Progress 01/01/16 to 09/30/20
Outputs
Target Audience:This research is intended to provide farmers with effective new methods to more safely control plant-parasitic nematodes of small fruit crops and tobacco and with fewer potential risks to the environment. Plant breeders, extension agronomists, and county extension agents can also use the information generated when developing new, improved cultivars and when advising farmers. Results may also apply to producers of other agricultural commodities that face similar problems, particularly crop production in fields infested by plant-parasitic nematodes. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Virginia Cooperative Extension (VCE) In-Service training programs were conducted for extension agents in counties where tobacco is produced. Additional In-Service training opportunities were also offered on disease and nematode control for small fruit crops. Summer tobacco field days, hemp field tours and visits, and strawberry grower meetings and field walks also provided opportunities for training and professional development. How have the results been disseminated to communities of interest?Results have been disseminated through Virginia Cooperative Extension (VCE) In-Service training programs for extension agents in counties where tobacco is produced and via grower meetings and field days for small fruit and tobacco producers.Results are also disseminated through VCE literature such as the annually updated VCE Pest Management Guides for commercial small fruit and for Field Crops (including tobacco) and the VCE Flue-Cured Tobacco Production Guides. Nematode management recommendations were also updated for the web-based Southern Region Small Fruits Consortium Pest Management Guide. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Host Resistance: Annual field experiments evaluated resistance to a tobacco cyst nematode andMeloidogyne arenaria. Results are shared with seed companies, other land-grant universities, cooperative extension personnel, and growers to facilitate the development, release, and use of nematode resistant cultivars as part of an IPM strategy for nematode control in tobacco. The use of resistant cultivars with crop rotation is the most viable strategy to reduce soil fumigation and nematicide use in US tobacco production. Globodera tabacum solanacearum (TCN): TCN reproduction was compared among 17 to 21 flue-cured tobacco entries in 2018-2020 via field experiments conducted in naturally-infested fields at Virginia Tech's Southern Piedmont Agricultural Research and Extension Center (SPAREC). Each trial compared the reproduction of entries from a Regional Flue-Cured Tobacco Variety Evaluation Program with standard susceptible and resistant cultivars. Final TCN reproduction ratios were lower for RJR EX601 compared to standard susceptible cultivar K 326 in 2020 but were intermediate for the other 19 cultivars and entries in the 2020 trial. Plant vigor data did not appear to correlate with TCN soil data, but plant uniformity on 28 July was highest for RJR EX604, RJR EX601. Vigor ofTCN-resistant cultivar NC 196 on 28 July was significantly higher than for susceptible K 326. Meloidogyne arenaria: Root-knot resistance trials could not be conducted in 2020, but had been performed in a commercial flue-cured tobacco field in Mecklenburg County, Virginia in 2016-2019. These field experiments compared galling caused by M. arenaria among entries from the Flue-Cured Tobacco Regional Small Plot Test (RSP) with that on standard susceptible and widely grown flue-cured tobacco cultivars. These results should be very useful to plant breeders in advancing resistant breeding lines, and to growers for selecting cultivars most appropriate for the conditions in the fields on their farms. Doctoral student Noah Adamo conducted 11 greenhouse trials from 2017-2019 and two field tests in 2018 and 2019 to further investigate the efficacy of Rk1 and Rk2, alone and combined, against M. arenaria race 2. Mr. Adamo additionally advanced ~180 families of a cross (performed by Dr. Ramsey Lewis at NC State University) between standard susceptible cultivar Hicks with T15-1-1 (source of Rk2 gene) to the F5 generation. These seed could help establish mapping populations to conduct genetic analyses of the effect of Rk2 on root-knot nematode parasitism and reproduction, eventually clarifying the inheritance of resistance to root-knot nematode biotypes. Mr. Adamo also evaluated how resistance from Rk1 and Rk2 compared with that from Nicotiana repanda, and the relationship between parasitism by M. arenaria and alkaloid and reducing sugar content in flue-cured tobacco. "Stacking" Rk1 and Rk2 imparted greater resistance to M. arenaria race 2 than either gene alone, but an entry incorporating genes from N. repanda exhibited significantly greater resistance than the combination of Rk1 and Rk2 based on root galling, nematode egg masses, and total M. arenaria eggs produced. Alkaloid content of flue-cured tobacco did not appear to hinder or increase root-knot nematode parasitism under greenhouse or field conditions. However, parasitism by M. arenaria increased nicotine content in tobacco roots, while at the same time reducing translocation of nicotine to leaves. Conversely, root-knot nematode parasitism reduced reducing sugars in roots but did not significantly influence the reducing sugar content of tobacco leaves. Nematode Management Agent (NMA) Evaluation: • Root-Knot Nematodes: Field nematicide experiments were conducted from 2016-2019 on a flue-cured tobacco farm in Mecklenburg County, Virginia in a field naturally infested by Meloidogyne arenaria. Trials each