Duration: 10/01/2006 to 09/30/2011

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

Virus diseases of soybean are emerging disease problems with significant impacts on soybean production in the North Central (NC) region, the principal soybean producing area of the United States. On initiation of the current committee, little was known about the incidence or impact of soybean viruses in the NC region. However, some of these viruses were found in near epidemic levels in many NC states causing significant losses for producers. These losses included yield reduction, decreased pod and seed set, reductions in oil percentage of the seed, and seed discoloration (associated with financial penalties at local elevators and unsuitability for some markets). This emerging outbreak is paralleled by the northward migration of the insect vectors associated with these viruses. For example, mild winters of the past few years have allowed populations of the bean leaf beetles (BLB), which efficiently transmits Bean pod mottle virus (BPMV), to overwinter at unprecedented levels. Another complicating factor is the newly introduced soybean aphid, which has been shown to transmit Soybean mosaic virus (SMV) and Alfalfa mosaic virus (AMV). Emergence of unsuspected viruses in NC soybean, such as Tobacco streak virus (TSV) and Soybean dwarf virus (SbDV), have also added further complications to this situation. A review of the current information detailing NC soybean virus incidence and distribution and discussion soybean virus management is given in the following subsections, and review of the current committees work can be found in the Attachments.

Soybean virus incidence and distribution

Bean pod mottle virus: BPMV is the most common and widespread viral pathogen of soybean in the NC region. In Indiana during 2001, 60% of soybean plants with virus-like symptoms tested were infected with BPMV. Similarly,70% of randomly collected soybean leaf samples from 32 Nebraska counties were positive for BPMV in 2001 (20) and 87% of fields were positive for BPMV in 2002 (21). In Iowa, a survey during 2000 detected BPMV in 73 of 80 counties. In Illinois, 37 of 41 counties in 2000 and 86 of 99 counties in 2001 tested positive for BPMV. In Wisconsin surveys conducted in 1999, 1% of samples tested were positive for BPMV, but increased to 38% in 2000 (11). In South Dakota, the percent of infected plants per field ranged from 0 to 94% with an average peak incidence of 44% in August (10). In contrast, North Dakota surveys of soybean fields in 2001 and 2002 failed to detect the presence of BPMV (13). BPMV was reported for the first time in Canada during 2001(12). The differences in BPMV incidence seen from year to year and among locations likely reflect differences in the size and distribution of bean leaf beetle populations, the principal vector of BPMV (5).

Soybean mosaic virus: SMV is one of the most widely distributed soybean-infecting viruses. The incidences of SMV infection in the NC region have been much lower than those for BPMV. In Indiana during 2001, 6% of soybean plants with virus-like symptoms tested positive for SMV. In Wisconsin surveys, SMV was detected in 7% and 54% of the soybean plants tested in 1999 and 2000, respectively. Similarly, in Nebraska surveys, SMV was found in 0% and 35% of soybean fields tested in 2001 and 2002, respectively. In Illinois during 2000 and 2001, SMV was detected in one county each year. While no widely dispersed perennial alternative hosts have been identified for SMV in North America, SMV is readily transmitted through seed. In addition, multiple studies have shown that SMV is transmitted efficiently by soybean aphids following short feeding periods (1,3,8). However, the efficiency of aphid transmission of SMV declines dramatically following longer feedings (18).

Alfalfa mosaic virus: AMV infections have been detected at high levels in Nebraska (40% and 26% of fields in 2001 and 2002, respectively) and Wisconsin (28% and 13% of fields in 1999 and 2000, respectively) (4,11,21). AMV infection rates in Illinois and Indiana have been less than 1% (1,9). The apparent differences in incidence of AMV between Nebraska, Wisconsin, Indiana and Illinois recently have been linked, at least in part, to the antibody preparations used for virus detection. Like SMV, AMV is readily transmitted through seed and by soybean aphids, (1,7,8,17). Because alfalfa and clover plants in the NC region are commonly infected with AMV, it is possible for the incidence of AMV in soybean to increase more rapidly than that of SMV following the introduction of soybean aphids.

