Agronomic SCN Management Handbook An introduction to SCN and the actions you can take to reduce the costly damage. For more information, visit SyngentaFarm.ca, contact our Customer Interaction Centre at 1-87-SYNGENTA (1-877-964-3682) or Agronomic SCN Management Handbook follow @syngentacanada on Twitter and tweet us your questions using #AskSYN.

How serious is SCN? This Agronomic SCN Management Handbook is designed as a brief introduction to soybean cyst nematode “…the most common (SCN) and the actions you can take toward its management. In Canada, SCN is spreading in soybean SCN losses are growing areas. In the U.S., extension nematologists and plant pathologists estimate that SCN robs more not obvious enough yield annually than the next five soybean pathogens combined, with an estimated $1.5 billion in annual to be visible from soybean yield losses.1 above-ground s y m p t o m s .” 3 According to the University of Illinois, SCN can lead to losses up to 80 percent.2 However, the most common SCN losses are not obvious enough to be visible from above-ground symptoms. This means your soybean yields may be reduced by SCN while you’re not even aware of it. It is not uncommon for SCN to reduce yields by up to 40 percent without any visible above-ground symptoms.4 What’s more, SCN symptoms are often confused with other common problems such as nutrient deficiencies, chemical injury, soil compaction, drought, flooding or root rots.5 Once SCN is introduced into a field, it can never be eradicated – when you have it once, you have it forever. Because of that, it is a pest that must be managed; otherwise, it will eventually become a significant problem. Your losses associated with SCN in any given year will be directly dependent on environmental factors beyond your control, such as drought or other natural events. However, through planning and use of SCN management strategies, L a k e H u r o n Wilberforce Torrance 121 6 Minden you can reduce the impact of these SCN-related losses. 23 69 Gravenhurst 11 Gooderham Port Severn 35 Shows SCN presence in Ontario based on 273 samplesPenetanguishene Since it was first identified in Ontario in 1988, SCN has been identified in most counties west of Toronto Wiarton Kinmount FigureMikado 1.H Showsarrisville SCN presence in Ontario based on 273 samples. Midland Port Mcnicoll Washago 7 Norland and more recently in parts of Eastern Ontario (see Figure 1). Unfortunately, as with other soybean Owen Meaford Coboconk35 Sound 26 Elmvale Orillia 26 Brechin Buckhorn production areas around the world, SCN does not stop moving and will eventually spread to all Southampton Allenford Thornbury Oscoda 6 Hawkestone Fenelon Falls soybean production areas of Ontario.7 Dramatic yield losses from SCN will continue to trend Port Elgin Collingwood Lake Dobbinton Simcoe 12 21 Stayner 26 Barrie 10 Lakefield upwards in the coming years. Tawas City Markdale Innisfil Lindsay Chesley Angus 28 Paisley 4 Creemore Essa Mariposa Hastings Elmwood 7 7 Flesherton Borden 400 Sutton Peterborough Kincardine Durham 10 26 35 9 4 Keswick Cavan Keene Walkerton Alliston Scugog Port Austin Hanover Dundalk Millbrook 25 21 Ripley East Gwillimbury 44˚ 12 Harwood Mildmay Shelburne Port Perry 86 Pontypool 25 Teeswater Lucknow Mount Forest Newmarket 9 Stouffville 35 Pigeon Clifford Gormley Harbor Beach 6 Orangeville Clarington Bad Axe Wingham Harriston Caledon Cobourg 9 9 26 Oshawa 401 Newcastle Sebewaing Palmerston Arthur Inglewood Goderich Brussels 86 North York Scarborough 10 8 4 Cass City Listowel Fergus Brampton York East York Clinton 23 6 53 Floradale Acton 21 Milverton Mississauga Caro Seaforth 86 Guelph 401 Toronto 46 46 Sandusky Milton Hensall Waterloo Mitchell Marlette 8 Kitchener Baden 8 8 Puslinch Oakville 25 Exeter Croswell Grand Bend 23 Stratford Flamborough Cambridge 6 Michigan Centralia St. Marys Tavistock Niagara-on Bosanquet Hamilton Burlington Burt 4 Drumbo -the-lake Albion 53 Yale Parkhill Lucan Paris Youngstown Thedford 18 Lapeer Woodstock 403 Ancaster Grimsby Lockport Medina Forest Denfield Burford 43˚ 4 Brantford St. Catharines 69 Sarnia 21 Ingersoll Niagara Falls Almont 402 Caledonia Niagara Falls London Norwich Akron Marysville Port Huron Strathroy Welland Batavia 401 Haldimand 90 Oxford 94 79 Romeo Richmond Petrolia Caradoc Glanworth Nanticoke 3 Fort Erie Crittenden 24 40 Tillsonburg Buffalo 20 53 St. Clair 3 Dunnville 75 Muncey St. Thomas Selkirk Port 24 Marine City Simcoe Pontiac 94 59 Sterling Sombra Aylmer Port Dover Colborne Mount Vernon East Aurora 59 Port Ryerse Florence Fingal Highland-on-the-lake Heights Sparta Port Burwell 90 75 3 Armor Silver Lake 2 Rodney 695 Warren West Lorne Port Rowan Farnham 16 Muirkirk 219 24 Lake Ridgetown Springville 96 Detroit Dunkirk 94 Saint Clair Chatham Gowanda 12 Windsor Rondeau Park 90 Fredonia Taylor 3 Blenheim 94 Tilbury Westfield 401 3 219 Lasalle 3 Essex Comber Erieau Trenton Mayville Little Valley 24 Belmont Amherstburg Wheatley 20 75 Salamanca Kingsville L a k e E r i e Erie 86 42˚ Leamington 90 86 79 Lakewood Jamestown Allegany Olean 20 417 Conneaut 322 Lexington Corry Corydon Ashtabula Union City 62 90 Albion Bradford 20 6 Warren Source:6 Syngenta Canada219 2015 Geneva 11 7 Cambridge Springs Youngsville Port Allegany SCN eggs/100g of soil Grand River 322 Painesville Jefferson Clarendon Mentor-on-the-lake Roulette Maple Grove 20 1-500 Willoughby Mentor Tidioute 6 Barnes Corne6rs Meadville 90 6 6 AlleghenySheffield Sh5e0ld1o-2000n Piccola Kane 90 Wickliffe Beardsley Titusville Port Clinton Cleveland 322 De Young 80 2001-4000 Sandusky Lorain Pepper Pike 62 20 6 Sheffield Lake 62 Dewey Emporium 4000+ Marienville Clearview Brooklyn 11 Oil City Tionesta Solon York Greenville Elyria 80 Northfield Ohio Franklin Clyde Bellevue Wassie Woodland Heights Ridgway Saint Marys Pennsylvania 20 62 20 Oberlin Macedonia 62 7 79 219 Norwalk Cortland 322 Dagus Agronomic SCN Management Handbook