year evaluated different fumigant, non-fumigant, and biological nematicides. Because some new non-fumigant nematicides can now be applied safely after transplanting, various combinations of fumigant and especially non-fumigant products were also tested. Specific treatments included new, reduced risk, non-fumigant nematicides such as Velum Prime, Nimitz, and Salibro. Nimitz and Velum Prime are now registered for use by tobacco growers. Both Nimitz and Velum Prime have the lowest EPS signal word ("Caution") versus the highest warning signal word "Danger" for soil fumigants. The active ingredient in Velum Prime is fluopyram (also marketed as the fungicides Luna Privilege, Luna Experience, Luna Sensation, and Luna Tranquility). Traditional fumigant and non-fumigant nematicides were also compared with bionematicides such as Majestene and experimental bionematicides such as MBI-601 ("Ennoble", a product based on the fungus, Muscodor albus), MBI-203, and MBI-306. Pre-treatment populations of Pratylenchus were observed in a minority of experimental units, as well as ectoparasitic species such as stunt and spiral nematodes. Nematicide application often (but now always) reduced time to flowering, an important factor in tobacco production. Soil fumigation was perhaps most consistently associated with reductions in time to flowering.In-furrow application of non-fumigant nematicides such as Velum Prime was also sometimes associated with significant reductions in time to flowering in 2019. • Tobacco Cyst Nematode (TCN - Globodera tabacum solanacearum): Field experiments were also conducted in 2016-2020 in order to identify improved products and/or improved product use methods and patterns for TCN management. From 19 to 28 fumigant, non-fumigant, and biological nematicide treatments were compared each year for their effects on TCN parasitism, reproduction, and associated crop losses. Experimental variability often resulted in large numerical treatment differences not being statistically significant. Annual differences in environmental conditions also contributed to experimental variability. These results will guide labeling and VCE recommendations for potential new NMAs for growers. Fewer pyriform TCN juveniles were found in tobacco roots in 2020 after biofumigation with BioSense followed by 3 applications of MBI-306. Plant vigor in 2020 was higher on 9 July after 2 applications of Velum Prime compared to the use of MBI-306 after biofumigation with BioSense. Early season plant vigor was often greater after application of soil fumigants compared to non-fumigants and biological nematicides. Soil fumigation with Telone II, with or without 1-2 applications of Velum Prime, and use of Velum Prime, significantly reduced time to flowering in 2020 compared to use of BioSense with or without Majestene or MBI-306. Cured leaf yield in 2020 was significantly greater when Velum Prime was applied twice compared to the use of 1,200 lb/A BioSense with or without MBI-306 and the untreated control. Although combinations of varying soil fumigants sometimes appeared to increase nematode control, these increases were rarely statistically significant, and may not have been numerically large enough to be economically attractive to growers.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Adamo, N., C.S. Johnson, T.D. Reed and J.D. Eisenback. 2020. Observations on the influence of root-knot nematode resistance genes RK1 and RK2 on reproduction of Meloidogyne arenaria on flue-cured tobacco. 49th Tobacco Workers Conference, Louisville, KY, January 19-23, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Adamo, N., C.S. Johnson, J.D. Eisenback, and T.D. Reed. 2020. Influence of Meloidogyne arenaria on nicotine accumulation in conventional and low-alkaloid flue-cured tobacco. Annual meeting of the American Phytopathological Society, August 3, 2020. Virtual.
- Type:
Theses/Dissertations
Status:
Under Review
Year Published:
2020
Citation:
Adamo, N. 2020. Reproduction of the root-knot nematode Meloidogyne arenaria on flue-cured tobacco possessing resistance genes Rk1 and/or Rk2 and the impact of root-knot nematode parasitism on the accumulation of nicotine in conventional and low-alkaloid flue-cured tobacco. PhD dissertation to be submitted December 2020
- Type:
Other
Status:
Awaiting Publication
Year Published:
2021
Citation:
Johnson, C.S., Pfeufer, E., Hansen, Z., and Thiessen L. (2020). 2021-2022. Burley and Dark Tobacco Production Guide (a cooperative effort of the University of Kentucky, University of Tennessee, Virginia Tech, and NC State University) (436-050). Disease Management. Virginia Cooperative Extension.
- Type:
Other
Status:
Awaiting Publication
Year Published:
2020
Citation:
Johnson, C.S. (2020). Virginia Pest Management Guide for Field Crops (456-016). Disease and Nematode Management: Tobacco. Virginia Cooperative Extension.
- Type:
Other
Status:
Awaiting Publication
Year Published:
2020
Citation:
Johnson, C.S. (2020). 2020 Flue-Cured Tobacco Production Guide: Disease Control (436-048). Virginia Cooperative Extension.
- Type:
Other
Status:
Published
Year Published:
2020
Citation:
Yoder, KS, and Johnson, C.S. (2020) Commercial Small Fruits: Nematodes. P.2-27 2-29. In:2020 Pest Management Guide for Horticultural and Forest Crops (456-017). Virginia Cooperative Extension.
- Type:
Other
Status:
Published
Year Published:
2020
Citation:
Melanson, R.A., Johnson, C.S., Schnabel, G., Ferguson, M.H., Desaeger, J., Burrack, H, Pfeiffer, P., Sia, A., Hale, F., and Brannen, P. (2020). 2020 Southeast Regional Strawberry Integrated Pest Management Guide for Plasticulture Production. Southern Region Small Fruit Consortium.
