Progress 09/01/22 to 08/31/23
Outputs
Target Audience:Primary audience of the project is the tomato producers in southern US. This includes tomato producers, packers, shippers, agronomists, crop consultants, farm managers, field workers, seed companies, and dealers; and broccoli storage and shipping/transport personnel and companies. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two post-doctoral researchers had opportunities to help set up the fields, collect samples, and/or analyze data. Dr. Benjamin Waldo, had the opportunity to conduct nematode sampling, compile, and help analyze the nematode count data for the 2021 field trial. Dr. Lesley Schumacher, helped prepare the field by inoculating the field with RKN the previous fall. Two graduate students and two undergraduate students were also trained as a part of this project. Professional development trainaings for the county extension agents were also conducted to disseminate the outcomes of these studies. How have the results been disseminated to communities of interest?The outcomes of the project were disseminated through various means including extension bulletins, extension talks at the county extension meetings, oral presentaions at various conferences and also through several peer-reviewed journal articles. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Field trials were conducted in Georgia and South Carolina. Tomato cultivar Roadster was used as the scion. Control treatments included non-grafted Roadster in all experiments and self-grafted Roadster in Georgia. In all experiments, all rootstocks significantly reduced incidence of southern blight and increased vigor ratings compared to control treatments (P≤ 0.007). The rootstocks Maxifort, White Star, and SisSynII, but not Diamond, significantly increased marketable weight (P≤ 0.02) and crop value (P < 0.05) compared to control treatments. In South Carolina only, because of greater yields than in Georgia, net returns with Maxifort and White Star were significantly greater than net return with non-grafted Roadster (P = 0.004). When the wholesale price for fresh market tomato is ≥$13/box, grafting may be an effective and economical management for southern blight.Co-PI Rutter at USDA ARS analyzed data from field trials looking at the effect of using the resistant Solanum sisymbriifoliumroot stocks to control root knot nematode (RKN) populations. At harvest, reductions in the mean number of RKN in plots planted with resistant tomato rootstocks compared to plots planted with self-grafted tomatoes was observed. Though these numerical differences did not reach the level of statistical significance, the numerical trends support results from previous research that these resistant rootstocks can be used to reduce RKN populations in the field. As a part of large field demonstration in grower's field, tomato scion (cv. Roadstar) grafted on Maxifort rootstock was evaluated for southern blight and southern bacterial wilt. Roadstar self-grafted on its on rootstock was used as a control. Each treatment comprised of four-replicates/field plot with a linear length of 50-ft. The field has a history of both diseases and hence, it was chosen as a trial site. The crop was managed for other diseases and pests according to the UGA Cooperative Extension recommendations. Southern bacterial wilt was not observed throughout the trial; however, southern blight appeared late in the season (couple of weeks before harvest). The disease incidence was scored and analyzed. Based on the assessment at harvest, southern blight incidence was significantly lower for tomato plots that had Maxifort as a rootstock compared with control. As the disease appeared late in the season we did not observe any significant difference in yield and quality between two treatments. This trial was a part of field demonstration that was attended by tomato growers and county extension agents. Co-PI Rutter at USDA ARS analyzed the nematode count data from field trials looking at the effect of using ASD with different carbon sources to manage RKN populations. Statistical differences in nematode counts between ASD treatments in field trial was observed. Reductions in the number of RKN and spiral nematodes in the soil depending on the carbon source used for ASD compared to no carbon source controls, with the differences in spiral nematode reaching the level of statistical significance was also observed. The addition of any carbon source reduced the mean number of nematodes compared to no carbon treatment, regardless of the anerobic status of the plot. The cotton seed meal carbon source produced the best overall suppression of both RKN and spiral nematode. These results support the use of ASD as a management tool for plant parasitic nematodes.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Identification of Four Populations of Meloidogyne incognita in Georgia, United States, Capable of Parasitizing Tomato-Bearing Mi-1.2 Gene
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Evaluation of summer and winter cover crops for variations in host suitability for Meloidogyne incognita, M. arenaria and M. javanica
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Identification, diversity, and distribution of Meloidogyne spp. in vegetable fields of South Georgia, USA
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Occurrence of the Root-Knot Nematode Meloidogyne haplanaria in Vegetable Fields of South Georgia, U.S.A.
