={7}, journal={HORTSCIENCE}, author={Brym, Zachary T. and Philpott Jr, Steven C. and Rheay, Hanah and Monserrate, Luis A. and Bernstein, Nirit and Chase, Carlene A. and Ellison, Shelby L. and Shock, Clinton C. and Smart, Lawrence B. and Stack, George M. and et al.}, year={2023}, month={Jul}, pages={756–760} }
 @article{james_vann_suchoff_mcginnis_whipker_edmisten_gatiboni_2023, title={Hemp yield and cannabinoid concentrations under variable nitrogen and potassium fertilizer rates}, volume={4}, ISSN={["1435-0653"]}, url={https://doi.org/10.1002/csc2.20966}, DOI={10.1002/csc2.20966}, abstractNote={Abstract}, journal={CROP SCIENCE}, author={James, Maggie S. and Vann, Matthew C. and Suchoff, David H. and McGinnis, Michelle and Whipker, Brian E. and Edmisten, Keith L. and Gatiboni, Luciano C.}, year={2023}, month={Apr} }
 @article{machanoff_vann_woodley_suchoff_2022, title={Evaluation of conservation tillage practices in the production of organic flue-cured tobacco}, volume={5}, ISSN={["2639-6696"]}, url={https://doi.org/10.1002/agg2.20317}, DOI={10.1002/agg2.20317}, abstractNote={Abstract}, number={4}, journal={AGROSYSTEMS GEOSCIENCES & ENVIRONMENT}, author={Machanoff, Cordelia H. and Vann, Matthew Christopher and Woodley, Alex L. and Suchoff, David}, year={2022} }
 @article{machanoff_vann_woodley_suchoff_2022, title={Evaluation of the use of polyethylene mulches in the production of organic flue-cured tobacco}, volume={7}, ISSN={["1435-0645"]}, url={https://doi.org/10.1002/agj2.21100}, DOI={10.1002/agj2.21100}, abstractNote={Abstract}, journal={AGRONOMY JOURNAL}, author={Machanoff, Cordelia A. and Vann, Matthew Christopher and Woodley, Alex L. and Suchoff, David}, year={2022}, month={Jul} }
 @article{lu_young_linder_whipker_suchoff_2022, title={Hyperspectral Imaging With Machine Learning to Differentiate Cultivars, Growth Stages, Flowers, and Leaves of Industrial Hemp (Cannabis sativa L.)}, volume={12}, ISSN={["1664-462X"]}, DOI={10.3389/fpls.2021.810113}, abstractNote={As an emerging cash crop, industrial hemp (Cannabis sativa L.) grown for cannabidiol (CBD) has spurred a surge of interest in the United States. Cultivar selection and harvest timing are important to produce CBD hemp profitably and avoid economic loss resulting from the tetrahydrocannabinol (THC) concentration in the crop exceeding regulatory limits. Hence there is a need for differentiating CBD hemp cultivars and growth stages to aid in cultivar and genotype selection and optimization of harvest timing. Current methods that rely on visual assessment of plant phenotypes and chemical procedures are limited because of its subjective and destructive nature. In this study, hyperspectral imaging was proposed as a novel, objective, and non-destructive method for differentiating hemp cultivars, growth stages as well as plant organs (leaves and flowers). Five cultivars of CBD hemp were grown greenhouse conditions and leaves and flowers were sampled at five growth stages 2–10 weeks in 2-week intervals after flower initiation and scanned by a benchtop hyperspectral imaging system in the spectral range of 400–1000 nm. The acquired images were subjected to image processing procedures to extract the spectra of hemp samples. The spectral profiles and scatter plots of principal component analysis of the spectral data revealed a certain degree of separation between hemp cultivars, growth stages, and plant organs. Machine learning based on regularized linear discriminant analysis achieved the accuracy of up to 99.6% in differentiating the five hemp cultivars. Plant organ and growth stage need to be factored into model development for hemp cultivar classification. The classification models achieved 100% accuracy in differentiating the five growth stages and two plant organs. This study demonstrates the effectiveness of hyperspectral imaging for differentiating cultivars, growth stages and plant organs of CBD hemp, which is a potentially useful tool for growers and breeders of CBD hemp.}, journal={FRONTIERS IN PLANT SCIENCE}, author={Lu, Yuzhen and Young, Sierra and Linder, Eric and Whipker, Brian and Suchoff, David}, year={2022}, month={Feb} }