- Type:
Other
Status:
Published
Year Published:
2020
Citation:
Pfeiffer, DG, Johnson, C, Yoder, KS, and Bergh, JC. (2020). Commercial Small Fruits: Disease and Insects. P.2-1 2-25. In:2020 Pest Management Guide for Horticultural and Forest Crops (456-017). Virginia Cooperative Extension.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Johnson, C.S., N. Adamo, S. Irby, and T.D. Reed. 2020. Efficacy of non-fumigant and/or fumigant products for tobacco nematode management in Virginia. 49th Tobacco Workers Conference, Louisville, KY, January 19-23, 2020.
- Type:
Other
Status:
Published
Year Published:
2020
Citation:
Johnson, C.S., and Robert S. Irby. 2020. Evaluation of nematicides for tobacco cyst nematode management in Virginia flue-cured tobacco, 2019. Plant Disease Management Reports 14:CF019.
- Type:
Other
Status:
Published
Year Published:
2020
Citation:
Johnson, C.S., T.D. Reed, and C.T. Clarke. 2020. Evaluation of nematicides for root-knot nematode management in Virginia flue-cured tobacco, 2019. Plant Disease Management Reports 14:N005.
|
Progress 10/01/18 to 09/30/19
Outputs
Target Audience:This research is intendedto provide farmers with effective new methods to control plant-parasitic nematodes of small fruit crops and tobacco, more safely, with fewer potential risks to the environment. Plant breeders, extension agronomists and county extension agents can also use the information generated when developing new, improved cultivars and when advising farmers. Results may also apply to producers of other agricultural commodities that face similar problems, particularly crop production in fields infested by plant-parasitic nematodes. Changes/Problems:Significant black shank occurred at our on-farm root-knot nematode test site for the first time in 2019, despite transplant water use of an effective oomycete fungicide. Additional black shank control steps need,and will be,taken in the future to preserve plant stands. What opportunities for training and professional development has the project provided?Virginia Cooperative Extension (VCE) In-Service training programs were conductedfor extension agents in counties where tobacco is produced. Summer tobacco field days, hemp field tours and visits, and strawberry grower meetings and field walks also provided opportunities for training and professional development. How have the results been disseminated to communities of interest?Results have been disseminated through a Virginia Cooperative Extension (VCE) In-Service training program for extension agents in counties where tobacco is produced and via grower meetings and field days for small fruit and tobacco producers. Results are also disseminated through VCE literature such as the annually updated VCE Pest Management Guides for commercial small fruit and for Field Crops (including tobacco) andthe 2019 VCE Flue-Cured Tobacco Production Guide. Nematode management recommendations were also updated for the web-based Southern Region Small Fruits Consortium Pest Management Guide. What do you plan to do during the next reporting period to accomplish the goals?I plan on continuing to conduct field trials, evaluating tobacco germplasm for resistance to Meloidogyne arenaria, and to Globodera tabacum solanacearum. Field research will also be conducted to compare potential new nematicide and bionematicide products for their ability to limit root-knot and tobacco cyst nematode parasitism and reproduction and the resulting crop damage. My graduate student will continue his research to clarify the mechanisms involved in tobacco resistance to M. arenaria and on the relationship between parasitism by M. arenaria and alkaloid (nicotine) production in parasitized plant tissues.
Impacts
What was accomplished under these goals?
Host Resistance: Globodera tabacum solanacearum (TCN):TCN reproduction was compared among 17 flue-cured tobacco entries transplanted into a naturally infected field at Virginia Tech's Southern Piedmont Agricultural Research and Extension Center (SPAREC). Although standard TCN-susceptible and TCN-resistant cultivars were included in the experiment, no significant differences were noted in the number of TCN eggs/500cm3 of soil at the end of the growing season, even when adjusted for estimated initial TCN populations, among any entries in the trial. In fact, mean final TCN populations were similar or lower compared to those collected in May for all entries in the study. Meloidogyne arenaria:A 2019 field experiment compared galling caused by M. arenaria among seven entries from the Flue-Cured Tobacco Regional Small Plot Test (RSP) with that on standard susceptible (and widely grown) flue-cured tobacco cultivar NC 196. Differences in mean root galling on 3 October were not statistically significant, although mean root galling among RSP entries ranged from 5% to 37% versus 56% on NC 196. A 28-day greenhouse pot trial and an additional 45-day trial were also conducted in 2019 by graduate student Noah Adamo to assess the ability of M. arenariato penetrate and reproduce on a panel of tobacco entries encompassing a range of resistance genotypes, including a susceptible entry, entries homozygous for one of two root-knot nematode resistance genes (RK1orRK2), and entries carrying one or two copies of both genes. Low alkaloid entries were also included in the experiment in order to evaluate the impact of RKN feeding on the accumulation of nicotine and other alkaloids in leaf tissue and to preliminarily