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Identification and Virulence of Five Isolates of Root-Knot Nematode Meloidogyne floridensis on Vegetables
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Successional effects of cover cropping and deep tillage on suppression of plant?parasitic nematodes and soilborne fungal pathogens
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Grafting Tomato to Manage Southern Blight, Prevent Yield Loss, and Increase Crop Value
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Progress 09/01/19 to 08/29/23
Outputs
Target Audience:Primary audience of the project is the tomato producers in southern US. This includes tomato producers, packers, shippers, agronomists, crop consultants, farm managers, field workers, seed companies, and dealers; and broccoli storage and shipping/transport personnel and companies. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two post-doctoral researchers had opportunities to help set up the fields, collect samples, and/or analyze data. Dr. Benjamin Waldo, had the opportunity to conduct nematode sampling, compile, and help analyze the nematode count data for the 2021 field trial. Dr. Lesley Schumacher, helped prepare the field by inoculating the field with RKN the previous fall. Two graduate and two undergraduate students were trained as a part of this project. How have the results been disseminated to communities of interest?The outcomes of this project was disseminated through various means including peer-reviewed journal articles, extension publications, oral and poster presentations at various extension meetings and scientific conferences. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Field trials were conducted in Georgia and South Carolina. Tomato cultivar Roadster was used as the scion. Control treatments included non-grafted Roadster in all experiments and self-grafted Roadster in Georgia. In all experiments, all rootstocks significantly reduced incidence of southern blight and increased vigor ratings compared to control treatments (P≤ 0.007). The rootstocks Maxifort, White Star, and SisSynII, but not Diamond, significantly increased marketable weight (P≤ 0.02) and crop value (P < 0.05) compared to control treatments. In South Carolina only, because of greater yields than in Georgia, net returns with Maxifort and White Star were significantly greater than net return with non-grafted Roadster (P = 0.004). When the wholesale price for fresh market tomato is ≥$13/box, grafting may be an effective and economical management for southern blight.Co-PI Rutter at USDA ARS analyzed data from field trials looking at the effect of using the resistant Solanum sisymbriifoliumroot stocks to control root knot nematode (RKN) populations. At harvest, reductions in the mean number of RKN in plots planted with resistant tomato rootstocks compared to plots planted with self-grafted tomatoes was observed. Though these numerical differences did not reach the level of statistical significance, the numerical trends support results from previous research that these resistant rootstocks can be used to reduce RKN populations in the field. As a part of large field demonstration in grower's field, tomato scion (cv. Roadstar) grafted on Maxifort rootstock was evaluated for southern blight and southern bacterial wilt. Roadstar self-grafted on its on rootstock was used as a control. Each treatment comprised of four-replicates/field plot with a linear length of 50-ft. The field has a history of both diseases and hence, it was chosen as a trial site. The crop was managed for other diseases and pests according to the UGA Cooperative Extension recommendations. Southern bacterial wilt was not observed throughout the trial; however, southern blight appeared late in the season (couple of weeks before harvest). The disease incidence was scored and analyzed. Based on the assessment at harvest, southern blight incidence was significantly lower for tomato plots that had Maxifort as a rootstock compared with control. As the disease appeared late in the season we did not observe any significant difference in yield and quality between two treatments. This trial was a part of field demonstration that was attended by tomato growers and county extension agents. Co-PI Rutter at USDA ARS analyzed the nematode count data from field trials looking at the effect of using ASD with different carbon sources to manage RKN populations. Statistical differences in nematode counts between ASD treatments in field trial was observed. Reductions in the number of RKN and spiral nematodes in the soil depending on the carbon source used for ASD compared to no carbon source controls, with the differences in spiral nematode reaching the level of statistical significance was also observed. The addition of any carbon source reduced the mean number of nematodes compared to no carbon treatment, regardless of the anerobic status of the plot. The cotton seed meal carbon source produced the best overall suppression of both RKN and spiral nematode. These results support the use of ASD as a management tool for plant parasitic nematodes.