 @article{lu_li_young_li_linder_suchoff_2022, title={Hyperspectral imaging with chemometrics for non-destructive determination of cannabinoids in floral and leaf materials of industrial hemp (Cannabis sativa L.)}, volume={202}, ISSN={["1872-7107"]}, DOI={10.1016/j.compag.2022.107387}, abstractNote={With the passage of the 2018 Farm Bill, industrial hemp (Cannabis sativa L.) has become a legal and economically promising crop commodity for U.S. farmers. There has been a surge of interest in growing industrial hemp for producing cannabinoids, such as cannabidiol (CBD), because of their medical potential. Quantitative determination of cannabinoids in harvested materials (primarily floral tissues) is critical for cannabinoid production and compliance testing. The concentrations of cannabinoids in hemp materials are conventionally determined using wet-chemistry chromatographic methods, which require destructive sampling, and are time-consuming, costly, and thus not suitable for on-site rapid testing. This study presents a novel effort to utilize hyperspectral imaging technology for non-destructive quantification of major cannabinoids, including CBD, THC (tetrahydrocannabinol), CBG (cannabigerol) and their acid forms in fresh floral and leaf materials of industrial hemp on a dry weight basis. Hyperspectral images in the wavelength range of 400–1000 nm were acquired from floral and leaf tissues immediately after harvest from a total of 100 industrial hemp plants of five cultivars at varied growth stages. Linear discriminant analysis showed hyperspectral imaging could identify CBD-rich/poor and THC-legal/illegal flower samples with accuracies of 99% and 97%, respectively. Quantitative models based on full-spectrum PLS (partial least squares) achieved prediction accuracies of RPD (ratio of prediction to deviation) = 2.5 (corresponding R2 = 0.84) for CBD and THC in floral tissues. Similar accuracies were obtained for their acid forms in flower samples. The predictions for CBG and its acid form in floral tissues and all six cannabinoids in leaf tissues were unsatisfactory with noticeably lower RPD values. Consistently improved accuracies were obtained by parsimonious PLS models based on a wavelength selection procedure for minimized variable collinearity. The best RPD values of approximately 2.6 (corresponding R2 = 0.85) were obtained for CBD and THC in floral materials. This study demonstrates the utility of hyperspectral imaging as a potential valuable tool for rapid quantification of cannabinoids in industrial hemp.}, journal={COMPUTERS AND ELECTRONICS IN AGRICULTURE}, author={Lu, Yuzhen and Li, Xu and Young, Sierra and Li, Xin and Linder, Eric and Suchoff, David}, year={2022}, month={Nov} }
 @article{kulesza_manning_vann_suchoff_woodley_mcginnis_2022, title={Organic nitrogen fertilizer sources for field production of flue-cured tobacco (Nicotiana tabacum L.)}, volume={2}, ISSN={["1435-0645"]}, url={https://doi.org/10.1002/agj2.20989}, DOI={10.1002/agj2.20989}, abstractNote={Abstract}, journal={AGRONOMY JOURNAL}, publisher={Wiley}, author={Kulesza, Stephanie B. and Manning, Nicholas J. and Vann, Matthew C. and Suchoff, David H. and Woodley, Alexander L. and McGinnis, Michelle M.}, year={2022}, month={Feb} }
 @article{linder_young_li_inoa_suchoff_2022, title={The Effect of Harvest Date on Temporal Cannabinoid and Biomass Production in the Floral Hemp (Cannabis sativa L.) Cultivars BaOx and Cherry Wine}, volume={8}, ISSN={["2311-7524"]}, url={https://doi.org/10.3390/horticulturae8100959}, DOI={10.3390/horticulturae8100959}, abstractNote={The objectives of this study were to model the temporal accumulation of cannabidiol (CBD) and tetrahydrocannabinol (THC) in field-grown floral hemp in North Carolina and establish harvest timing recommendations to minimize non-compliant crop production. Field trials were conducted in 2020 and 2021 with BaOx and Cherry Wine cultivars. Harvest events started two weeks after floral initiation and occurred every two weeks for 12 weeks. Per-plant threshed biomass accumulation exhibited a linear plateau trend. The best fit model for temporal accumulation of THC was a beta growth curve. As harvest date was delayed, total THC concentrations increased until concentrations reached their maximum, then decreased as plants approached senescence. Logistic regression was the best fit model for temporal accumulation of CBD. CBD concentrations increased with later harvest dates. Unlike THC concentrations, there was no decline in total CBD concentrations. To minimize risk, growers should test their crop as early as possible within the USDA’s 30-day compliance window. We observed ‘BaOx’ and ‘Cherry Wine’ exceeding the compliance threshold 50 and 41 days after flower initiation, respectively.}, number={10}, journal={HORTICULTURAE}, author={Linder, Eric R. and Young, Sierra and Li, Xu and Inoa, Shannon Henriquez and Suchoff, David H.}, year={2022}, month={Oct} }