Soybean dwarf virus: SbDV, which causes severe soybean yield losses in Japan (16), has been detected in Wisconsin associated with heavy infestations of soybean aphids. In 2003, SbDV was detected in about 2% of soybean fields. At all of the locations in Wisconsin where SbDV-positive samples were identified, all soybean plants were infested with soybean aphids (14). Similar levels of SbDV infection were observed in 2004 and 2005. In Illinois, over 1000 soybean plants were tested for SbDV in 2001 and 2002, but none were positive for SbDV (6). At the same locations in Illinois, SbDV was detected in 43% of red clover, 10% of white clover, and 3% of yellow sweet clover plants. In 2005, soybean aphids were shown to transmit SbDV among soybean plants (2), and this could explain the emergence of the virus in soybean-growing regions of Wisconsin that have had consistently high soybean aphid populations.

Tobacco streak virus: TSV is transmitted by thrips and can significantly reduce soybean yields (15). In Wisconsin, TSV was detected in 21% of plants tested in 1999, 18% of plants in 2000, and 45% of plants in 2001, but was not detected in 2002 (11,15). TSV was not detected in Indiana during 2000 or North Dakota during 2002 and was detected in only one sample in Illinois during 2001 (1,13). Analysis of TSV epidemics illustrated that virus incidence as determined by enzyme-linked immunosorbent assay (ELISA), appeared to increase and then decrease over time (15). These results illustrated a problem of virus detection that, while more pronounced with TSV, occurs with other soybean-infecting viruses including AMV, BPMV and SbDV (6,10,17). Since virus titers vary significantly over time, the point during infections at which samples are analyzed for virus infection can affect the ability to detect viruses. Even though soybean plants sometimes appear to recover from AMV and TSV infections, both viruses are still capable of being transmitted through seed and reducing yields (15).


Current status of soybean virus management:

The ability to reduce the impact of virus disease in soybeans has historically been problematic due to the nature of virus diseases and the lack of therapeutic treatments. Nevertheless, progress has recently been made with BPMV, and SMV, but little information is available on AMV, SbDV, and TSV.

Bean pod mottle virus: Significant efforts have been focused on management of disease caused by BPMV, which is widespread in all areas during some years. No resistance genes have been identified in cultivated soybean. Sources of the virus may include alternative weed hosts, seed transmission, and perhaps beetles that survive winters under leaf debris. Their relative importance is unknown. Emphasis has been placed on management of the BLB, the primary vector of the virus. Research has suggested that well-timed applications of foliar insecticides can protect yield and improve seed quality. Success has been achieved using the insecticide Warrior applied at soybean emergence and at emergence of the first generation of BLBs. Growers in some regions have utilized this strategy with success. Studies utilizing insecticide seed treatments are still in progress, and data are incomplete. Alteration of planting date has not been consistently successful for disease control. Several investigators are using varying strategies to identify field tolerance in soybean cultivars and breeding lines. Results from these studies may have significant impact on improving disease control.

Soybean mosaic virus: SMV is transmitted through soybean seed at levels approximating 0  5% in most commercial varieties. This most likely constitutes the primary inoculum source of the virus in the northern states. Three resistance genes have been identified in soybean germplasm lines to SMV, but they have generally not been incorporated into northern soybean lines. When soybean plants are infected with both BPMV and SMV, symptoms are more severe than infection by either virus alone and usually results in complete loss of yield from the plants infected with both viruses. Introduction of the soybean aphid, an efficient SMV vector, has the potential to increase the incidence of SMV infections and plants doubly infected with BPMV and SMV. Thus, the need for incorporation of SMV resistance into northern lines is increasingly critical.

Alfalfa mosaic virus: AMV is becoming increasingly common in soybeans. The primary source of this virus is unclear, as is its impact on yield. Seed transmission is known to occur. At least one soybean line has been identified that is resistant to at least one AMV isolate. However, it is susceptible to other isolates of the virus.

