Pub Date : 2023-05-04DOI: 10.1094/php-01-23-0009-rs
David E. Perla, Z. Hayden, M. Hausbeck
Crown rot and fruit rot, caused by the oomycete Phytophthora capsici, limit yield and quality of hard squash grown for processing. In a two-year field study, we compared four Butternut types (Cucurbita moschata), two Delicious varietal Hubbard types (Cucurbita maxima), and six Kabocha types (C. maxima) for crown rot resistance, and fruit characteristics relevant to processing including mesocarp soluble solids, percent dry matter, and average fruit weight in 2019 and 2020. To evaluate crown rot, plants were inoculated in replicated field trials. The C. moschata cultivars ‘Dickinson’, ‘Buckskin’, ‘New England Cheddar’, and ‘Ultra Butternut’ had significantly less plant death for both years (<15%) than other cultivars. Significantly fewer 'Thunder' plants died in 2020 (59.6%) compared to the Kabocha cultivars 'Sweet Mama' (>94.2%), 'Delica' (>92.3%), and 'Sunshine' (>90.4%) and had a lower rAUDPC value (≤22.4) in both years. In non-inoculated field trials, mature fruits were assessed for fruit characteristics. Of the resistant C. moschata cultivars, only ‘Ultra Butternut’ exhibited similar °Brix than ‘NK 580’ in both years and had comparable or greater dry matter and fruit weight. Kabocha cultivars with moderate crown rot susceptibility (i.e., ‘Thunder’) exhibited higher °Brix and dry matter and smaller fruit weight compared to ‘NK 580’ each year. Integrated management programs can be advanced by selecting cultivars with crown rot resistance. Further evaluation of desirable yield and quality characteristics of the resistant cultivars could accelerate acceptance of these cultivars by growers and processors.
辣椒疫霉菌引起的冠腐病和果腐病限制了加工用硬南瓜的产量和质量。在一项为期两年的实地研究中，我们比较了四种Butternut类型（Cucurbita moschata）、两种美味品种Hubbard类型（Cuurbita maxima）和六种Kabocha类型（C.maxima。为了评估冠腐病，在重复的田间试验中接种植物。moschata品种“Dickinson”、“Buckskin”、“New England Cheddar”和“Ultra Butternut”的植物死亡率在两年内都显著降低（94.2%），“Delica”（>92.3%）和“Sunshine”（>90.4%），rAUDPC值在两年内均较低（≤22.4）。在未接种的田间试验中，对成熟果实的果实特性进行了评估。在抗性C.moschata品种中，只有“Ultra Butternut”在这两年中表现出与“NK 580”相似的°Brix，并且具有相当或更大的干物质和果实重量。与每年的“NK 580”相比，具有中等冠腐敏感性的Kabocha品种（即“Thunder”）表现出更高的白利糖度和干物质，以及更小的果实重量。可以通过选择具有抗冠腐病能力的品种来推进综合管理计划。进一步评估抗性品种的理想产量和质量特征可以加速种植者和加工商对这些品种的接受。
{"title":"Commercial Hard Squash Cultivars Exhibit Differences in Susceptibility to Phytophthora Crown Rot","authors":"David E. Perla, Z. Hayden, M. Hausbeck","doi":"10.1094/php-01-23-0009-rs","DOIUrl":"https://doi.org/10.1094/php-01-23-0009-rs","url":null,"abstract":"Crown rot and fruit rot, caused by the oomycete Phytophthora capsici, limit yield and quality of hard squash grown for processing. In a two-year field study, we compared four Butternut types (Cucurbita moschata), two Delicious varietal Hubbard types (Cucurbita maxima), and six Kabocha types (C. maxima) for crown rot resistance, and fruit characteristics relevant to processing including mesocarp soluble solids, percent dry matter, and average fruit weight in 2019 and 2020. To evaluate crown rot, plants were inoculated in replicated field trials. The C. moschata cultivars ‘Dickinson’, ‘Buckskin’, ‘New England Cheddar’, and ‘Ultra Butternut’ had significantly less plant death for both years (<15%) than other cultivars. Significantly fewer 'Thunder' plants died in 2020 (59.6%) compared to the Kabocha cultivars 'Sweet Mama' (>94.2%), 'Delica' (>92.3%), and 'Sunshine' (>90.4%) and had a lower rAUDPC value (≤22.4) in both years. In non-inoculated field trials, mature fruits were assessed for fruit characteristics. Of the resistant C. moschata cultivars, only ‘Ultra Butternut’ exhibited similar °Brix than ‘NK 580’ in both years and had comparable or greater dry matter and fruit weight. Kabocha cultivars with moderate crown rot susceptibility (i.e., ‘Thunder’) exhibited higher °Brix and dry matter and smaller fruit weight compared to ‘NK 580’ each year. Integrated management programs can be advanced by selecting cultivars with crown rot resistance. Further evaluation of desirable yield and quality characteristics of the resistant cultivars could accelerate acceptance of these cultivars by growers and processors.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46645307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-01DOI: 10.1094/php-02-23-0016-rp