 @article{linder_young_li_inoa_suchoff_2022, title={The Effect of Transplant Date and Plant Spacing on Biomass Production for Floral Hemp (Cannabis sativa L.)}, volume={12}, ISSN={["2073-4395"]}, url={https://doi.org/10.3390/agronomy12081856}, DOI={10.3390/agronomy12081856}, abstractNote={Floral hemp cultivated for the extraction of cannabinoids is a new crop in the United States, and agronomic recommendations are scarce. The objective of this study was to understand the effects of plant spacing and transplant date on floral hemp growth and biomass production. Field trials were conducted in North Carolina in 2020 and 2021 with the floral hemp cultivar BaOx. Transplant date treatments occurred every two weeks from 11 May to 7 July (±1 d). Plant spacing treatments were 0.91, 1.22, 1.52, and 1.83 m between plants. Weekly height and width data were collected throughout the vegetative period, and dry biomass was measured at harvest. Plant width was affected by transplant date and spacing. Plant height was affected by transplant date. Earlier transplant dates resulted in taller, wider plants, while larger plant spacing resulted in wider plants. Individual plant biomass increased with earlier transplant dates and larger plant spacing. On a per-hectare basis, biomass increased with earlier transplant dates and smaller transplant spacing. An economic analysis found that returns were highest with 1.22 m spacing and decreased linearly by a rate of −163.098 USD ha−1 d−1. These findings highlight the importance of earlier transplant timing to maximize harvestable biomass.}, number={8}, journal={AGRONOMY-BASEL}, author={Linder, Eric R. and Young, Sierra and Li, Xu and Inoa, Shannon Henriquez and Suchoff, David H.}, year={2022}, month={Aug} }
 @article{suchoff_jackson_gunter_schultheis_louws_2021, title={Non-destructive characterization of grafted tomato root systems using the mini-horhizotron}, volume={1302}, ISSN={["2406-6168"]}, url={https://publons.com/wos-op/publon/56007334/}, DOI={10.17660/ActaHortic.2021.1302.28}, journal={II INTERNATIONAL SYMPOSIUM ON VEGETABLE GRAFTING}, author={Suchoff, D. H. and Jackson, B. E. and Gunter, C. C. and Schultheis, J. R. and Louws, F. J.}, year={2021}, pages={209–214} }
 @article{vann_suchoff_machacek_cheek_whitley_2021, title={Tobacco injury and sucker control efficacy following applications of pelargonic acid}, volume={7}, ISSN={["2374-3832"]}, url={https://doi.org/10.1002/cft2.20086}, DOI={10.1002/cft2.20086}, abstractNote={Core Ideas}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, publisher={Wiley}, author={Vann, Matthew C. and Suchoff, David H. and Machacek, Jeremy L. and Cheek, Joseph A. and Whitley, D. Scott}, year={2021} }
 @article{suchoff_schultheis_gunter_hassell_louws_2019, title={Effect of rootstock and nitrogen fertilizer on growth and yield in watermelon}, volume={94}, ISSN={["2380-4084"]}, url={http://dx.doi.org/10.1080/14620316.2019.1624629}, DOI={10.1080/14620316.2019.1624629}, abstractNote={ABSTRACT Herbaceous grafting can be used to manage numerous soilborne pathogens in cucurbits. Rootstocks have been reported to increase the growth of the scion possibly due to more efficient use of nitrogen compared with non-grafted plants. The first objective of this study was to determine if the commercial rootstocks ‘Strongtosa’, ‘Carnivor’, or ‘Macis’ improve growth and production of the watermelon ‘Melody’ scion. The second objective was to determine whether these rootstocks have different nitrogen requirements in open-field production compared with non-grafted ‘Melody’. Field studies were conducted in 2013 and 2014 on the Sandhills Research Station in Jackson Springs, North Carolina. Nitrogen fertiliser was applied via drip irrigation at 0, 84, 126, 168, and 252 kg⋅ha−1. A linear relationship between nitrogen rate and rootstock cultivar existed; however, in all cases the non-grafted plants produced more than all grafted plants. Average fruit weight from the non-grafted plants was also higher than the grafted plants. Fruit from ‘Carnivor’- and ‘Strongtosa’-grafted plants had higher flesh firmness compared with non-grafted ‘Melody’. Our findings suggest that rootstocks do not increase yield or growth in the scion nor do they require different nitrogen application rates. However, some rootstocks do improve overall fruit quality.}, number={6}, journal={JOURNAL OF HORTICULTURAL SCIENCE & BIOTECHNOLOGY}, author={Suchoff, David H. and Schultheis, Jonathan R. and Gunter, Christopher C. and Hassell, Richard L. and Louws, Frank J.}, year={2019}, month={Nov}, pages={798–804} }
 @misc{carr_cavigelli_darby_delate_eberly_gramig_heckman_mallory_reeve_silva_et al._2019, title={Nutrient Cycling in Organic Field Crops in Canada and the United States}, volume={111}, ISSN={["1435-0645"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85078252023&partnerID=MN8TOARS}, DOI={10.2134/agronj2019.04.0275}, abstractNote={Organic farmers have identified soil fertility and weed management as the two highest research priority areas. No review exists of research on soil nutrient management in organic field crop systems. We conducted a comprehensive review to identify the principles and factors governing nutrient management, knowledge gaps, and future research needs in organic grain and other field crop systems in Canada and the United