evaluate RKN resistance traits in as yet unreleased entries. Preliminary analyses indicate that root knot nematode parasitism increased the content of total alkaloids in root, but not leaf tissue, 28 days after inoculation. A subset of the same entries was also planted in a commercial tobacco field with a history ofM. arenariapressure. Entrieswere evaluated throughout the growing season for above ground vigor and uniformity, root weight and health, as well as galling and penetration by juvenile nematodes and subsequent life stage development. Additional metrics including numbers of egg masses and numbers of eggs will be calculated from a representative subsample in cases where egg masses are observed in preliminary observations.These data will be correlated with total alkaloid data from roots and leaves to further quantify the impact of RKN feeding behavior on alkaloid synthesis and translocation. Nematode Management Agent (NMA) Evaluation: Root-Knot Nematodes: A 2019 field experiment evaluated 17 different fumigant, non-fumigant, and biological nematicides for their control of Meloidogyne arenaria in a commercial tobacco field in Mecklenburg County, Virginia. No significant differences were noted among treatments in subjective ratings of plant vigor and uniformity made on 2 July or 20 August. However, 70% of plants were in the flowering stage on 20 August where 7 fl oz/A of Velum Prime (fluopyram) was applied in the furrow just before transplanting, in soil previously fumigated at bedding with 5 gal/A of Telone II (1,3-dichloropropene). Flowering on that date was 43% or lower for all other treatments in the trial, although flowering tended to be higher for treatments including the 5 gal/A Telone II application. Flowering within untreated control plots averaged 10%. Flowering was also relatively higher for MBI-203, a new formulation of a bionematicide, and was significantly higher than that for a transplant water application of Velum Prime (fluopyram). Percent galling on 3 October ranged from 55% to 0.3% among experimental treatments, with galling of 3% or lower for 12 of 17 treatments. However, reduced galling was statistically significant only for three treatments (51 fl oz/A Salibro, 9 pt/A Nimitz, and 21 fl oz/A Velum Prime) compared to the untreated control. Although estimated yields ranged from 2,447 to 4,226 lb/A, apparent trends among treatments were not statistically significant. Tobacco Cyst Nematode (TCN - Globodera tabacum solanacearum): A 2019 field experiment evaluated the effects of 19 fumigant, non-fumigant, and biological nematicide treatments on TCN parasitism, reproduction, and associated crop losses. TCN juveniles and adults in roots on 17 Jul tended to be much (and significantly) lower where a non-fumigant nematicide was applied near transplanting to soil that had already been fumigated with 9 gal/A of Telone II. The percentage of plants topped on 13 August also tended to be higher for treatments combining soil fumigation with transplant use of a non-fumigant nematicide. Although final cured leaf yields varied by 38% compared to the lowest yielding treatment, apparent differences were not statistically significant. Still, treatments following soil fumigation with application of a non-fumigant product at transplanting were numerically among the highest yielding treatments. Yields associated with use of Majestene or MBI 306 were either within 100 lb/A or below that of the untreated control.
Publications
- Type:
Other
Status:
Published
Year Published:
2019
Citation:
Johnson, C.S., T.D. Reed, and C.T. Clarke. 2019. Evaluation of nematicides for root-knot management in Virginia flue-cured tobacco, 2018. Plant Disease Management Reports 13:N017.
- Type:
Other
Status:
Other
Year Published:
2019
Citation:
Johnson, C.S., T.D. Reed, and C.T. Clarke. 2019. Resistance to root-knot nematode in flue-cured tobacco cultivars in Virginia, 2018. Plant Disease Management Reports 13:N018.
- Type:
Other
Status:
Other
Year Published:
2019
Citation:
Johnson, C.S. 2019. Tobacco cyst nematode resistance in flue-cured tobacco cultivars in Virginia, 2018. Plant Disease Management Reports 13:N019.
- Type:
Other
Status:
Published
Year Published:
2019
Citation:
Johnson, C.S., T.D. Reed, and C.T. Clarke. 2019. Evaluation of nematicides for root-knot management in Virginia flue-cured tobacco, 2017. Plant Disease Management Reports 13:N020.
- Type:
Other
Status:
Submitted
Year Published:
2019
Citation:
Johnson, C.S., and Robert S. Irby. 2020. Evaluation of nematicides for tobacco cyst nematode management in Virginia flue-cured tobacco, 2019. Plant Disease Management Reports 14:
- Type:
Theses/Dissertations
Status:
Submitted
Year Published:
2019
Citation:
Johnson, C.S., T.D. Reed, and C.T. Clarke. 2020. Evaluation of nematicides for root-knot nematode management in Virginia flue-cured tobacco, 2019. Plant Disease Management Reports 14:
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Adamo, N., C.S. Johnson, and J.D. Eisenback. 2019. Proficiency of individual or paired root-knot nematode juveniles in locating and penetrating susceptible plant roots. Annual meeting of the Society of Nematologists, July 7-10, 2019. Raleigh, NC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Johnson, C.S., N. Adamo, and R.S. Irby. 2019. Comparisons of fluopyram and fluensulfone to manage Globodera tabacum solanacearum on tobacco in Virginia. Annual meeting of the Society of Nematologists, July 7-10, 2019. Raleigh, NC.