Tobacco streak virus: TSV has been shown to occur widely in production trials in certain regions. The source of the virus and its impact on a commercial scale are unknown. Almost all varieties tested have been susceptible. Recently, Wang et al. (19) identified a soybean line that is resistant to the Illinois isolate of TSV, but it has not been tested against additional TSV isolates yet.
Summary
Soybean viral diseases in the NC region represent the actions of several viruses interacting in a dynamic and developing disease situation with the potential to cause severe economic losses for soybean producers. As this situation progresses, viruses that have entered the states as emerging new epidemics have the potential to become established as long-term endemic disease problems that have debilitating effects on NC soybean production. The committee seeks to develop an understanding of these diseases and their epidemiology and pathology and to provide management strategies for these diseases through a multi-state, multi-disciplinary effort composed of virologists, plant pathologists, entomologists, and agronomists. Currently, annual meetings, sponsored by the North Central Soybean Research Program in coordination with this committee, have assisted in reviewing information that is known, discussing what is still not known, and developing priorities for future research. Through continuation of its work, the committee will strive to minimize the risk from these diseases to NC soybean producers. An NCERA committee will provide the administrative, communication, and educational structures required for bringing leading researchers together to accomplish these goals and objectives.

Objectives

Procedures and Activities

Meetings for the committee and interested researchers, soybean growers, and industry, commodity group representatives will be held annually to share progress and preliminary results from research funded by other agencies. In conjunction with these meetings, symposia will be organized that will highlight topics relevant to the management of soybean virus diseases.

Based on the results of the annual meetings, fact sheets and web pages will be prepared that describe the distribution of viruses and their vectors in the North Central Region. As replicated data become available on host resistance and other management strategies, that information will be incorporated into media produced by the committee.

Expected Outcomes and Impacts

Projected Participation

View Appendix E: Participation

Educational Plan

Communication of the findings of this committee to producers and commercial field managers will be done through fact sheets, web site materials, field days, and educational offerings in meeting format. Surveys of the impact of information delivered will occur, depending on fund availability. Specific educational offerings will be based on geographic location and the viral diseases known to occur in the area.

Organization/Governance

The recommended Standard Governance for multistate research activities includes the election of a Chair, a Chair-elect, and a Secretary. All officers are to be elected for at least one-year terms. Administrative guidance will be provided by an assigned Administrative Advisor and a CSREES Representative.