States. We compared results from research conducted in different climates, soils, and crop rotational sequences. Results indicate that (i) dual‐use cover/green manure crops and/or animal manure are the most common sources of plant available N and other nutrients in organic field crop systems; (ii) soil nutrient deficiencies can develop through sole reliance on cover/green manure crops; (iii) dependence on animal manure can lead to N and P excesses; (iv) conventional soil testing procedures may not accurately predict crop nutrient needs; (v) greater knowledge of microbial processes governing nutrient cycling is needed; and (vi) better understanding of the impact of weeds on soil fertility may create weed and nutrient management synergies. Knowledge gaps include a lack in understanding of how the soil and plant biomes influence nutrient‐use efficiency and how crop diversity and rotations impact soil fertility, sustainability, and resilience in organic field crop systems. Likewise, interactions between weeds, crops, soil fertility, and weed management strategies are poorly understood.}, number={6}, journal={AGRONOMY JOURNAL}, author={Carr, Patrick M. and Cavigelli, Michel A. and Darby, Heather and Delate, Kathleen and Eberly, Jed O. and Gramig, Greta G. and Heckman, Joseph R. and Mallory, Ellen B. and Reeve, Jennifer R. and Silva, Erin M. and et al.}, year={2019}, pages={2769–2785} }
 @article{suchoff_gunter_schultheis_hassell_louws_2019, title={The effect of grafting on nitrogen use in determinate field-grown tomatoes}, volume={94}, ISSN={["2380-4084"]}, url={http://dx.doi.org/10.1080/14620316.2018.1450645}, DOI={10.1080/14620316.2018.1450645}, abstractNote={ABSTRACTGrafting tomato (Solanum lycopersicum L.) onto disease resistant rootstocks has grown in use in North America over the past two decades. Rootstocks have traditionally been bred and used for...}, number={1}, journal={JOURNAL OF HORTICULTURAL SCIENCE & BIOTECHNOLOGY}, author={Suchoff, David H. and Gunter, Christopher C. and Schultheis, Jonathan R. and Hassell, Richard L. and Louws, Frank J.}, year={2019}, month={Jan}, pages={102–109} }
 @article{suchoff_louws_gunter_2019, title={Yield and Disease Resistance for Three Bacterial Wilt-resistant Tomato Rootstocks}, volume={29}, ISSN={["1943-7714"]}, url={http://dx.doi.org/10.21273/horttech04318-19}, DOI={10.21273/HORTTECH04318-19}, abstractNote={Interest and use of grafted tomato (Solanum lycopersicum) in the United States continues to grow. Pioneered in Asia, herbaceous grafting is a commonly used cultural practice to manage many soilborne pathogens. Bacterial wilt (BW), caused by the pathogen Ralstonia solanacearum, is an aggressive soilborne pathogen that affects tomato grown in the southeastern United States. Traditional fumigation methods have limited effectiveness in the management of this pathogen. The present study was conducted to compare the bacterial wilt resistance of three commercially available tomato rootstocks, which are purported to be resistant to bacterial wilt: ‘Cheong Gang’, ‘RST-04-106-T’, and ‘Shield’. The determinate hybrid tomato ‘Red Mountain’, which is susceptible to bacterial wilt, was used as the scion and nongrafted control. Three locations were used over 2 years in North Carolina: an on-farm site with a history of bacterial wilt and two North Carolina Department of Agriculture Research Stations with no recent history of bacterial wilt. No disease symptoms were observed in any of the three grafted treatments, whereas the nongrafted controls showed between 30% and 80% disease incidence at the on-farm location. The resultant rootstock-imparted resistance improved marketable yields by between 88% and 125% compared with the nongrafted plants. When grown in locations lacking BW there were no yield benefits to grafting with any of the three rootstocks.}, number={3}, journal={HORTTECHNOLOGY}, publisher={American Society for Horticultural Science}, author={Suchoff, David H. and Louws, Frank J. and Gunter, Christopher C.}, year={2019}, month={Jun}, pages={330–337} }
 @article{bertucci_suchoff_jennings_monks_gunter_schultheis_louws_2018, title={Comparison of Root System Morphology of Cucurbit Rootstocks for Use in Watermelon Grafting}, volume={28}, ISSN={["1943-7714"]}, url={https://publons.com/wos-op/publon/39930266/}, DOI={10.21273/HORTTECH04098-18}, abstractNote={Grafting of watermelon (Citrullus lanatus) is an established production practice that provides resistance to soilborne diseases or tolerance to abiotic stresses. Watermelon may be grafted on several cucurbit species (interspecific grafting); however, little research exists to describe root systems of these diverse rootstocks. A greenhouse study was conducted to compare root system morphology of nine commercially available cucurbit rootstocks, representing