@article{rivard_s. o'connell_peet_welker_louws_2012, title={Grafting Tomato to Manage Bacterial Wilt Caused by Ralstonia solanacearum in the Southeastern United States}, volume={96}, ISSN={["1943-7692"]}, DOI={10.1094/pdis-12-10-0877}, abstractNote={ Bacterial wilt, caused by Ralstonia solanacearum, can result in severe losses to tomato (Solanum lycopersicum) growers in the southeastern United States, and grafting with resistant rootstocks may be an effective strategy for managing this disease. However, R. solanacearum populations maintain considerable diversity, and little information is known regarding the efficacy of commercially available rootstocks to reduce bacterial wilt incidence and subsequent crop loss in the United States. In this study, tomato plants grafted onto ‘Dai Honmei’ and ‘RST-04-105-T’ rootstocks had significantly lower area under the disease progress curve (AUDPC) values compared with nongrafted plants (P < 0.05). Across three locations in North Carolina, final bacterial wilt incidence for non- and self-grafted plants was 82 ± 14 to 100%. In contrast, bacterial wilt incidence for the grafted plants was 0 to 65 ± 21%. Final bacterial wilt incidence of plants grafted with Dai Honmei rootstock was 0 and 13 ± 3% at two locations in western North Carolina but 50 ± 3% at a third site in eastern North Carolina. Similarly, grafting onto RST-04-105-T rootstock significantly reduced AUDPC values at two of the three locations (P < 0.05) compared with that of the nongrafted plants, but performed poorly at the third site. Total fruit yields were significantly increased by grafting onto resistant rootstocks at all three sites (P < 0.05). Regression analyses indicated that yield was significantly negatively correlated with bacterial wilt AUDPC values (R2 was 0.4048 to 0.8034), and the use of resistant rootstocks enabled economically viable tomato production in soils naturally infested with R. solanacearum. }, number={7}, journal={PLANT DISEASE}, publisher={Scientific Societies}, author={Rivard, C. L. and S. O'Connell and Peet, M. M. and Welker, R. M. and Louws, F. J.}, year={2012}, month={Jul}, pages={973–978} }
 @article{rivard_sydorovych_o'connell_peet_louws_2010, title={An Economic Analysis of Two Grafted Tomato Transplant Production Systems in the United States}, volume={20}, ISSN={["1943-7714"]}, DOI={10.21273/horttech.20.4.794}, abstractNote={The grafting of herbaceous vegetables is an emerging development in the United States. This report provides an estimate of the variable costs of grafting within U.S. tomato (Solanum lycopersicum) transplant production systems. Grafted and nongrafted plants were propagated at two commercial farming operations in Ivanhoe, NC (NC) and Strasburg, PA (PA) and the farm in NC produced certified organic transplants. Detailed economic production sequences were generated for each site, and grafted and nongrafted transplant production costs were $0.59 and $0.13 in NC, and $1.25 and $0.51 in PA, respectively. Direct costs associated with grafting (e.g., grafting labor, clips, chamber, etc.) accounted for 37% to 38% of the added cost of grafting, and grafting labor was 11.1% to 14.4% of the cost of grafted transplant production. Seed costs represented 52% and 33% of the added cost of grafting at the two sites, and indirect costs (e.g., soil, trays, and heating) accounted for 10% and 30% of the added cost of grafting. Our findings suggest that under current seed prices and with similar production practices, the feasibility of grafting in the United States is not disproportionately affected by domestic labor costs. Additionally, the economic models presented in this report identify the cost of production at various transplant stages, and provide a valuable tool for growers interested in grafted tomato transplant production and utilization.}, number={4}, journal={HORTTECHNOLOGY}, publisher={American Society for Horticultural Science}, author={Rivard, Cary L. and Sydorovych, Olha and O'Connell, Suzanne and Peet, Mary M. and Louws, Frank J.}, year={2010}, month={Aug}, pages={794–803} }
 @article{rivard_s. o'connell_peet_louws_2010, title={Grafting Tomato with Interspecific Rootstock to Manage Diseases Caused by Sclerotium rolfsii and Southern Root-Knot Nematode}, volume={94}, ISSN={["1943-7692"]}, DOI={10.1094/pdis-94-8-1015}, abstractNote={ Southern blight (Sclerotium rolfsii) and root-knot nematodes (Meloidogyne spp.) cause severe damage to fresh-market tomato (Solanum lycopersicum) throughout the southeastern United States. Grafting is an emerging technology in U.S. tomato production, and growers require information regarding the resistance characteristics conferred by rootstocks. In this study, southern blight (SB) and root-knot nematodes (RKN) were effectively managed using interspecific hybrid rootstocks. During 2007 and 2008, field trials were carried out at two locations that had soils naturally infested with S. rolfsii. At the end of the growing seasons, the mean SB incidence of nongrafted plants was 27 and 79% at the two sites. SB incidence among plants grafted onto rootstock cultivars Big Power (one location only), Beaufort, and Maxifort ranged from 0 to 5%, and area under the disease progress curve (AUDPC) values were lower than for nongrafted and self-grafted controls (P < 0.01). At one location, soils were naturally infested with RKN, and all three rootstocks reduced RKN AUDPC and RKN soil populations at first harvest (P < 0.01). Big Power was particularly effective at reducing RKN galling and RKN soil populations at final fruit harvest (P < 0.01). Fruit yield was higher when resistant rootstocks were utilized (P < 0.05), and in our study grafting was effective at maintaining crop productivity in soils infested with S. rolfsii and M. incognita. }, number={8}, journal={PLANT DISEASE}, publisher={Scientific Societies}, author={Rivard, C. L. and S. O'Connell and Peet, M. M. and Louws, F. J.}, year={2010}, month={Aug}, pages={1015–1021} }