Publications
|
Progress 09/01/21 to 08/31/22
Outputs
Target Audience:Primary audience of the project is the tomato producers in southeastern US. This includes tomato producers, packers, shippers, agronomists, crop consultants, farm managers, field workers, seed companies, and dealers; and tomato storage and shipping/transport personnel and companies.Other targets for dissemination include the broader scientific community concerned with the weeds, nematodes and soil-borne pathogens.Targets also include postdocs, graduate students, and undergraduate students who receive training in microbiology, molecular genetics, genomics, and scientific communication. Changes/Problems:PD Hajihassani has moved to University of Florida and Co-PI Dutta will be a new PD on this project. Co-PI Zhang has moved from Clemson University and Dr. David Lamie will be our new economist to finish remaining economic analysis of the project. What opportunities for training and professional development has the project provided?Four graduate students, three undergraduate students, and research technicians were trained throughout the duration of the project. How have the results been disseminated to communities of interest? Previous PD Hajihassani presented the findings from this project at multiple county growers' meetings in Georgia. Also, the results from this work were shared with growers, Extension agents and specialists and other agricultural communities at the Southern Region Small Fruit Consortium and the Southeast Regional Fruit and Vegetable Conference in Savannah in January 2022. Dr. Hajihassani also published an industry article in AgNet Media titled "Grafting in Tomato: A Practical Tool for Root-Knot Nematode Control".This article reveals some of the results from this project and can be found via https://specialtycropindustry.com/grafting-in-tomato-a-practical-tool-for-root-knot-nematode-control/. Co-PI Cuttulle, Keinath, Wechter, Zhang disseminated the outcomes of this project in several satte, regional and national meetings. What do you plan to do during the next reporting period to accomplish the goals?We plan to conduct field demontration trials in 2023 Spring.
Impacts
What was accomplished under these goals?
A repeat field trial was conducted at the University of Georgia Horticulture Research Farm in Tifton, GA in the summer of 2021 to examine the effect of grafting tomato cv, Roadster on Solanum sisymbriifolium rootstock and self-grafting in control of root-knot nematode when treated with four non-fumigant nematicides (Fluensulfone, Flupyram, Oxamyl and Burkholderia spp. strain A396. A susceptible non-grafted tomato and a nematode-resistant cultivar Red Bounty were also included in the study for comparison. Plants were grown on raised beds covered with plastic mulch and recommended rates of nematicides were injected into beds using a single drip tape before (Fluensulfone) or at transplant. Roadster tomato grafted onto S. sisymbriifolium significantly reduced root galling index and nematode populations in the soil compared with the non-grafted and self-grafted tomatoes regardless of being treated or not treated with any of the nematicides. Gall index in the rootstock did not differ from the resistant tomato, regardless of whether it was treated on nontreated with any of the nematicides. Both the rootstock and the resistant tomato reduced the soil nematode populations compared to other treatments. Tomato weights of medium, large, and extra-large sizes were significantly greater on the rootstock than that of self-grafted and resistant tomatoes. These results support the data obtained in 2020 and suggest that S. sisymbriifolium rootstock can suppress southern root-knot nematode populations and minimize the damage to tomato crops. In a separate study, different rootstocks were evaluated for resistance against the southern blight disease caused by the fungus Athelia rolfsii. The trial was conducted at the University of Georgia Black shank Farm in Tifton, GA in the summer of 2021. The plots were artificially infested with the fungus before laying the plastic beds. All three S. sisymbriifolium rootstocks (SIS Syn II, White Star and Diamond) significantly reduce the incidence of southern blight compared to non-grafted and self-grafted tomatoes. There were differences in response to the fungal infection between the rootstocks. At 3, 6, 8, and 10 weeks after planting, the rootstocks had fewer dead plants than the self- and non-grafted tomatoes. There were some significant increases in tomato yields with grafted plants compared to non- and self-grafted tomato. Greenhouse and field studies were conducted to evaluate anaerobic soil disinfestation (ASD) with mustard (Brassica sp.) meal, molasses, and herbicide applications for yellow nutsedge (Cyperus esculentus) control in tomato (Solanum lycopersicum). The treatments in these studies included factorial of two carbon sources [mustard meal + molasses (MMM) or no carbon amendment], three herbicide treatments [halosulfuron applied preemergence (PRE), halosulfuron applied postemergence (POST), and no herbicide] and two polyfilm treatments (polyfilm cover or