four species: pumpkin (Cucurbita maxima), squash (Cucurbita pepo), bottle gourd (Lagenaria siceraria), and an interspecific hybrid squash (C. maxima × C. moschata). Rootstocks were grafted with a triploid watermelon scion (‘Exclamation’), and root systems were compared with nongrafted (NG) and self-grafted (SG) ‘Exclamation’. Plants were harvested destructively at 1, 2, and 3 weeks after transplant (WAT), and data were collected on scion dry weight, total root length (TRL), average root diameter, root surface area, root:shoot dry-weight ratio, root diameter class proportions, and specific root length. For all response variables, the main effect of rootstock and rootstock species was significant (P < 0.05). The main effect of harvest was significant (P < 0.05) for all response variables, with the exception of TRL proportion in diameter class 2. ‘Ferro’ rootstock produced the largest TRL and root surface area, with observed values 122% and 120% greater than the smallest root system (‘Exclamation’ SG), respectively. Among rootstock species, pumpkin produced the largest TRL and root surface area, with observed values 100% and 82% greater than those of watermelon, respectively. These results demonstrate that substantial differences exist during the initial 3 WAT in root system morphology of rootstocks and rootstock species available for watermelon grafting and that morphologic differences of root systems can be characterized using image analysis.}, number={5}, journal={HORTTECHNOLOGY}, publisher={American Society for Horticultural Science}, author={Bertucci, Matthew B. and Suchoff, David H. and Jennings, Katherine M. and Monks, David W. and Gunter, Christopher C. and Schultheis, Jonathan R. and Louws, Frank J.}, year={2018}, month={Oct}, pages={629–636} }
 @article{suchoff_perkins-veazie_sederoff_schultheis_kleinhenz_louws_gunter_2018, title={Grafting the Indeterminate Tomato Cultivar Moneymaker onto Multifort Rootstock Improves Cold Tolerance}, volume={53}, ISSN={["2327-9834"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85057832928&partnerID=MN8TOARS}, DOI={10.21273/HORTSCI13311-18}, abstractNote={Tomato (Solanum lycopersicum L.) is a warm-season, cold-sensitive crop that shows slower growth and development at temperatures below 18 °C. Improving suboptimal temperature tolerance would allow earlier planting of field-grown tomato and a reduction in energy inputs for heating greenhouses. Grafting tomato onto high-altitude Solanum habrochaites (S. Knapp and D.M. Spooner) accessions has proven effective at improving scion suboptimal temperature tolerance in limited experiments. This study was conducted to determine whether commercially available tomato rootstocks with differing parental backgrounds and root system morphologies can improve the tolerance of scion plants to suboptimal temperature. Two controlled environment growth chambers were used and maintained at either optimal (25 °C day/20 °C night) or suboptimal (15 °C day/15 °C night) temperatures. The cold-sensitive tomato cultivar Moneymaker was used as the nongrafted and self-grafted control as well as scion grafted on ‘Multifort’ (S. lycopersicum × S. habrochaites), ‘Shield’ (S. lycopersicum), and S. habrochaites LA1777 rootstocks. Plants were grown for 10 days in 3.8 L plastic containers filled with a mixture of calcined clay and sand. ‘Multifort’ rootstock significantly reduced the amount of cold-induced stress as observed by larger leaf area and higher levels of CO2 assimilation and photosystem II quantum efficiency. ‘Multifort’ had significantly longer roots, having 42% to 56% more fine root (diameter less than 0.5 mm) length compared with the other nongrafted and grafted treatments. Leaf starch concentration was significantly lower in ‘Multifort’-grafted plants at suboptimal temperatures compared with the self-grafted and nongrafted controls and the ‘Shield’-grafted plants at the same temperature. The ability for ‘Multifort’ to maintain root growth at suboptimal temperatures may improve root system sink strength, thereby promoting movement of photosynthate from leaf to root even under cold conditions. This work demonstrates that a commercially available rootstock can be used to improve suboptimal temperature tolerance in cold-sensitive ‘Moneymaker’ scions.}, number={11}, journal={HORTSCIENCE}, author={Suchoff, David H. and Perkins-Veazie, Penelope and Sederoff, Heike W. and Schultheis, Jonathan R. and Kleinhenz, Matthew D. and Louws, Frank J. and Gunter, Christopher C.}, year={2018}, month={Nov}, pages={1610–1617} }