S. Harper, T. Northfield, Louis R. Nottingham, T. DuPont, A. Thompson, Bernandita V. Sallato, Corina F. Serban, Madalyn K. Shires, A. Wright, Katlyn A. Catron, Adrian T. Marshall, C. Molnar, W. Cooper
Stone fruits are a multi-billion-dollar industry for the U.S. and Canada, one that has repeatedly suffered significant economic losses to outbreaks of the X-disease phytoplasma (Candidatus Phytoplasma pruni) over the last century. Orchards and entire production areas have been abandoned, with corresponding losses to growers, fruit packers, and consumers. The most recent outbreak, in the U.S. Pacific Northwest, caused an estimated $65 million (USD) in lost revenue between 2015 and 2020 and is only increasing in incidence. Already present across much of the continental U.S. and Canada, the phytoplasma has a broad host range beyond stone fruit and is transmitted by at least eight leafhopper species therefore stone fruit production in any state is at significant risk. This recovery plan was produced as part of the National Plant Disease Recovery System (NPDRS) and is intended to provide a review of pathogen biology, assess the status of critical recovery components, and identify disease management research, extension, and education needs.
{"title":"Recovery Plan for X-disease in Stonefruit Caused by Candidatus Phytoplasma pruni","authors":"S. Harper, T. Northfield, Louis R. Nottingham, T. DuPont, A. Thompson, Bernandita V. Sallato, Corina F. Serban, Madalyn K. Shires, A. Wright, Katlyn A. Catron, Adrian T. Marshall, C. Molnar, W. Cooper","doi":"10.1094/php-02-23-0016-rp","DOIUrl":"https://doi.org/10.1094/php-02-23-0016-rp","url":null,"abstract":"Stone fruits are a multi-billion-dollar industry for the U.S. and Canada, one that has repeatedly suffered significant economic losses to outbreaks of the X-disease phytoplasma (Candidatus Phytoplasma pruni) over the last century. Orchards and entire production areas have been abandoned, with corresponding losses to growers, fruit packers, and consumers. The most recent outbreak, in the U.S. Pacific Northwest, caused an estimated $65 million (USD) in lost revenue between 2015 and 2020 and is only increasing in incidence. Already present across much of the continental U.S. and Canada, the phytoplasma has a broad host range beyond stone fruit and is transmitted by at least eight leafhopper species therefore stone fruit production in any state is at significant risk. This recovery plan was produced as part of the National Plant Disease Recovery System (NPDRS) and is intended to provide a review of pathogen biology, assess the status of critical recovery components, and identify disease management research, extension, and education needs.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42545475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-26DOI: 10.1094/php-10-22-0113-br
Xiaojing Shi, G. Jung, H. Sang, Toshihiko Yamada
Dollar spot, caused by the newly renamed ascomycete fungus Clarireedia spp., contributes to the aesthetic and functional damage, and ultimate death of turfgrass. Fluazinam, a protective fungicide belonging to the 2,6-dinitroaniline chemical group has proven to be one of the most efficacious fungicide classes of managing a variety of turfgrass diseases, including dollar spot, due to its low risk for fungicide resistance as a broad-spectrum fungicide. Dollar spot isolates collected from six New England golf courses with suspicious resistance to multiple fungicide classes had shown reduced sensitivity to fluazinam using a mycelial growth inhibition assay. This is the first report of reduced sensitivity to fluazinam in dollar spot field isolates in the United States. Briefly, in-vitro sensitivity assays of a total of 22 isolates collected from 12 golf courses and UMass turf research facilities showed that reduced fluazinam sensitivity of isolates were detected on six golf courses collected since 2017, demonstrating that fungi with higher exposure to fluazinam tend to develop reduced sensitivity over time. To date, there is no reported field resistance of fluazinam in C. jacksonii. However, the findings highlight the need for ongoing monitoring of in vitro and field sensitivity to fluazinam in C. jacksonii, as well as emphasizing judicious use of fluazinam in managing dollar spot disease to delay the development of fungicide resistance.