 @misc{louws_rivard_kubota_2010, title={Grafting fruiting vegetables to manage soilborne pathogens, foliar pathogens, arthropods and weeds}, volume={127}, ISSN={["1879-1018"]}, DOI={10.1016/j.scienta.2010.09.023}, abstractNote={Grafting is an important integrated pest management strategy to manage soilborne pathogens and other pests of solanaceous and cucurbitaceous crops. Important diseases managed by grafting are caused by fungal pathogens such as Verticillium, Fusarium, Pyrenochaeta and Monosporascus; oomycete pathogens like Phytophthora; bacterial pathogens, particularly Ralstonia; root knot nematodes and several soil-borne virus pathogens. Rootstocks can include intraspecific selections that utilize specific major resistance genes and interspecific and intergeneric selections that exploit non-host resistance mechanisms or multigenic resistance. Rootstock selection has also been documented to impact foliar pests including pathogens, arthropods and viruses. Over-reliance on specific rootstocks in production systems has led to the emergence of new pathogens or shifts in the host specificity of the pathogen population, emphasizing the need for multi-tactic approaches to manage soilborne pathogens. One advantage and associated challenge of grafting is that rootstock selection for disease management is site specific depending on the presence, population structure and dynamics of the pathogen, as well as edaphic, environmental and anthropogenic factors. The use of grafting as an Integrated pest management tool to manage biotic stress will be most successful when carried out with increasing knowledge about the biology, diversity, and population dynamics of the pathogen or other pests and when complemented with sustainable farming system practices. This review highlights major uses of grafting to manage soilborne pathogens, provides some novel information on managing foliar or other soilborne pests (insects, mites, weeds) and offers discussion on future research and applications.}, number={2}, journal={SCIENTIA HORTICULTURAE}, publisher={Elsevier BV}, author={Louws, Frank J. and Rivard, Cary L. and Kubota, Chieri}, year={2010}, month={Dec}, pages={127–146} }
 @article{rivard_louws_2008, title={Grafting to Manage Soilborne Diseases in Heirloom Tomato Production}, volume={43}, ISSN={["2327-9834"]}, DOI={10.21273/hortsci.43.7.2104}, abstractNote={Organic heirloom tomato production is limited in the southeastern United States by foliar and soilborne diseases, thermal stress, and weathered soil structure. Heirloom cultivars command a premium market, but tolerance to disease and abiotic stress is often poor. Organic growers need research that supports the advantages of market niches afforded by heirloom tomatoes through the development of integrated systems to manage pests and reduce risks of associated crop losses or low yields. Two major soilborne diseases common in the southeast, bacterial wilt (caused by Ralstonia solanacearum) and fusarium wilt (caused by Fusarium oxysporum f.sp. lycopersici), were effectively managed using susceptible heirloom scions grafted onto resistant rootstock. In naturally infested soil, bacterial wilt incidence for nongrafted ‘German Johnson’ was 79% and 75% in 2005 and 2006, respectively. ‘German Johnson’ showed no symptoms of bacterial wilt in either year when grafted onto the resistant genotypes CRA 66 or Hawaii 7996. Fusarium wilt incidence was 46% and 50%, respectively, in nongrafted and self-grafted ‘German Johnson’ controls. When ‘Maxifort’ rootstock was grafted with ‘German Johnson’, no symptoms of fusarium wilt were seen, and plants with ‘Robusta’ rootstock had an intermediate level of disease (29%). An evaluation of commercially available rootstock was carried out in three separate experiments in diverse organic production systems to determine yield impacts with low disease pressure. ‘Maxifort’ rootstock significantly increased yield in one location (P = 0.05), but ‘Maxifort’ and ‘Robusta’ rootstock did not consistently impact yield at the other two locations. Grafting is an effective management tool for organic growers in the southeast United States to reduce risk of crop loss resulting from soilborne diseases and will be a valuable component in an integrated pest management program.}, number={7}, journal={HORTSCIENCE}, publisher={American Society for Horticultural Science}, author={Rivard, Cary L. and Louws, Frank J.}, year={2008}, month={Dec}, pages={2104–2111} }