polyfilm uncover). In field trials two polyfilm cover treatments were punctured and nonpunctured. Soil treatments included molasses at 14,000 L·ha21 and mustard meal at 2100 kg·ha21 . Halosulfuron was applied at a rate of 1 oz/acre for PRE or POST applications. Greater anaerobic conditions were achieved in polyfilm cover treatments amended with MMM. In greenhouse and field trials, the most effective treatments for reducing yellow nutsedge populations were ASD with MMM or combined with halosulfuron application (PRE- or POST-ASD), which delivered significantly higher weed control than all other treatments tested or controls. In field trials, ASD with MMM caused plant growth stunting 14 d after transplantation (DAT); however, plants recovered, and stunting or injury was often not observed at 42 DAT. These studies demonstrated that ASD using MMM can be an effective strategy for reducing yellow nutsedge populations; however, the more research is needed to ensure crop safety while using ASD technology. Co-PI Zhang conducted an assessment ofeconomic impact of using grafting and ASD, independently and in conjunction, to determine the best combination in terms of yield and net returns for producers. This study drew from tomato (Solanum lycopersicum) field trials on a 0.5-acre plot at the Clemson Coastal Research and Education Center in Charleston, SC, where five grafting and three ASD treatments were used in combinations for comparisons. Each treatment combination was subjected to sealed (plastic mulch covering a plot punctured 5 weeks after applying ASD treatment) and unsealed (plastic mulch covering a plot punctured immediately after the application of ASD treatment) plot conditions during the ASD phase of plant bed preparation. Treatment combinations with cottonseed meal carbon-sourced ASD were unviable because of lower net returns compared with treatment combinations without anaerobic soil disinfestation in nearly every case. Grafting ('Roadster' self-grafted) combined with molasses and chicken manure carbon-sourced ASD under unsealed plot conditions was the most optimal treatment combination in the field trials with the greatest gains (net return per acre) to producers. The positive synergistic effects of combining these methods suggest that grafting and anaerobic soil disinfestation yield better results in conjunction than separately
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Hajihassani, A., Hamidi, N., Cutulle, M.A., and Keinath A.P. Evaluation of Solanum sisymbriifolium as a rootstock to control Meloidogyne incognita in tomato. 2021 APS Annual Meeting (Plant Health). August 2-6, Online.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Singh, G., Wechter, W. P., Farmaha, B., and Cuttulle, M. 2022. Integration of halosulfuron and anaerobic soil disinfestation for weed control in tomato. HortTechnology 32:401-414.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2021
Citation:
Namdi, C. 2021. Delivery, movement, and efficacy of namaticides for management of plant-parasitic nematodes in vegetables. MS Thesis
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Progress 09/01/20 to 08/31/21
Outputs
Target Audience:The target audience for this project is Extension agents and growers in Georgia and the neighboring states. However, the results will be used by extension specialists, county extension agents, crop consultants and professionals. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?A master'sstudent, Chinaza Nnamdi, was partially funded by theproject and worked on the nematicide field trail. The project provided opportunities to train 5 undergraduate students on nematology, horticulture, and plant pathology. A postdoc, Dr. Benjamin Waldo, had the opportunity to conduct nematode sampling, compile, and help analyze the nematode count data for this year's field trial. Another Postdoc, Dr. Lesley Schumacher, helped prepare the field by inoculating the field with RKN the previous fall. How have the results been disseminated to communities of interest?Dr. Hajihassani presented the results from the nematicide trialat five virtual county growers meetings in Georgia from January to March 2021. In addition, in collaboration with the Southern IPM Center, a webinar program for nematode management in vegetable crops was conducted on January 25, 2021, with five speakers from South Carolina, Florida, North Carolina, Michigan, and Georgia (Hajihassani). The webinar had 244 registrations and 138 people in attendance from 27 countries. The results from the nematicide trial were also presented at this webinar. Dr. Cutulle presented the results from the ASD field trial at the Northeastern Weed Science Society (Virtual) in January of 2021. These results were also presented at the pre-plant tomato and virtual pepper meeting (Feb. 2021). Finally, the field trial (2nd year) was a stop on the 2021 Clemson Vegetable field day tour. What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, on-farm trials will be conducted,data from the nematicide, ASD, and southern blight experiments will be analyzed, and threemanuscripts will be written and submitted to peer-reviewed journals.