{"title":"First report of in vitro insensitivity to fluazinam of Clarireedia jacksonii causing dollar spot of turfgrass on New England golf courses","authors":"Xiaojing Shi, G. Jung, H. Sang, Toshihiko Yamada","doi":"10.1094/php-10-22-0113-br","DOIUrl":"https://doi.org/10.1094/php-10-22-0113-br","url":null,"abstract":"Dollar spot, caused by the newly renamed ascomycete fungus Clarireedia spp., contributes to the aesthetic and functional damage, and ultimate death of turfgrass. Fluazinam, a protective fungicide belonging to the 2,6-dinitroaniline chemical group has proven to be one of the most efficacious fungicide classes of managing a variety of turfgrass diseases, including dollar spot, due to its low risk for fungicide resistance as a broad-spectrum fungicide. Dollar spot isolates collected from six New England golf courses with suspicious resistance to multiple fungicide classes had shown reduced sensitivity to fluazinam using a mycelial growth inhibition assay. This is the first report of reduced sensitivity to fluazinam in dollar spot field isolates in the United States. Briefly, in-vitro sensitivity assays of a total of 22 isolates collected from 12 golf courses and UMass turf research facilities showed that reduced fluazinam sensitivity of isolates were detected on six golf courses collected since 2017, demonstrating that fungi with higher exposure to fluazinam tend to develop reduced sensitivity over time. To date, there is no reported field resistance of fluazinam in C. jacksonii. However, the findings highlight the need for ongoing monitoring of in vitro and field sensitivity to fluazinam in C. jacksonii, as well as emphasizing judicious use of fluazinam in managing dollar spot disease to delay the development of fungicide resistance.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47953175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-25DOI: 10.1094/php-02-23-0018-rs
LeAnn Lux, Jessica M. Halvorson, Bryan Hansen, Scott M. Meyer, G. Shi, Zhaohui Liu, A. Friskop
Bacterial leaf streak (BLS) is one of the most significant foliar diseases affecting hard red spring wheat (HRSW) production in North Dakota (ND). The most effective management tool for BLS is the use of host resistance; however, adoption and availability of resistant cultivars is limited for HRSW producers. This has led to questions pertaining to the use of copper-based products to suppress BLS severity in HRSW production. Four field experiments were conducted from 2020 to 2022 in ND to evaluate the efficacy of copper sulfate pentahydrate (CSP) applied at the flag leaf stage on reducing BLS severity and protecting HRSW yield and test weight. Experiments were conducted in a randomized complete block design with a split-plot arrangement with four replications. Three treatments served as the main plots (non-inoculated, inoculated, and inoculated + CSP applied at flag leaf). Five HRSW cultivars varying in host resistance served as sub-plots. A high level of disease occurred across all experiments. A combined analysis suggested the use of CSP did not provide adequate BLS suppression and did not protect HRSW yield or test weight regardless of HRSW susceptibility. The lowest mean yield loss was associated with the moderately resistant cultivar Boost (9%) and the highest was associated with the susceptible cultivar SY Rockford (19%). Variability in yield loss values amongst cultivars suggests more research is needed to strengthen our understanding of BLS in HRSW.
