1. Nathan Schnur and Isaac Vohland 12/06/2007

2.  Genus Luteovirus  Spherical virus  Originated in Southeast Asia and Japan  Very significant disease in Japan  Severely reduces yield  If a field is infected it can result in a 80% yield loss Left: Isolated virus particles

3.  Recently found in Midwest  Illinois and Wisconsin  Only expected to have major impact in localized areas

4. Harrison, et al. 2005

5.  Four Strains  Dwarfing Strain  DS and DP  Yellowing Strain  YS and YP

6.  Soybean, Red Clover, White Clover, Sweetclover  Leaf puckering, yellowing, and stunting  Garden Pea  Mild yellowing of older leaves  Green Bean, Common Vetch  Leaf reddening  Beet  Leaf yellowing

7.  Overwinters in perennial clovers  Many clovers on ditch banks in Midwest  Close proximity to soybean fields

8.  Aphids are only known vectors  Species of aphids responsible for transmission  Strains YS and DS are transmitted by the fox glove aphid ( Aulacorthum solani)  Strains YP and DP are transmitted by both the pea aphid ( Acyrthosiphon pisum) and clover aphid ( Nearctaphis bakeri ) Fox Glove Aphid Pea Aphid

9.  Disease Cycle  Circulative-Persistently transmitted  Retained when aphid molts  Take 10-30mins to ingest the virus  Latency Period of 15-27h

10.  There are several management practices which are useful to control SbDV.  Resistance  Vector Control  Alternate Host Control

11.  Resistance  Transgenic resistance to SbDV  Resistance stems from the insertion of the SbDV coat protein into the soybean genome  This insertion caused RNA silencing (RNAi)  Natural Resistance to SbDV  Some natural resistance has been located in germplasm in Japan  It will take some time for any stable resistance to stem from it

12.  Vector control is centered around controlling aphid populations.  Best way to control aphid populations is with use of pesticides.  There are no soybean cultivars which are 100% resistant.  Pesticides  Asana  Warrior

13.  Host Control  Alternate hosts which are of most concern  Red clover, white clover, and yellow sweetclover  Removal of alternate hosts from the immediate vicinity can greatly reduce inoculum.  Do not plant soybeans in close proximity to fields of clover or other legumes

14.  Present in Midwest, but not yet serious problem  This may change if the vectors become more prevalent

15.  References  Kojima, M. and Tamada, T. Soybean Dwarf Virus. 1977. http://www.dpvweb.net/  Tamada, T. Soybean Dwarf Luteovirus. 1980. http://images.fs.uidaho.edu/vide/descr740.htm  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 Dis. 89:28-32.  ICTVdB Management (2006). 00.039.0.01.015. Soybean dwarf virus. In: ICTVdB - The Universal Virus Database, http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/. version 4. Büchen-Osmond, C. (Ed), Columbia University, New York, USA  Yamagishi N, Terauchi H, Honda K, Kanematsu S, Hidaka S (2006). Discrimination of four soybean dwarf virus strains by dot-blot hybridization with specific probes. J Virol Methods 133:219–222  Photos Courtesy of:  http://www.genome.ou.edu/  http://www.wildmanstevebrill.com/JPEG'S/Plant%20Web%20Images/YellowSweetCloverFlowers.jpg  http://www.gardenorganic.org.uk/assets/organicweeds/t_repens2.jpg  http://www.netstate.com/states/symb/flowers/images/red_clover2.jpg  http://www.ces.ncsu.edu/plymouth/graphics/ent/soyapslide06/Slide2.JPG  http://www.agri.pref.hokkaido.jp/tokachi/soy/index-e.html  http://www.tolweb.org/tree/ToLimages/Aphid4_mod.250a.jpg  http://www.agric.wa.gov.au/ikmp/images/Aphis_solani2.jpg  http://www.apsnet.org/Education/IllustratedGlossary/PhotosA-D/circulativetransmission.jpg  http://www.illinoiswildflowers.info  http://i.ehow.com  http://www.discoverlife.org/