Impacts
What was accomplished under these goals?
The field study on the efficacy of four nematicides, including Nimitz, Velum Prime, Vydate, and Majestene, on the grafted, self-grafted, and non-grafted (susceptible 'Roadster' and resistant 'Red Bounty' cultivars) tomato plants for the root-knot nematode (RKN) control was repeated in 2021 in Tifton, GA. Nematicides were applied through the drip irrigation system, utilizing one drip tape per plastic bed. The interaction between nematicide and grafting was significant only for root gall severity. The rootstock and Red Bounty reduced (P< 0.05) gall severity more than self-grafted and non-grafted Roadster; however, no difference in gall severity was observed between the rootstock and Red Bounty, regardless of which nematicide was used. A similar trend in the nematode population density in the soil was observed at harvest when both the rootstock and Red Bounty treatments had significantly lower nematode counts than the self-grafted and non-grafted plants. There was no difference in tomato fruit weights of the small, medium, large, and extra-large sizes among the rootstock, self-grafted, and non-grafted plants regardless of which nematicide was used. The results demonstrate that grafting onto highly resistant rootstocks is a practical management approach forproducing susceptible tomato cultivars in soils infested with RKN. In the 2021 southern blight trial in Charleston, SC, all three rootstocks tested (Maxifort, White Star, and SisSyn II) reduced the incidence of southern blight. Incidence in all grafted treatments was <8%, while the incidence in the two non-grafted cultivars, Roadster and BHN 602, was >30%. Rootstock cultivars did not differ from each other for incidence. The three grafted treatments and non-grafted BHN 602 yielded an average of 91% more pink and red fruit than non-grafted Roadster. In addition, the three grafted treatments had more extra-large fruit, 97%, than the two non-grafted treatments, 82%. The 2021 ASD field study in Charleston, SC, consisted of the same main plot treatments and rootstock treatments that were implemented in the 2020 field trial. Cooler temperatures and lower rainfall before and during the establishment of the 2021 ASD trial might have impacted the cumulative anaerobicity. However, similar trends were observed this year with regard to carbon amendment effects. Both carbon source and carbon amendment had a significant impact on cumulative anaerobic conditions. The treatment combination that resulted in the greatest time the plots were anaerobic conditions consisted of cotton seed meal that was sealed in the plots. The cumulative anaerobic conditions seemed to positively correlate with nutsedge control. The plots that had the least amount of yellow nutsedge consisted of the cotton seed amendment that was sealed, while the Chicken manure + molasses sealed plots also had good nutsedge control. The highest yielding rootstock appeared to be Maxifort, which produced significantly more extra-large red tomatoes when compared to the other rootstock treatments. Interestingly, the chicken manure + molasses resulted in the greatest yield of extra-large tomatoes when averaging across all rootstocks. This might be related to the fact that there were fewer bacterial wilt colonies in the plots that were treated with Chicken manure + Molasses plots. In the ASD field study, RKN was found in all of the planting beds in March, before the ASD treatment and planting. All nematode densities were lower at pre-plant and harvest time points compared to pre-treatment samples. At the post-ASD pre-plant timepoint, Cotton seed meal treated plots had the lowest RKN densities, but densities did not significantly differ between anaerobic and aerobic treated plots. At harvest, cotton seed meal treated plots still had the lowest RKN densities, with Sis Syn II grafted and non-grafted Roadster cultivars also showing lower RKN densities. Anaerobic plots in general also had lower RKN densities than aerobic plots at harvest. We plan to take an additional round of soil samples and quantify any RKN damage on the roots double-cropped squash at the end of harvest. Using the data from the 2020 ASD trial, the economic impact of using grafting and anaerobic soil disinfestation, independently and in conjunction was evaluated to determine the best combination in terms of yield and net returns for producers. This study drew from the tomato field trial conducted in Charleston, SC, where five grafting and three anaerobic soil disinfestation treatments were used in combinations for comparisons. Treatment combinations with cottonseed meal carbon-sourced anaerobic soil disinfestation were unviable because of lower net returns compared with treatment combinations without anaerobic soil disinfestation in nearly every case. Grafting ('Roadster' self-grafted) combined with molasses and chicken manure carbon-sourced anaerobic soil disinfestation under unsealed plot conditions was the most optimal treatment combination in the field trials with the greatest gains (net return per acre) to producers. The positive synergistic effects of combining these methods suggest that grafting and anaerobic soil disinfestation yield better results in conjunction than separately.