SCN biology Figure 2. Soybean cyst nematode egg What is SCN? SCN are microscopic roundworms that invade and parasitize soybean roots. There are three major life cycle stages of SCN: egg, juvenile and adult. The egg is the overwintering SCN stage that hatches as a juvenile roundworm and is attracted to the young, developing root within days of soybean seed germination (see Figures 2–3).

SCN juveniles enter the soybean root and move toward the vascular tissue, which transports moisture and nutrients throughout plant. Here they modify SCN eggs with juveniles ready to hatch Source: Iowa State University plant cells and begin to feed by drawing nutrients Figure 3. Soybean cyst nematode juvenile from and damaging their host. SCN continues to feed within the root but eventually the juveniles become male or female. The males exit the root tissue while the female remains and grows large enough to burst from within the root while they continue to feed, with the largest portion of the developing body exposed on the root exterior (see Figure 4).8

The young, exposed, developing female is initially white in color but becomes yellow to brown with age. Following fertilization, the female produces up to 200–500 eggs. As her life cycle is completed, the Source: Iowa State University female dies and her body changes from yellow to Figure 4. Soybean cyst nematode adult female brown. At the same time, some mature SCN eggs begin the life cycle once again, depending on environment (see Figure 5).8 The female body following death becomes the familiar “cyst” structure, How SCN reduces yield which can act as a long-term, resilient casing that SCN reduces soybean performance and yield in infection is often the most significant potential season- overwinters and can last for years. SCN is more several ways. The primary means is the direct effect long effect on soybean performance. So not only is likely to resist control measures because the many of the SCN juveniles establishing themselves within root area reduced on infected plants, but the existing different hatch periods spread across time increase the root and the associated vascular plant tissue root area is not as efficient in foraging the root zone the chances of successful life cycle completion.3 disruption. As the juveniles develop into full-grown for much-needed moisture and nutrients due to the SCN can complete up to six generations based adults, the efficiency of moisture and nutrient transport disrupted internal vascular tissue damage from SCN. Source: Iowa State University primarily on the following (in no particular order):6 within the infected plant is drastically affected. These two effects combined are predictably among Secondary effects of SCN infection include: the most significant to soybean yield reduction. Figure 5. Soybean cyst nematode life cycle • Planting date adult female • Soil temperature • Stunting and damage of developing A reduction of nitrogen-fixation caused by SCN cyst • Host suitability soybean root system reducing Rhizobium bacteria efficiency also leads • Geographic location • Reduction of nitrogen-fixing Rhizobium to reduced yield potential. As SCN enters plant roots, • Presence of alternative hosts bacteria root nodules it promotes the secondary effect of an increase in adult male egg • Length of growing season • Disease introduction through SCN root-attacking pathogen infection. One example soybean entry points within the root of this is Fusarium virguliforme, the causal organism root During the soybean growing season, the most typical developing • Stress interactions with any number of pests of Sudden Death Syndrome (SDS). This disease is juvenile SCN life cycle can be completed in 24–30 days, unhatched which flare within stressed soybeans often closely associated with SCN. Other diseases based largely on environmental conditions such as juvenile in associated with SCN are brown stem rot, Pythium, egg temperature and moisture levels. Cooler temperatures Young, developing roots are stunted when infected Phytophthora and Iron Deficiency Chlorosis (IDC). penetrating and adequate moisture enhance reproduction. by SCN. These young roots do not reach their genetic hatching juvenile juvenile maximum potential for root expression, and early Source: Iowa State University For more information, visit SyngentaFarm.ca, contact our Customer Interaction Centre at 1-87-SYNGENTA (1-877-964-3682) or Agronomic SCN Management Handbook follow @syngentacanada on Twitter and tweet us your questions using #AskSYN.