 @article{louws_suchoff_kressin_panthee_driver_gunter_2018, title={Integrating grafting and emerging products to manage soilborne diseases of tomato}, volume={1207}, ISSN={0567-7572 2406-6168}, url={http://dx.doi.org/10.17660/actahortic.2018.1207.34}, DOI={10.17660/ActaHortic.2018.1207.34}, abstractNote={Major soilborne diseases in North Carolina and surrounding states include fusarium wilt (FW) (causal agent Fusarium oxysporum f. sp. lycopersici; all three races), verticillium wilt (VW) (Verticillium dahliae; two races), southern stem blight (SSB) (Sclerotium rolfsii), root-knot nematodes (RKN) (primarily Meloidogyne incognita) and bacterial wilt (BW) (Ralstonia solanacearum race 1), distributed across the subtropical to temperate ecosystems in the state. FW, VW, SSB, and RKN can be well managed using standard fumigants. Alternative management practices are needed in production systems where fumigants are not used or effective, and/or where heirloom tomato cultivars are grown. We are involved in a USA multi-state program to determine the viability of grafting in open-field production systems. Previously published work showed the utility of grafting to manage FW, SSB, RKN, and BW. In complementary work to manage BW, a replicated on-farm field trial demonstrates that fumigants such as Paladin (79% dimethyl disulfide + 21% chloropicrin) and PicClor60 (60% chloropicrin + 40% 1,3-dichloropropene) allow up to 80% plant death, similar to incidence in non-fumigated plots, whereas grafting to resistant rootstock (Seminis 'Cheong Gang') confers 100% control in non-fumigated plots. Another on-farm randomized complete block design experiment demonstrated that three commercially available rootstocks conferred 100% plant stand, whereas non-grafted plants had 80% plant death using a round tomato scion ('Red Mountain') or 15% plant death using a roma tomato ('Picus'). Grafted plants show economic viability in North Carolina, and additional work is needed to optimize this tool in diverse production systems.}, number={1207}, journal={Acta Horticulturae}, publisher={International Society for Horticultural Science (ISHS)}, author={Louws, F.J. and Suchoff, D. and Kressin, J. and Panthee, D. and Driver, J. and Gunter, C.}, year={2018}, month={Jul}, pages={249–254} }
 @article{suchoff_gunter_schultheis_kleinhenz_louws_2018, title={Rootstock Effect on Grafted Tomato Transplant Shoot and Root Responses to Drying Soils}, volume={53}, ISSN={["2327-9834"]}, url={https://publons.com/wos-op/publon/45897406/}, DOI={10.21273/HORTSCI13215-18}, abstractNote={Improvement of crop water use is imperative. Plants’ responses to limited water can dictate their ability to better use available resources and avoid prolonged and severe stress. The following study was conducted to determine how tomato (Solanum lycopersicum) rootstocks with different root system morphologies respond to drying soils. Plants were grown in pots containing an inorganic substrate composed of calcined clay and sand in a greenhouse on North Carolina State University’s campus. The heirloom tomato cultivar Cherokee Purple was used as the scion for ‘Beaufort’ and ‘Shield’ rootstocks as well as the self-grafted control. These rootstocks were assigned either normal or reduced irrigation treatments. Plants grown under the normal irrigation schedule were weighed and watered daily to maintain container capacity for one week. Those receiving reduced irrigation had all water withheld for one week, at which point strong midday wilting became evident. Shoot physiological and morphological data as well as root morphological data were collected at the end of the study. A constitutive positive increase on relative water content, leaf area, stomatal conductance (gS), and net CO2 assimilation rate was observed with scions grafted on ‘Beaufort’. In addition, this rootstock had a significantly longer total root system (118.6 m) compared with ‘Shield’ (94.9 m) and the self-grafted control (104.2 m). Furthermore, 76.4% of the total root length observed in ‘Beaufort’ was composed of very thin diameter roots ( <0.5 mm), which was higher than ‘Shield’ (73.67%) and the self-grafted control (69.07%). The only significant rootstock  irrigation interaction observed was for effective quantum yield of photosystem II (φPSII). At normal irrigation there were no differences among the rootstock treatments; however, at reduced irrigation ‘Beaufort’ had significantly higher φPSII than both ‘Shield’ and the self-grafted control. These results may explain some of the improved production and water use efficiency observed in field trials using ‘Beaufort’ rootstock, and data secured may allow for better screening of rootstocks for improved water use efficiency in the future.}, number={11}, journal={HORTSCIENCE}, publisher={American Society for Horticultural Science}, author={Suchoff, David H. and Gunter, Christopher C. and Schultheis, Jonathan R. and Kleinhenz, Matthew D. and Louws, Frank J.}, year={2018}, month={Nov}, pages={1586–1592} }