{"title":"Effect of Copper Sulfate Pentahydrate and Cultivar Resistance on Reducing Bacterial Leaf Streak in Hard Red Spring Wheat in North Dakota","authors":"LeAnn Lux, Jessica M. Halvorson, Bryan Hansen, Scott M. Meyer, G. Shi, Zhaohui Liu, A. Friskop","doi":"10.1094/php-02-23-0018-rs","DOIUrl":"https://doi.org/10.1094/php-02-23-0018-rs","url":null,"abstract":"Bacterial leaf streak (BLS) is one of the most significant foliar diseases affecting hard red spring wheat (HRSW) production in North Dakota (ND). The most effective management tool for BLS is the use of host resistance; however, adoption and availability of resistant cultivars is limited for HRSW producers. This has led to questions pertaining to the use of copper-based products to suppress BLS severity in HRSW production. Four field experiments were conducted from 2020 to 2022 in ND to evaluate the efficacy of copper sulfate pentahydrate (CSP) applied at the flag leaf stage on reducing BLS severity and protecting HRSW yield and test weight. Experiments were conducted in a randomized complete block design with a split-plot arrangement with four replications. Three treatments served as the main plots (non-inoculated, inoculated, and inoculated + CSP applied at flag leaf). Five HRSW cultivars varying in host resistance served as sub-plots. A high level of disease occurred across all experiments. A combined analysis suggested the use of CSP did not provide adequate BLS suppression and did not protect HRSW yield or test weight regardless of HRSW susceptibility. The lowest mean yield loss was associated with the moderately resistant cultivar Boost (9%) and the highest was associated with the susceptible cultivar SY Rockford (19%). Variability in yield loss values amongst cultivars suggests more research is needed to strengthen our understanding of BLS in HRSW.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47409071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-15DOI: 10.1094/php-11-22-0121-br
K. A. Johnson, Chunxian Chen, C. Bock, P. Brannen
Phony peach disease (PPD), caused by Xylella fastidiosa (Xf) subspecies multiplex (Xfm), is an important disease of peach in the southeastern United States. Seed transmission of Xf has not been reported for PPD, and research published in 1933 indicated seedlings grown from seeds of PPD trees did not develop the disease. Recombinase polymerase amplification (RPA) is a relatively new and rapid molecular detection process that has been commercialized as AmplifyRP® XRT + for Xf. We utilized this test to determine whether the Xf bacterium could be detected in peach seeds collected from PPD-infected trees. Initially, 25 seeds and 25 excised embryos were individually tested for Xf using qPCR, and Xf was not detected. In a more extensive study, 300 individual seeds were tested for Xf using RPA, and all seed were again negative for Xf. Our studies provide no new evidence to support vertical transmission of Xf from Xf-infected peach trees to peach seeds. However, prior to concluding that vertical transmission does not occur, additional studies to observe and test seedlings produced from seed collected from PPD trees should be conducted.