|
Progress 10/01/17 to 09/30/18
Outputs
Target Audience:This research is intended to provide farmers with effective new methods to control plant-parasitic nematodes of cultivatedtobacco more safely with fewer potential risks to the environment. Plant breeders,extension agronomists and county extension agents can also use the information generated when developing new, improved cultivars and when advising farmers. Results may also apply to producers of other agricultural commodities that face similar problems, particularly crop production in fields infested by plantparasitic nematodes. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Results have been disseminated through a Virginia Cooperative Extension (VCE) In-Service training program for extension agents in counties where tobacco is produced and via grower meetings for small fruit and tobacco producers, as well as the 2018 Southeastern Strawberry Expo. Results are also disseminated through extension literature such as the annually updated VCE Pest Management Guides for commercial small fruit and for Field Crops (including tobacco) andthe VCE Flue-Cured Tobacco Production Guide. Nematode management recommendations were also updated for the web-based Southern Region Small Fruits Consortium Pest Management Guide. How have the results been disseminated to communities of interest?Results have been disseminated through a Virginia Cooperative Extension (VCE) In-Service training program for extension agents in counties where tobacco is produced and via grower meetings for small fruit and tobacco producers, as well as the 2018 Southeastern Strawberry Expo. Results are also disseminated through extension literature such as the annually updated VCE Pest Management Guides for commercial small fruit and for Field Crops (including tobacco) andthe VCE Flue-Cured Tobacco Production Guide. Nematode management recommendations were also updated for the web-based Southern Region Small Fruits Consortium Pest Management Guide. What do you plan to do during the next reporting period to accomplish the goals?I plan to continue field trials evaluating tobacco germplasm for resistance toMeloidogyne arenariaand toGlobodera tabacum solanacearum. Field research will also be conducted to compare potential new nematicide and bionematicide products for their ability to limit root-knot and tobacco cyst nematode parasitism and reproduction and the resulting crop damage. My graduate student will continue his greenhouse and field research to clarify the mechanism(s) involved in tobacco resistance toM. arenaria.
Impacts
What was accomplished under these goals?
Host Resistance: Twenty-one entries of flue-cured tobacco were evaluated for resistance to TCN (tobacco cyst nematode,Globodera tabacum solanacearum) in a 2018 field experiment. While TCN populations increased on all entries between May and October, increases were significantly lower on cultivars PVH 1600 and PVH 2310 (both possessing thePhpgene) compared to standard susceptible cultivars K 326 and Hicks, as well as GF 318 and PVH 2254. Final season TCN populations were intermediate between these two extremes for the majority of the other entries in the study. Unexpected results were noted for some entries (CC 1063, GL 26H, GF 318), and possible explanations for these results are currently being investigated. Six breeding lines were compared to one commercial cultivar for resistance to root-knot nematode, primarilyMeloidogyne arenaria. Percent galling on 10 October was significantly lower on breeding lines PXH 10 and NC EXT 89 versus NC 196, which possesses onlyRk1(conferring resistance to races 1 and 3 ofM. incognita). PXH 10 and NC EXT 89 likely possessRk1, but it is currently not known whether or not either also possessesRk2, thought to confer partial resistance toM. arenaria. We completed 3, 28-day greenhouse pot trials in 2018 to assessthe ability of a population ofM. arenariato penetrate and reproduce on 5 different tobacco entries. Therange of resistance genotypes includeda susceptible entry, entries homozygous for one of two root-knot nematode resistance genes (RK1/RK2), and entries carrying one or two copies of both genes. The same entries were planted in three different tobacco fields this past growing season that had a history ofM. arenariapressure. Above ground vigor and uniformity and root weight and health were evaluated throughout the growing season, as well as root-knot specific metrics that included galling and penetration by juvenile nematodes and subsequent life stage development (still in progress). Additional metrics that include the number of egg masses and number of eggs will be calculated from a representative sub-sample in cases where egg masses are observed in preliminary observations.Although galling byM. arenariawas significantly suppressed by tobacco genotypes with bothRk1andRk2in the field study, this trend wasn't apparent in three greenhouse pot experiments. Possible causes for the differing results between 2018 field and greenhouse studies will be explored in future research. Nematode Management Agent (NMA) Evaluation: Root-Knot Nematodes: A 2018 on-farm experiment evaluated control ofM. arenariaamong fumigant, non-fumigant, and biological nematicides. Compared to an untreated control, galling was significantly reduced by six or ten pounds of Telone II (1,3-dichloropropene [1,3-D] injected per acre, or by four pints of Nimitz (fluensulfone) sprayed and incorporated into a 16-inch band centered over the top of a pre-formed planting bed. Galling was intermediate when 1 pt/A Nimitz was applied in a 16-inch band before transplanting, followed by 6.1 fl oz/A Velum Prime (fluopyram) as a transplant water application. Similarly intermediate effects on galling were also observed for 76.4 fl oz/AVydate C-LV as a preplant incorporated treatment and for a preplant 500 lb/A rate of MBI-601 (Ennoble, a bionematicide based onMuscodor albus). Galling at the end of the growing season ranged from 35% to 65% for other treatments, including Nimitz at a banded rates of 2.1 or 6 pt/A. Similarly high levels of galling were also observed for 5.6 fl oz/A Velum Prime, 0.6 fl oz/A Aveo or 52.1 fl oz/A Q8U80 as transplant water treatments, and after application of 2 gal/A Majestene or 3-4 gal/A MBI-304 at transplanting, the first cultivation, and at layby. Tobacco Cyst Nematode (TCN -Globodera tabacum solanacearum): A 2018 field experiment evaluated the effects of 28 fumigant, non-fumigant, or biological nematicides on TCN populations in roots and soil and on tobacco growth. Although initial TCN populations averaged 15,784 eggs/500 cm3of soil, no statistically significant trends were found among treatments for any of the experimental variables observed. Estimated TCN soil populations in early July averaged 11,071 eggs/500 cm3of soil, while means for Q8U80, Aveo, a Promaxx-Zap-Promax program, 5, 7 or 9 gal/A Telone, some Nimitz treatments, a combination of Nimitz preplant and Velum Prime at transplanting, and the 500 lb/A MBI-601 treatment, were at or below approximately 10,000 TCN eggs/500 cm3of soil. In contrast, early July TCN soil populations averaged 11,188 in untreated control plots and ranged from 13,210 to 14,195 where low rates of Nimitz, Q8U80, or MBI-601 had been applied. Numerical trends in plant growth variables suggested that treatments involving 7 or 9 gal Telone II/A may have been associated with increased early season plant growth. Likewise, mid-June assessments of plant vigor and uniformity and plant height and number of leaves in early June suggested that 69 fl oz/A of the non-fumigant nematicide Q8U80, combinations of 5 gal Telone II with later use of 53 fl oz/A Q8U80, and the combination of 1 pt/A Nimitz in a 16-inch band preplant-incorporated with a 6.5 fl oz Velum Prime transplant water treatment may have been linked with greater plant size during the first 6-8 weeks of the growing season.