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2021
Citation:
Hajihassani, A, Hamidi,N.,Cutulle, M.A., and Keinath, A.P. 2021. Evaluation of Solanum sisymbriifolium as a rootstock to control Meloidogyne incognita in tomato. American Phytopathological Society Annual Meeting (Plant Health), Virtual meeting.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Donahoo, T., Zhang, L., Cutulle, M. and Hajihassani, A. Economic Analysis of grafting and anaerobic soil disinfestation for tomato production in South Carolina. HortTechnology, 31 (5) https://doi.org/10.21273/HORTTECH04858-21
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Progress 09/01/19 to 08/31/20
Outputs
Target Audience:
Nothing Reported
Changes/Problems:The technician hired from the proposal found another job, thus we had to pull core funded (Permanent Clemson University technicians to work the project). We are actively searching for another technician. What opportunities for training and professional development has the project provided?A post-doc (Dr. Lesley Schumacher) was able to assist in inoculation of a field with root-knot nematodes in preparation for next year's field trial at USDA United States Vegetable Lab, Charleston, SC. A Research Professional III (Negin Hamidi, MS) hired from the proposal and is currently working on the project at the University of Georgia. In addition, data was included in the MS thesis of an agricultural economics student at Clemson University. How have the results been disseminated to communities of interest?We plan on presenting the results at virtual meetings this winter at both research conferences and extension workshops or county grower meetings. What do you plan to do during the next reporting period to accomplish the goals?Repeat studies, finalize economics analysis prepare manuscripts and hopefully present studies at field days.
Impacts
What was accomplished under these goals?
A field trial was conducted at the University of Georgia Horticulture Research Farm in Tifton, GA from May to August 2020 to evaluate the efficacy of four non-fumigant nematicides (Nimitz, Velum Prime, Vydate and Majestene) on grafted, selfgrafted and non-grafted tomato for Meloidogyne incognita control. Tomato cultivar roadster grafted onto S. sisymbriifolium (SIS Syn II) rootstock reduced root galling index (P< 0.0001) compared with the non-grafted and selfgrafted tomatoes. Root galling index in the rootstock however did not differ from the root-knot resistant Red Bounty tomato, regardless of whether it was treated on nontreated with any of the nematicides. A similar trend in the root-knot nematode numbers per 100 cm3 of soil was observed and both SIS Syn II rootstock and red bounty had lower nematode counts than that of the self- and non-grafted tomato treatments. A mid- and end of season evaluations of stand counts showed fewer dead plants (P< 0.0001) in red bounty, self- and non-grafted tomatoes compared to the rootstock treatment. Wilted and dead plants at different growth stages showing white mycelial growth on the base of stem near soil level were due to naturally infection of Athelia rolfsii in the experiment site. At harvest, crop vigor was also greater (P< 0.0001) in the rootstock treatment compared with the other treatments. Yields of medium, large, and extra-large tomatoes grafted on the rootstock were greater (P< 0.0001) than that of self-grafted and red bounty treatments. We also conducted another trial at the UGA Black shank Research Farm in Tifton, GA, during the spring and summer of 2020 to examine the response of three S. sisymbriifolium rootstocks (SIS Syn II, White Star and Diamond) to infection with Athelia rolfsii. High disease pressure was provided by artificial inoculation of A. rolfsii into soil. Grafting tomato roadster on all three rootstocks had fewer than 12% of plants showing wilting symptoms. At 3, 6, 8, and 10 weeks after planting, all three rootstocks had fewer dead plants (P< 0.0001) compared to self- and non-grafted tomatoes. Tomato fruits of most common size harvested and will be used for yield evaluation. In 2021 experiments, an effective rootstock "Maxifort" against the southern blight disease will be included for comparison of these results. In June 2020, tomato plants in Charleston, SC