{"title":"Recombinase polymerase amplification did not detect Xylella fastidiosa subsp. multiplex in peach seeds from phony peach disease trees","authors":"K. A. Johnson, Chunxian Chen, C. Bock, P. Brannen","doi":"10.1094/php-11-22-0121-br","DOIUrl":"https://doi.org/10.1094/php-11-22-0121-br","url":null,"abstract":"Phony peach disease (PPD), caused by Xylella fastidiosa (Xf) subspecies multiplex (Xfm), is an important disease of peach in the southeastern United States. Seed transmission of Xf has not been reported for PPD, and research published in 1933 indicated seedlings grown from seeds of PPD trees did not develop the disease. Recombinase polymerase amplification (RPA) is a relatively new and rapid molecular detection process that has been commercialized as AmplifyRP® XRT + for Xf. We utilized this test to determine whether the Xf bacterium could be detected in peach seeds collected from PPD-infected trees. Initially, 25 seeds and 25 excised embryos were individually tested for Xf using qPCR, and Xf was not detected. In a more extensive study, 300 individual seeds were tested for Xf using RPA, and all seed were again negative for Xf. Our studies provide no new evidence to support vertical transmission of Xf from Xf-infected peach trees to peach seeds. However, prior to concluding that vertical transmission does not occur, additional studies to observe and test seedlings produced from seed collected from PPD trees should be conducted.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44613998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-12DOI: 10.1094/php-01-23-0004-s
M. Munir, Kimberly Leonberger, K. Kesheimer, Marguerite Bolt, Marion E. Zuefle, E. Aronson, Magdalena Ricciardi, Craig M. Schluttenhofer, D. Joly, Henry S. Smith, Jacqueline Coburn, Jose Franco Da Cunha Leme Filho, S. Rondon, C. Smart, A. Collins, A. Garfinkel, N. Gauthier
Hemp and marijuana, both Cannabis sativa L., are revitalized crops to U.S. agricultural and horticultural industries. Hemp (Δ⁹-Tetrahydrocannabinol content <0.3%) was reintroduced in 2014 under a pilot research program and legalized in 2018. Hemp can now be grown in all 50 states. Marijuana (Δ⁹-THC content > 0.3%), though classified as a Schedule I narcotic by the U.S. Drug Enforcement Administration (DEA), is legal in 40 states and the District of Columbia for medical and/or recreational use. Although C. sativa is often promoted as a pest-free crop, multiple diseases and arthropod pests have been identified and confirmed in recent years. There are limited options for control of diseases and pests affecting hemp. A survey of diagnosticians, researchers, and industry leaders conducted in 2021-22 sought to determine the distribution and occurrence of 76 common diseases and pests on C. sativa across the U.S. A total of 148 responses were collected and grouped by U.S. region: Western, Great Plains, North Central, Northeastern, and Southern. Survey results suggest that while some pathogens and pests are widely distributed across the U.S., others occur more frequently in specific regions. This finding may indicate variations in economic importance by region. Results from this survey provide a foundation for regional and national prioritization of research and regulatory activities.
{"title":"Occurrence and Distribution of Common Diseases and Pests of US Cannabis: A Survey","authors":"M. Munir, Kimberly Leonberger, K. Kesheimer, Marguerite Bolt, Marion E. Zuefle, E. Aronson, Magdalena Ricciardi, Craig M. Schluttenhofer, D. Joly, Henry S. Smith, Jacqueline Coburn, Jose Franco Da Cunha Leme Filho, S. Rondon, C. Smart, A. Collins, A. Garfinkel, N. Gauthier","doi":"10.1094/php-01-23-0004-s","DOIUrl":"https://doi.org/10.1094/php-01-23-0004-s","url":null,"abstract":"Hemp and marijuana, both Cannabis sativa L., are revitalized crops to U.S. agricultural and horticultural industries. Hemp (Δ⁹-Tetrahydrocannabinol content <0.3%) was reintroduced in 2014 under a pilot research program and legalized in 2018. Hemp can now be grown in all 50 states. Marijuana (Δ⁹-THC content > 0.3%), though classified as a Schedule I narcotic by the U.S. Drug Enforcement Administration (DEA), is legal in 40 states and the District of Columbia for medical and/or recreational use. Although C. sativa is often promoted as a pest-free crop, multiple diseases and arthropod pests have been identified and confirmed in recent years. There are limited options for control of diseases and pests affecting hemp. A survey of diagnosticians, researchers, and industry leaders conducted in 2021-22 sought to determine the distribution and occurrence of 76 common diseases and pests on C. sativa across the U.S. A total of 148 responses were collected and grouped by U.S. region: Western, Great Plains, North Central, Northeastern, and Southern. Survey results suggest that while some pathogens and pests are widely distributed across the U.S., others occur more frequently in specific regions. This finding may indicate variations in economic importance by region. Results from this survey provide a foundation for regional and national prioritization of research and regulatory activities.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":"1 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61308787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-11DOI: 10.1094/php-01-23-0005-rs