Publications
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
Johnson, C.S., Reed, T.D., and Clarke, C.T. 2018. Resistance to root-knot nematode in flue-cured tobacco cultivars in Virginia, 2017. Plant Disease Management Reports 12:N001.
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
Johnson, C.S. and N. Adamo. 2018. Tobacco growth after application of nematicides to control tobacco cyst nematodes in Virginia, 2017. Plant Disease Management Reports 12:N002.
- Type:
Other
Status:
Awaiting Publication
Year Published:
2018
Citation:
Johnson, C.S. 2019. Tobacco cyst nematode resistance in flue-cured tobacco in Virginia, 2018. Plant Disease Management Reports Vol. 13
- Type:
Other
Status:
Awaiting Publication
Year Published:
2018
Citation:
Johnson, C.S., Reed, T.D., and Clarke, C.T. 2019. Resistance to root-knot nematode in flue-cured tobacco cultivars in Virginia, 2018. Plant Disease Management Reports Vol. 13.
- Type:
Other
Status:
Awaiting Publication
Year Published:
2018
Citation:
Johnson, C.S., Reed, T.D., and Clarke, C.T. 2019.Evaluation of root-knot nematicides for flue-cured tobacco in Virginia, 2017. Plant Disease Management Reports Vol 13.
- Type:
Other
Status:
Awaiting Publication
Year Published:
2019
Citation:
Johnson, C.S., Reed, T.D., and Clarke, C.T. 2019.Evaluation of root-knot nematicides for flue-cured tobacco in Virginia, 2018. Plant Disease Management Reports Vol 13.
|
Progress 10/01/16 to 09/30/17
Outputs
Target Audience:This research is intended to provide farmers with effective new methods to control plant-parasitic nematodes of cultivated tobacco more safely with fewer potential risks to the environment. Plant breeders and extension agronomists can also use the information generated when developing new, improved cultivars and when advising farmers. Results may also apply to producers of other agricultural commodities that face similar problems, particularly crop production in fields infested by plant-parasitic nematodes. Changes/Problems:Some of the planned work for 2017 was delayed due to personnel changes in my program. While the research projects continued, publication and presentation of 2016 work was not possible due to time constraints. What opportunities for training and professional development has the project provided?A doctoral graduate student focusing on mechanisms of host resistance to root knot nematodesis being supported and mentored as a part of this project. Research results were also presented at the 2017 Flue-Cured TobaccoExtension In-Service training program and the Southern Piedmont AREC Field Day. How have the results been disseminated to communities of interest?Results have also been communicated to interested communities through the 2017 Southern Piedmont AREC field day, four tobacco grower meetings, a 2017 report to the Virginia Tobacco Board and to industry funding sources. Results were also incorporated into the 2017 Virginia Cooperative Extension Pest Management Guides for Field Crops and for Commercial Small Fruits and the 2017 Flue-Cured Tobacco Production Guide. More detailed reports were published in scientific peer-reviewed publications and a presentation at an industry-sponsored scientific meeting. What do you plan to do during the next reporting period to accomplish the goals?I plan to continue to collect data on using host resistance and nematode management agents to reduce the impacts of nematode parasitism. My graduate student will continue his doctoral research in 2018, evaluating new possible sources of resistance to root-knot nematodes, investigating the mechanisms involved in resistance conditioned by the Rk2 gene, and initiating phenotyping for genetic analyses of the Rk2 gene. I plan on communicating our results to all interested parties via similar venues to the recent past and to submit results to refereed journals for scientific publication.
Impacts
What was accomplished under these goals?