 @article{suchoff_schultheis_kleinhenz_louws_gunter_2018, title={Rootstock improves high-tunnel tomato water use efficiency}, volume={28}, ISSN={["1943-7714"]}, DOI={10.21273/HORTTECH03947-17}, abstractNote={Sphagnum peat is a finite resource that is often used in the horticultural industry as a component in many substrates, especially for greenhouse production of transplants. Because peatlands are being depleted by vast amounts of mining, the horticultural industry is exploring alternative resources to use in substrates. Swine lagoon sludge (SLS) is an attractive option as it may provide nutrients needed to support plant growth, as well as using an agricultural waste product to address the peat shortage. A compost was developed using an in-vessel compost reactor to compost SLS with peanut hulls [15:85 (by volume) SLS:peanut hull] to produce a swine lagoon compost (SLC). A greenhouse transplant study was conducted with three species: basil (Ocimum basilicum ‘Dark Opal’), chives (Allium schoenoprasum), and dill (Anethum graveolens ‘Hera’) grown in three substrates: SLC, a commercially available organic potting substrate with a nutrient charge (OM), and a commercial peat-based potting substrate with a 2-week nutrient charge (PEAT). The average height for basil, chives, and dill was significantly greater at transplant harvest when produced in the SLC substrate compared with the OM and PEAT. Airspace was greatest for SLC and lowest for OM and PEAT. Although root growth was not measured in this study, more prolific root growth throughout the plug was observed with SLC compared with OM and PEAT possibly because of the greater airspace in SLC. Substrate solution pH did not change substantially over time, whereas electrical conductivity (EC) decreased from 0.24 to 0.14 mS·cm−1. Both substrate pH and EC were within acceptable ranges for transplant production. SLC provided the physical and chemical requirements for herb transplant production without any additional fertilizers or amendments.}, number={3}, journal={HortTechnology}, author={Suchoff, D.H. and Schultheis, J.R. and Kleinhenz, M.D. and Louws, F.J. and Gunter, C.C.}, year={2018}, pages={337–343} }
 @article{suchoff_gunter_louws_2017, title={Comparative Analysis of Root System Morphology in Tomato Rootstocks}, volume={27}, ISSN={["1943-7714"]}, DOI={10.21273/horttech03654-17}, abstractNote={At its most basic, grafting is the replacement of one root system with another containing more desirable traits. Grafting of tomato (Solanum lycopersicum) onto disease-resistant rootstocks is an increasingly popular alternative for managing economically damaging soilborne diseases. Although certain rootstocks have demonstrated ancillary benefits in the form of improved tolerance to edaphic abiotic stress, the mechanisms behind the enhanced stress tolerance are not well understood. Specific traits within root system morphology (RSM), in both field crops and vegetables, can improve growth in conditions under abiotic stress. A greenhouse study was conducted to compare the RSM of 17 commercially available tomato rootstocks and one commercial field cultivar (Florida-47). Plants were grown in containers filled with a mixture of clay-based soil conditioner and pool filter sand (2:1 v/v) and harvested at 2, 3, or 4 weeks after emergence. At harvest, roots were cleaned, scanned, and analyzed with an image analysis system. Data collected included total root length (TRL), average root diameter, specific root length (SRL), and relative diameter class. The main effect of cultivar was significant (P ≤ 0.05) for all response variables and the main effect of harvest date was only significant (P ≤ 0.01) for TRL. ‘RST-106’ rootstock had the longest TRL, whereas ‘Beaufort’ had the shortest. ‘BHN-1088’ had the thickest average root diameter, which was 32% thicker than the thinnest, observed in ‘Beaufort’. SRL in ‘Beaufort’ was 60% larger than ‘BHN-1088’. This study demonstrated that gross differences exist in RSM of tomato rootstocks and that, when grown in a solid porous medium, these differences can be determined using an image analysis system.}, number={3}, journal={HORTTECHNOLOGY}, publisher={American Society for Horticultural Science}, author={Suchoff, David H. and Gunter, Christopher C. and Louws, Frank J.}, year={2017}, month={Jun}, pages={319–324} }
 @article{suchoff_gunter_louws_2017, title={Grafting research studies plant stress resilience}, volume={51}, journal={Vegetable Growers News}, author={Suchoff, D.H. and Gunter, C.C. and Louws, F.J.}, year={2017}, pages={11} }
 @misc{suchoff_gunter_schultheis_jackson_hassell_louws_2015, title={Characterization of Root Systems in Tomato and Tomato Rootstocks Through the Use of Mini-Horhizotron Technology}, author={Suchoff, D.H. and Gunter, C.C. and Schultheis, J.R. and Jackson, B.E. and Hassell, R.L. and Louws, F.J.}, year={2015}, month={Aug} }