The use of plasticulture systems, which consist of raised beds, plastic mulch, and drip irrigation for watermelon production, has increased in the Southern United States in recent decades. The root-knot nematode (RKN), Meloidogyne incognita, is a significant pathogen of watermelon production in plasticulture systems and can cause varying levels of yield loss depending on the nematode population density if not properly controlled. Few new non-fumigant nematicides (fluensulfone, fluazaindolizine, and fluopyram) have emerged in the last decade to help manage RKNs. A two-year field study was conducted to examine the impact of different rates, application timing (i.e., days before transplanting [DBT], at transplanting [AT], and days after transplanting [DAT]), and combination of these new nematicides and an older one (oxamyl) in control of RKN in watermelon cv. ‘Fascination’. The nematicide treatments, except for a single-time application of oxamyl in 2019 and 2020, significantly reduced root galling compared to the untreated check. Similarly, all treatments, except a single application of oxamyl in 2020, resulted in a lower soil population level of M. incognita than the untreated check. All nematicide treatments, except a single application of fluensulfone and a two-time application of fluopyram at a half-recommended rate, increased fruit yields when compared to the untreated check. Overall, the drip application of new chemistries, known as 3-F nematicides, shows to be a useful option for RKN management in watermelon. At planting application of fluazaindolizine or fluopyram and two-time applications of oxamyl based on the manufacturer's recommended rate show potential to prevent the crop loss.
{"title":"Effect of different rates, application timing, and combination of non-fumigant nematicides in control of Meloidogyne incognita in watermelon in plasticulture","authors":"","doi":"10.1094/php-01-23-0005-rs","DOIUrl":"https://doi.org/10.1094/php-01-23-0005-rs","url":null,"abstract":"The use of plasticulture systems, which consist of raised beds, plastic mulch, and drip irrigation for watermelon production, has increased in the Southern United States in recent decades. The root-knot nematode (RKN), Meloidogyne incognita, is a significant pathogen of watermelon production in plasticulture systems and can cause varying levels of yield loss depending on the nematode population density if not properly controlled. Few new non-fumigant nematicides (fluensulfone, fluazaindolizine, and fluopyram) have emerged in the last decade to help manage RKNs. A two-year field study was conducted to examine the impact of different rates, application timing (i.e., days before transplanting [DBT], at transplanting [AT], and days after transplanting [DAT]), and combination of these new nematicides and an older one (oxamyl) in control of RKN in watermelon cv. ‘Fascination’. The nematicide treatments, except for a single-time application of oxamyl in 2019 and 2020, significantly reduced root galling compared to the untreated check. Similarly, all treatments, except a single application of oxamyl in 2020, resulted in a lower soil population level of M. incognita than the untreated check. All nematicide treatments, except a single application of fluensulfone and a two-time application of fluopyram at a half-recommended rate, increased fruit yields when compared to the untreated check. Overall, the drip application of new chemistries, known as 3-F nematicides, shows to be a useful option for RKN management in watermelon. At planting application of fluazaindolizine or fluopyram and two-time applications of oxamyl based on the manufacturer's recommended rate show potential to prevent the crop loss.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47925608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-11DOI: 10.1094/php-12-22-0125-rs
Jill C. Check, A. Byrne, M. Singh, K. Steinke, William W. Widdicombe, M. Chilvers
Tar spot of corn, caused by the fungus Phyllachora maydis, is an economically important foliar disease recently reported in the U.S and Canada. Due to the recent introduction of Phyllachora maydis, the impacts of cultural management practices on disease development are still unknown. Separate field studies were conducted to determine effects of nitrogen (N) application rate and plant density on disease development. Field trials were conducted across six site years in Michigan with two corn hybrids of differing disease susceptibility. Relative area under the disease progress curve (rAUDPC) was used to compare disease development between N application rates and plant densities. Nitrogen application rate had no significant effect on disease at any location. Plant density and disease had a significant (P < 0.05) inverse relationship at five of six site years, with an average 41% decrease in rAUDPC for every 1000 plant per hectare increase. The economically optimal planting density ranged from 73 to 77 thousand plants per hectare for $150 to $300 USD per metric ton corn prices, demonstrating relatively low planting densities were more profitable despite greater disease. Therefore, other disease management practices including hybrid selection may be more effective at protecting yield than increasing plant density.