Seven breeding lines were compared to three commercial cultivars for resistance to root-knot nematode, primarily Meloidogyne arenaria. Percent galling on 4 November was significantly lower on all cultivars (CC 33 and CC 37) and breeding lines (XHN 72, XHN 60, XHN71, XHN 67, XHN 73, XHN 65, and XHN 58) possessing both of the root-knot resistance genes Rk1 and Rk2 versus NC 196, which possess only Rk1 (conferring resistance to races 1 and 3 of M. incognita). Although galling by M. arenaria was significantly suppressed by tobacco genotypes with both Rk1 and Rk2 in the field study, this trend wasn't apparent in three greenhouse pot experiments conducted by graduate student Noah Adamo to evaluate parasitism and reproduction by a different ('Aucuba') population of M. arenaria on seven other tobacco genotypes. Results were variable across the greenhouse trials, with less parasitism (fewer nematode egg masses/g of root) on root-knot susceptible cultivar 'Hicks' than on the Rk1Rk1Rk2Rk2 entry STNCB-2-28 in the first trial, no significant differences among entries in the second study, and higher parasitism of Hicks than on the Rk1Rk1Rk2Rk2 cultivar CC 13 in the third experiment. Trends in root-knot reproduction (number of root-knot eggs/g of root) were also highly variable and differed from those noted for parasitism. These results, in the context of previous research, suggest that within species variability may be an important factor in assessing the effectiveness of the resistance or tolerance conferred by Rk2 when combined with Rk1 to control M. arenaria. Preliminary work was also conducted to beginlaboratory and greenhouse experiments to determine the effect of Rk2 on M. arenaria migration, reproduction, egg deposition, and egg hatch. Experiments assaying the behavior and development of M. arenaria will use second-stage root-knot nematode juveniles of known age on a root-knot sensitive entry and others carrying Rk1, Rk2, or Rk1Rk2 to clarify the biological mechanism of resistance imparted by Rk2. Galled tissue will be harvested from plants at time points including 14, 21, 28, and 40 DAI and examined histologically for evidence of atypical giant cell and/or associated nematode development. The diameter of two to three giant cells per line will be measured at each time point to determine if and how the presence of different resistance genes affects the gross morphology and magnitude of feeding cell development. F4 plants from ~180 families of a cross between standard susceptible cultivar Hicks with T15-1-1 (source of the Rk2 gene in flue-cured tobacco germplasm) were advanced to the F5 generation to establish mapping populations that can be used to conduct genetic analyses of the effect of Rk2 on root-knot nematode parasitism and reproduction. Nematode Management Agent (NMA) Evaluation: Root-Knot Nematodes: Galling (primarily by M. arenaria) in an on-farm experiment comparing fumigant, non-fumigant, and biological nematicides was significantly reduced only by an 80 lb/acre (6 gal/acre) rate of Pic-Clor 80 (~20% 1,3-dichloropropene [1,3-D] and ~80% chloropicrin) compared to an untreated control. However, galling was significantly lower in plots treated with either 50 lb/acre (4 gal/acre rate) or 80 lb/acre Pic-Clor 80 or treated with 6.6 fl.oz./acre of Luna Privilege (a potential new reduced-risk non-fumigant nematicide) after fumigation with 5 gal/acre of Telone II (1,3-D) compared to that observed in areas treated once with Nimitz (a new non-fumigant nematicide), twice with Luna Privilege, or three times with Majestene (a biological nematicide). Increased crop development (% topping) was enhanced only by the 80 lb/acre rated of Pic-Clor 80 or 5 gal/acre of Telone II versus the untreated control. However, yield increases compared to the untreated control were only statistically significant when 5 gal/acre of Telone II and 2 gal/acre of chloropicrin were injected simultaneously during fumigation. Tobacco Cyst Nematode (TCN - Globodera tabacum solanacearum): Effects of fumigant, non-fumigant, and biological nematicides on tobacco growth varied across evaluation dates and were often not statistically significant from the untreated control. However, early season plant vigor was often greater in experimental plots treated with soil fumigants compared to non-fumigants and biological nematicides. Ennoble, a new biological nematicide, was an exception to this trend, ranking among the top five treatments for vigor on each of the five vigor evaluation dates. Product combinations of 1,3-D and chloropicrin tended to out-perform products containing only one of these fumigant active ingredients. Leaf fresh weights in mid-July were greater in plants sampled from plots treated with Ennoble or Telone C-17 than for plants from plots treated with Nimitz (fluensulfone, a recently registered reduced-risk non-fumigant nematicide) at transplanting. Crop development (% topped) was greater in mid-August for most fumigant treatments, Ennoble, MBI-304 (an experimental bionematicide), and Luna Privilege (fluopyram) compared to the untreated control. Yield differences compared to the untreated control ranged from an increase of 21.8% after fumigating with Telone II (1,3-D) and a field application of Luna Privilege, to a 12.2% lower yield associated with transplant water use of Nimitz (fluensulfone). Overall, percentage yield increases from fumigant treatments ranges from 0.2% to 21.8%, while yield differences linked to non-fumigant nematicides ranges from -12.2% to 13.1%. Mean yield increases observed for bionematicide treatments ranged from -10.2% to +16.2%.
Publications
- Type:
Other
Status:
Published
Year Published:
2017
Citation:
Cogar, L., Johnson, C.S., and Reed, T.D. 2017. Resistance to root-knot nematode in flue-cured tobacco cultivars in Virginia, 2016. Plant Disease Management Reports 11:N001.