 @misc{suchoff_gunter_schultheis_hassell_louws_jackson_2015, title={Response of Grafted Tomatoes to Nitrogen}, author={Suchoff, D.H. and Gunter, C.C. and Schultheis, J.R. and Hassell, R.L. and Louws, F.J. and Jackson, B.E.}, year={2015}, month={Aug} }
 @misc{suchoff_schultheis_gunter_hassell_louws_jackson_2015, title={Response of Grafted Watermelon to Nitrogen}, author={Suchoff, D.H. and Schultheis, J.R. and Gunter, C.C. and Hassell, R.L. and Louws, F.J. and Jackson, B.E.}, year={2015}, month={Jan} }
 @misc{suchoff_schultheis_gunter_hassell_louws_jackson_2015, title={Yield enhancement and nitrogen use efficiency in grafted watermelon: Fact or fiction}, author={Suchoff, D.H. and Schultheis, J.R. and Gunter, C.C. and Hassell, R.L. and Louws, F.J. and Jackson, B.E.}, year={2015}, month={Jan} }
 @article{suchoff_louws_gunter_schultheis_2014, title={2013 On-farm Grafted Tomato Trial to Manage Bacterial Wilt}, volume={1086}, ISSN={["0567-7572"]}, DOI={10.17660/actahortic.2015.1086.14}, abstractNote={Grossing over $33.7 million in annual sales, North Carolina ranks 7th in the US for the production of tomatoes (Solanum lycopersicum). A replicated on-farm trial was conducted in Rowan County, NC. On May 30th, 2013, 8.1 ha of two bacterial wilt (BW; R. solanacearum (race 1)) resistant rootstocks were planted. The objective of this trial was to evaluate disease susceptibility and production in fields with BW history. In addition, plant spacing and training systems were compared. Two experimental sites, one fumigated and one non-fumigated, were arranged in a randomized complete block design with four replications, each consisting of 91.4 m-rows in a commercial plasticulture system. Each row contained 13 10-plant treatment plots (2A—2A—3 Factorial + Control): two rootstocks (‘801’, ‘802’; Rijk Zwaan), two training systems (single-leader, double-leaders), three between-plant spacings (45.7, 61.0, and 76.2 cm) with ‘Mountain Fresh’ as the scion and a non-grafted ‘Mountain Fresh’ control spaced at 45.7 cm. Wilt incidence was collected during the two harvests. Fruit were harvested twice at 69 and 84 days after transplanting. Wilt incidence was lower in the non-fumigated field and no differences in yield between the grafted and non-grafted plants were observed. In the fumigated field, the main effect of grafting tended to increase yield. Both the main effect of training system and spacing significantly affected yield in the grafted treatments. BW incidence was significantly higher in the non-grafted treatment (29.08%) than ‘801’ and ‘802’ rootstocks (0.909 and 0.183%, respectively) (P<.0001). Single-leader grafted plants had 2.54% more BW incidence than double-leader plants (P=0.0007). Grafted tomatoes offered an alternative method to fumigation as a means to reduce BW loss and sustain marketable yield.}, number={1086}, journal={Acta Horticulturae (ISHS)}, publisher={International Society for Horticultural Science (ISHS)}, author={Suchoff, D.H. and Louws, F.J. and Gunter, C.C. and Schultheis, J.R.}, year={2014}, pages={119–127} }
 @misc{suchoff_schultheis_gunter_louws_2014, title={2013 On-farm Grafted Tomato Trial to Manage Bacterial Wilt}, author={Suchoff, D.H. and Schultheis, J.R. and Gunter, C.C. and Louws, F.J.}, year={2014}, month={Mar} }
 @misc{suchoff_schultheis_gunter_louws_2014, title={2013 On-farm Grafted Tomato Trial to Manage Bacterial Wilt}, author={Suchoff, D.H. and Schultheis, J.R. and Gunter, C.C. and Louws, F.J.}, year={2014}, month={May} }
 @misc{suchoff_schultheis_gunter_louws_2014, title={Grafted Tomatoes: A Sustainable Alternative to Soil Fumigation}, author={Suchoff, D.H. and Schultheis, J.R. and Gunter, C.C. and Louws, F.J.}, year={2014}, month={Oct} }
 @misc{suchoff_schultheis_gunter_louws_2013, title={2013 On-farm Grafted Tomato Trial to Manage Bacterial Wilt}, author={Suchoff, D.H. and Schultheis, J.R. and Gunter, C.C. and Louws, F.J.}, year={2013}, month={Oct} }
 @misc{suchoff_gunter, title={Comparative Analysis of Tomato Rootstock Root System Morphology}, author={Suchoff, D.H. and Gunter, C.C.} }
 @misc{suchoff_louws_schultheis_kleinhenz_gunter, title={Grafted Tomato Shoot and Root Responses to Drying Soils}, author={Suchoff, D.H. and Louws, F.J. and Schultheis, J.R. and Kleinhenz, M.D. and Gunter, C.C.} }
 @misc{suchoff_perkins-veazie_schultheis_sederoff_kleinhenz_louws_gunter, title={Improving Tomato Cold Tolerance through Grafting}, author={Suchoff, D.H. and Perkins-Veazie, P. and Schultheis, J.R. and Sederoff, H.W. and Kleinhenz, M.D. and Louws, F.J. and Gunter, C.C.} }
 @misc{suchoff_louws_schultheis_kleinhenz_gunter, title={Rootstock-imparted Water Use Efficiency in Grafted Heirloom Tomatoes}, author={Suchoff, D.H. and Louws, F.J. and Schultheis, J.R. and Kleinhenz, M.D. and Gunter, C.C.} }