{"title":"Effects of nitrogen application rate and plant density on severity of tar spot of corn","authors":"Jill C. Check, A. Byrne, M. Singh, K. Steinke, William W. Widdicombe, M. Chilvers","doi":"10.1094/php-12-22-0125-rs","DOIUrl":"https://doi.org/10.1094/php-12-22-0125-rs","url":null,"abstract":"Tar spot of corn, caused by the fungus Phyllachora maydis, is an economically important foliar disease recently reported in the U.S and Canada. Due to the recent introduction of Phyllachora maydis, the impacts of cultural management practices on disease development are still unknown. Separate field studies were conducted to determine effects of nitrogen (N) application rate and plant density on disease development. Field trials were conducted across six site years in Michigan with two corn hybrids of differing disease susceptibility. Relative area under the disease progress curve (rAUDPC) was used to compare disease development between N application rates and plant densities. Nitrogen application rate had no significant effect on disease at any location. Plant density and disease had a significant (P < 0.05) inverse relationship at five of six site years, with an average 41% decrease in rAUDPC for every 1000 plant per hectare increase. The economically optimal planting density ranged from 73 to 77 thousand plants per hectare for $150 to $300 USD per metric ton corn prices, demonstrating relatively low planting densities were more profitable despite greater disease. Therefore, other disease management practices including hybrid selection may be more effective at protecting yield than increasing plant density.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48583684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-05DOI: 10.1094/php-01-23-0007-sc
A. Keinath
Fungicides are the most common and important management technique for cucurbit downy mildew. Fungicide efficacy against the causal agent, Pseudoperonospora cubensis, an obligate biotroph, has been monitored on potted cucumber seedlings exposed to natural inoculum. The objective of this study was to compare efficacy of nine fungicides on cucumber (Cucumis sativus) against Clade 2 of P. cubensis with their efficacy on butternut squash (Cucurbita moschata) and watermelon (Citrullus lanatus), hosts primarily infected by Clade 1. Bioassays were done in Charleston, SC, USA, with all three hosts in October 2019 and 2020 and with butternut squash in July 2018. Lack of efficacy, determined as relative disease severity not significantly different from the water control, typically ≥ 50%, was detected with cymoxanil (Curzate), azoxystrobin (Quadris), dimethomorph (Forum), mandipropamid (Revus), or propamocarb (Previcur Flex) more frequently in Clade 2 isolates (7 of 18 times) than in Clade 1 isolates (12 of 43 times). Cymoxanil, azoxystrobin, and dimethomorph were ineffective in over half of the bioassays on all hosts. Mandipropamid was ineffective only against Clade 2 in both cucumber assays, while propamocarb was ineffective only against Clade 1 in two of three and one of two bioassays on butternut squash and watermelon, respectively. In all seven bioassays ethaboxam (Elumin) was effective to moderately effective, and cyazofamid (Ranman), fluazinam (Omega), and fluopicolide (Presidio) were effective.