had symptoms of Pythium stem and root rot. Pythium was isolated from each cultivar. Percentage of plants that were wilted, stunted, or dead ranged from 20 to 83% but did not differ by ASD treatment (P=0.1004). At the first and second rating dates, however, more plants were dead in ASD treatments amended with cottonseed meal than in the no-C control treatment (P< 0.0001). Across all ASD treatments, fewer grafted plants were diseased or dead than non-grafted plants (P< 0.0001). The two S. sisymbriifolium rootstocks had fewer diseased plants than Maxifort rootstock (P=0.0035). Mean colony-forming units of Pythium spp. were greater, 30.5 per g soil, in control ASD treatments than in all ASD treatments, mean of 5.6 (P< 0.0001). However, Pythium populations in ASD treatments did not differ from nontreated soil (mean of 9.1) (P=0.2941). Thus, the 6 weeks of flooding in the control ASD treatments without a C source increased Pythium, and the ASD treatments with a C source had no effect on Pythium. In 2021 experiments, a nontreated control without flooding should be included to verify this result. In addition, the dead plants in the cottonseed meal treatment likely were due to phytotoxicity, not Pythium. Only 7 of 900 plants had symptoms of southern blight and sclerotia of the pathogen (Athelia rolfsii). Both carbon sources reduced the number of viable sclerotia in soil compared to the no-carbon control (P≤0.0004). Unfortunately, root-knot nematodes were only detected in 10% of the experimental plots which was too few to make an accurate assessment of either the ASD or rootstock treatments. However, stubby-root nematodes (Trichodorus and Paratrichodorus spp.) were present in the majority of samples tested, and their numbers did show some response to the main ASD treatments. A field at the USVL was inoculated with root-knot nematodes (Meloidogyne incognita) in preparation for next year's ASD-Rootstock trial. Prior to transplanting, goosegrass (the main weed in the study) counts per meter squared were taken from the main field trial (Rootstock scion-ASD trial). Based on these data facilitation of ASD resulted in significant goosegrass control. Furthermore, it appeared that cotton seed meal had some sort of allelopathic effect on the weeds as there were approximately half as many goosegrass plants in the unsealed check. After 10 days of transplanting, rootstocks Maxifort, SIS Syn II, and scion roadster were observed sensitive to the cotton seedmeal treatments in both aerobic and anaerobic conditions, while a 100 percent success rate was observed in nongrafted roadster and White Star rootstock in all treatments. The treatment of cottonseed + Anaerobic resulted in the highest rate of tomato mortality in the sensitive cultivars. Yield of most common size and color harvested and will be used for yield evaluation. Currently we are conducting a cost-benefit analysis and will have that result next reporting period. Two repeat greenhouse trials were conducted at the CREC-USVL to examine ASD for the ability to reduce the population density of weeds. The factors of carbon source and plastic seal had a significant effect (P< 0.0001) on percent yellow nutsedge control in trial 1 and 2. In both trials, combining mustard meal/molasses and plastic covering with either halosulfuron application timing resulted in 98% or greater control of yellow nutsedge. Similar percent yellow nutsedge control was observed in the plastic + mustard meal/ molasses when compared to either of the halosulfuron treatments + plastic cover. The increased efficacy of plastic seal alone and plastic seal + mustard meal/molasses in trial 2 could be associated with day length in the greenhouse and subsequent temperature increase. Plastic significantly improved weed control in both trials; however, the effect was more profound in trial 2, which was subjected to higher greenhouse temperatures.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Hajihassani, A., Rutter, W.B., Shartz, T., Woldemeskel, M., Ali, M.E. and Hamidi, N. 2020. Characterization of resistance to major tropical root-knot nematodes in Solanum sisymbriifolium. Phytopathology, 110: 666-673. https://apsjournals.apsnet.org/doi/10.1094/PHYTO-10-19-0393-R
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