Literature Cited

1. Clark, A. J., and Perry, K. L. 2002. Transmissibility of field isolates of soybean viruses by Aphis glycines. Plant Disease 86:1219-1222.
2. Damsteegt, V., Stone, A., Schneider, W., Sherman, D., Gildow, F., and Luster, D. 2005. The soybean aphid, Aphis glycines, a new vector of endemic dwarfing and yellowing isolates of Soybean dwarf luteovirus. Phytopathology 95:S22.
3. Domier, L. L., Latorre, I. J., Steinlage, T. A., McCoppin, N., and Hartman, G. L. 2003. Variability and transmission by Aphis glycines of North American and Asian Soybean mosaic virus isolates. Arch. Virol. 148:1925-1941.
4. Doughty, D. M., Lee, M. E., Kurtzweil, N. C., Boerboom, C. M., and Grau, C. R. 2000. Occurrence of soybean viruses and association with green stem of soybean in Wisconsin. Paper read at North Central Division Meeting of the American Phytopathological Society, at Columbus, OH.
5. Giesler, L. J., Ghabrial, S. A., Hunt, T. G., and Hill, J. H. 2002. Bean pod mottle virus: a threat to U.S. soybean production. Plant Dis. 86:1280-1289.
6. Harrison, B., Steinlage, T. A., Domier, L. L., and D'Arcy, C. J. 2005. Incidence of Soybean dwarf virus and identification of potential vectors in Illinois. Plant Disease 89:28-32.
7. Hill, J. H. 1999. Soybean Mosaic Virus. In Compendium of Soybean Diseases, eds. G. L. Hartman, J. B. Sinclair and J. C. Rupe. St. Paul, MN: The American Phytopathological Society.
8. Hill, J. H., Alleman, R., Hogg, D. B., and Grau, C. R. 2001. First report of transmission of Soybean mosaic virus and Alfalfa mosaic virus by Aphis glycines in the new world. Plant Disease 85:561.
9. Hobbs, H. A., Hartman, G. L., Wang, Y., Hill, C. B., Bernard, R. L., Pedersen, W. L., and Domier, L. L. 2003. Occurrence of seed coat mottling in soybean plants inoculated with Bean pod mottle virus and Soybean mosaic virus. Plant Dis. 87:1333-1336.
10. Langham, M. A. C., Doxtader, D. C., Smolik, J. D., and Scott, R. A. 1999. Outbreak of a viral disease affecting soybeans [Glycine max (L.) Merrill] in South Dakota. Phytopathology 89:S43.
11. Lee, M. E., Kurtzweil, N. C., and Grau, C. R. 2001. Prevalence and agronomic effects of viruses in Wisconsin soybeans. Paper read at North Central Division Meeting of the American Phytopathological Society, at Manhattan, KS.
12. Michelutti, R., Tu, J. C., Hunt, D. W., Gagnier, D., Anderson, T. R., Welacky, T. W., and Tenuta, A. U. 2002. First report of Bean pod mottle virus in soybean in Canada. Plant Dis. 86:330.
13. Nelson, B. D., and Danielson, G. A. 2004. Soybean virus survey in North Dakota. Phytopathology 95: S164-165.
14. Phibbs, A., Barta, A., and Domier, L. L. 2004. First report of Soybean dwarf virus on soybean in Wisconsin. Plant Dis. 88:1285.
15. Rabedeaux, P. F., Gaska, J. M., Kurtzweil, N. C., and Grau, C. R. 2005. Seasonal progression and agronomic impact of Tobacco streak virus on soybean in Wisconsin. Plant Disease 89:391-396.
16. Tamada, T., Goto, K., Chiba, I., and Suwa, T. 1969. Soybean dwarf, a new virus disease. Ann. Phytopathol. Soc. Jap. 35:282-285.
17. van Vloten-Doting, L., and Gibbs, A. J. 1987. Alfalfa mosaic alfamovirus. In Plant Viruses Online: Descriptions and Lists from the VIDE Database, edited by A. A. Brunt, K. Crabtree, M. J. Dallwitz, A. J. Gibbs, L. Watson and E. J. Zurcher.
18. Wang, R. Y., and Ghabrial, S. A. 2002. Effect of aphid behavior on efficiency of transmission of Soybean mosaic virus by the soybean-colonizing aphid, Aphis glycines. Plant Disease 86:1260-1264.
19. Wang, Y., Hobbs, H. A., Hill, C. B., Domier, L.L., Hartman, G. L., and Nelson, R. L. 2005. Evaluation of ancestral lines of U. S. soybean cultivars for resistance to four soybean viruses. Crop Science 45:639-644.
20. Ziems, A. D., Giesler, L. G., and Lane, L. C. 2001. Incidence of Bean pod mottle virus and Soybean mosaic virus in Nebraska. Paper read at North Central Division Meeting of the American Phytopathological Society, at Manhattan, KS.
21. Ziems, A. D., and Giesler, L. J. 2003. Incidence of Bean pod mottle virus and Alfalfa mosaic virus in Nebraska soybean fields. Paper read at North Central Division Meeting of the American Phytopathological Society, at East Lansing, MI.

Attachments

Land Grant Participating States/Institutions

AR, IA, IL, KY, MN, MO, ND, NE, OH, SD, TN, VA, WI

Non Land Grant Participating States/Institutions

Agriculture and Agrifood Canada, Iowa Soybean Association, Ontario - ON MInistry of Agriculture, Food and Rural Affairs, Soybean Meal Information Center, USDA-ARS-Urbana, USDA-ARS/Ohio