{"title":"Congruent and Differential Responses of Pseudoperonospora cubensis Clades 1 and 2 to Downy Mildew Fungicides","authors":"A. Keinath","doi":"10.1094/php-01-23-0007-sc","DOIUrl":"https://doi.org/10.1094/php-01-23-0007-sc","url":null,"abstract":"Fungicides are the most common and important management technique for cucurbit downy mildew. Fungicide efficacy against the causal agent, Pseudoperonospora cubensis, an obligate biotroph, has been monitored on potted cucumber seedlings exposed to natural inoculum. The objective of this study was to compare efficacy of nine fungicides on cucumber (Cucumis sativus) against Clade 2 of P. cubensis with their efficacy on butternut squash (Cucurbita moschata) and watermelon (Citrullus lanatus), hosts primarily infected by Clade 1. Bioassays were done in Charleston, SC, USA, with all three hosts in October 2019 and 2020 and with butternut squash in July 2018. Lack of efficacy, determined as relative disease severity not significantly different from the water control, typically ≥ 50%, was detected with cymoxanil (Curzate), azoxystrobin (Quadris), dimethomorph (Forum), mandipropamid (Revus), or propamocarb (Previcur Flex) more frequently in Clade 2 isolates (7 of 18 times) than in Clade 1 isolates (12 of 43 times). Cymoxanil, azoxystrobin, and dimethomorph were ineffective in over half of the bioassays on all hosts. Mandipropamid was ineffective only against Clade 2 in both cucumber assays, while propamocarb was ineffective only against Clade 1 in two of three and one of two bioassays on butternut squash and watermelon, respectively. In all seven bioassays ethaboxam (Elumin) was effective to moderately effective, and cyazofamid (Ranman), fluazinam (Omega), and fluopicolide (Presidio) were effective.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41887970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-05DOI: 10.1094/php-01-23-0011-rs
Fusarium graminearum Schwabe is an important fungus causing root rot of soybean (Glycine max L.) in the United States. In this study, 248 accessions (including the susceptible check, ‘Williams 82’) from the USDA germplasm collection (MG 0 to V) were screened with a single isolate of F. graminearum using the inoculum layer inoculation method in the greenhouse to identify resistant parental materials. Disease severity was evaluated 21 days post-inoculation on a 1-to-5 rating scale and expressed as relative treatment effects (RTE). Eight accessions (PI437949, PI438292, PI612761A, PI438094B, PI567301B, PI408309, PI361090, and P188788) had significantly lower RTE when compared to ‘Williams 82’ based on 95% confidence intervals. Further, the effect of maturity groups (MG) was assessed on disease severity, and accessions belonging to MG 0 or I had significantly greater RTE than cultivars belonging to MGs II to V based on 95% confidence intervals. A genome-wide association study analysis was conducted using 42,079 single nucleotide markers and six marker-trait associations were identified that may be novel sources of F. graminearum resistance. The identification of new resistant parental materials and MTAs associated with resistance to F. graminearum will be useful in breeding programs for developing resistant cultivars.
{"title":"Sources of resistance, effect of maturity groups and marker-trait associations associated with Fusarium graminearum causing root rot of soybean (Glycine max)","authors":"","doi":"10.1094/php-01-23-0011-rs","DOIUrl":"https://doi.org/10.1094/php-01-23-0011-rs","url":null,"abstract":"Fusarium graminearum Schwabe is an important fungus causing root rot of soybean (Glycine max L.) in the United States. In this study, 248 accessions (including the susceptible check, ‘Williams 82’) from the USDA germplasm collection (MG 0 to V) were screened with a single isolate of F. graminearum using the inoculum layer inoculation method in the greenhouse to identify resistant parental materials. Disease severity was evaluated 21 days post-inoculation on a 1-to-5 rating scale and expressed as relative treatment effects (RTE). Eight accessions (PI437949, PI438292, PI612761A, PI438094B, PI567301B, PI408309, PI361090, and P188788) had significantly lower RTE when compared to ‘Williams 82’ based on 95% confidence intervals. Further, the effect of maturity groups (MG) was assessed on disease severity, and accessions belonging to MG 0 or I had significantly greater RTE than cultivars belonging to MGs II to V based on 95% confidence intervals. A genome-wide association study analysis was conducted using 42,079 single nucleotide markers and six marker-trait associations were identified that may be novel sources of F. graminearum resistance. The identification of new resistant parental materials and MTAs associated with resistance to F. graminearum will be useful in breeding programs for developing resistant cultivars.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43784365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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