- Type:
Other
Status:
Published
Year Published:
2017
Citation:
Cogar, L. and Johnson, C.S. 2017. Evaluation of nematicides for control of tobacco cyst nematodes in Virginia, 2016. Plant Disease Management Reports 11:N002.
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Progress 01/01/16 to 09/30/16
Outputs
Target Audience:This research is intended to provide farmers with effective new methods to control plant-parasitic nematodes of cultivated tobacco more safely with fewer potential risks to the environment. Plant breeders and extension agronomists can also use the information generated when developing new, improved cultivars and when advising farmers. Results may also apply to producers of other agricultural commodities that face similar problems, particularly crop production in fields infested by plant-parasitic nematodes. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Results from this research were presented at extension In-Service and grower education programs in 2016, as well as at the 2016 Southern Piedmont AREC Field Day, the 2016 annual meeting of the Regional Flue-Cured Tobacco Disease Resistance Evaluation Committee, and at the 2016 meeting of multi-state USDA project S-1066, "Integrate nematode management agents and cultural tactics with the use of resistant and/or tolerant cultivars to develop sustainable crop production systems." How have the results been disseminated to communities of interest?Field days; scientific peer-reviewed publications as noted in the Products section; and presentations at scientific meetings as per the above. What do you plan to do during the next reporting period to accomplish the goals?Collect data related to objectives, publish findings, and work with graduate students to develop a better understanding of the impacts of this study.
Impacts
What was accomplished under these goals?
Final galling results from the on-farm root-knot resistance experimenton 1 November was lowest on breeding line XHN60 and flue-cured tobacco cultivar CC13. Galling was also significantly lower on XHN65, CC33, CC35, XHN72, XHN73, CC37, XHN67, PVH2275, PVH2310, CC65, XHN71, XHN58, PVH1452, T-15-1-1, NC925, and Coker 371-Gold compared to that on CC1063. Galling was not significantly lower (statistically) on GL395 and NC196 to that on CC1063. However, no resistance to root-knot biotypes other than M. incognita races 1 and 3 is claimed for PVH2310, CC65, PVH1452, NC925, and Coker 371-Gold. These results should be very useful to plant breeders in advancing resistant breeding lines, and to growers for selecting cultivars most appropriate for the conditions in the fields ontheir farms. F4 plants are currently being maintained at the Southern Piedmont AREC to advance families of the Hicks*T15-1-1 cross to the F5 generation. Seed from these plants will enable us to advance the breeding lines to the next generation, eventually allowing us to clarify the inheritance of resistance to root-knot nematode biotypes other than races 1 and 3 of M. incognita. Early results from the 2016 tobacco farm survey for plant-parasitic nematodes has found much higher than expected populations of tobacco cyst nematode in multiple farms and fields in Halifax and Pittsylvania counties. These results will help Virginia Cooperatve Extension (VCE) enable farmersin selecting the mostappropriatecultivars for their fields, as well as whether or not they need to apply aNMA; and if so, which NMA to use in order to maximize nematode control, yield and crop quality. Although galling was observed in the root-knot NMA experiment at the end of the 2016 growing season, initial population densities of Meloidogyne spp. appeared very low. Pre-treatment populations of Pratylenchus were observed in a minority of experimental units, as well as ectoparasitic species such as stunt and spiral nematodes. Data was collected on nematode population densities, plant growth, root galling, and final fresh weight of leaves. No differences were observed among treatments in subjective ratings of vigor and uniformity (0-5) on 22 June or 7 July; in root galling on 8 July and 1 November; in plant height or number of leaves on 8 July; or in leaf fresh weight on 8 July or 5 October. Significant differences were observed among NMA treatments in the TCN NMA study in the number of juvenile nematodes/g of feeder root approximately 6 weeks after transplanting. TCN numbers in roots were lowest when Luna Privilege or Velum Total (both containing fluopyram) were applied, or where Telone II was injected. These results will guide labelling of potential new NMAs for growers, as well as VCE recommendations.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Pollok, J.R., Johnson, C.S., Eisenback, J.D., and Reed, T.D. 2016. Reproduction of Meloidogyne incognita race 3 on flue-cured tobacco homozygous for Rk1 and/or Rk2 resistance genes. Journal of Nematology 48(2):79-86.
- Type:
Other
Status:
Published
Year Published:
2016
Citation:
Darnell, L., and C.S. Johnson. 2016. Evaluation of nematicides for control of tobacco cyst nematodes in Virginia, 2015. Plant Disease Reports 10:N004.
- Type:
Other
Status:
Published
Year Published:
2016
Citation:
Darnell, L., and C.S. Johnson. 2016. Evaluation of nematicides for control of tobacco cyst nematodes in Virginia, 2014. Plant Disease Reports 10:N005.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Johnson, C.S. 2016. Potential new nematode management agents for tobacco production in Virginia. Joint Meeting of the Society of Nematologists and the Organization of Nematologists of Tropical America, Montreal, Canada. July 17, 2016.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Johnson, C.S. 2016. Managing tobacco nematodes using isothiocyanate products. CORESTA Congress, Berlin, Germany. October 10, 2016.
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