SCN management Protect against SCN with Although SCN can have drastic effects on soybean yield, Controlling these six weeds should be an important seed-applied nematicides there are management strategies you can take that have goal within any farm’s SCN management program. TM predictably positive results over time. These include: Syngenta offers Clariva pn seed treatment, which Rotation with non-host crops provides season-long control of all SCN populations. • SCN soil sampling every 3–5 years Non-host crop rotation is a foundational principle in Growers have the flexibility to choose either Clariva pn • Weed management managing SCN. Use of non-host crops provides the with Vibrance® Maxx seed treatment or Clariva pn with • Rotation with non-host crops unique opportunity to reduce field-wide SCN numbers Cruiser Maxx® Vibrance® Beans seed treatment for broad- • Use of SCN-resistant soybean varieties by disturbing the SCN life cycle. spectrum early-season insect and disease protection. • Rotation of SCN-resistant sources Use of SCN-resistant soybean varieties • Use of seed-applied nematicides If SCN is present and you plan to plant soybeans, To use a sports analogy, would you play an entire SCN-resistant varieties are strongly recommended. round of golf using only one club if you had other SCN-resistant varieties reduce the ability of SCN to clubs available that could improve your game? successfully colonize the soybean root, leading to a + In the same way, there are several tools available to reduction of the SCN reproduction rate. If susceptible the soybean grower that, when combined, provide soybean varieties are used in SCN environments, improved performance in an SCN environment. predictable increases in SCN levels will occur. Since SCN has multiple generations per growing season, or Soil sampling Initially, SCN soil sampling is recommended to provide the more you grow SCN-susceptible soybeans in the a baseline. Then, a regular soil sampling program once presence of SCN, the greater the risk of SCN exploding every 3–5 years will provide you with a picture of into a significant yield-limiting pest. Also keep in mind + whether your management practices are producing when selecting SCN-resistant varieties that they are the desired result. Soil sampling is reported to be the not all created equal. Seed companies provide tolerance most reliable means of confirming and monitoring scores on the degree to which their varieties are able SCN levels.9 However, due to the irregular distribution to limit reproduction by SCN based on testing on their of SCN in a field, the SCN count from a soil sample own selection of SCN populations. Universities might could be misrepresenting the SCN pressure in that offer additional data on variety resistance, but the only field. Therefore, it’s best to use soil sampling as a means true testing of the effectiveness of genetic resistance to confirm presence of SCN and changes in SCN is to plant them in your fields. pressure over multiple years, rather than an accurate The genetic sources for SCN resistance are very limited estimation of SCN pressure and possible action and not all have acceptable agronomic or seed quality threshold. Specific soil sampling guidelines are available traits, and are not often used in commercial plant from your local, private or university nematode laboratory. breeding programs. Due to this limited pool of genetic SCN resistance, one source of commercially acceptable Weed management Soybeans are not the only host for SCN. An Indiana SCN resistance, designated as Plant Introduction 88788 agricultural field survey determined that known SCN-host (PI 88788), has been very heavily relied upon across winter weeds were present in 93 percent of surveyed the industry. fields.10 According to Purdue University Extension, there PI 88788, introduced in the 1980s, is the SCN resistance 1 Wrather, J.A., T.R. Anderson, D.M. Arsyad, J. Gai, L.D. Ploper, A. Porta-puglia, H.H. Ram and J.T. Yorinori. 1997. Soybean disease loss estimates are six known winter weeds that allow various levels source for the majority of SCN-resistant varieties offered for the top 10 soybean producing countries in 1994. Plant Dis. 81:107-110. 11 2 University of Illinois. Report on Plant Disease. RPD 501. of successful SCN reproduction: for sale across all seed soybean companies. Unfortunately, 3 Schmitt, D.P., J.A. Wrather and R.D. Riggs. 2004. Biology and management of soybean cyst nematode. 2nd Edition. Schmitt & Associates of Marceline. this heavy reliance on a single source of SCN resistance 4 Pedersen, P. Managing Soybean Cyst Nematode. Iowa State University • Purple deadnettle (strong host) 5 Ontario Soil and Crop Improvement Association. 2006. SCN Detection in Non-Infested Counties of Ontario. Crop Advances: Field Crop Reports. has led to the SCN population adapting to PI 88788 so 6 Niblack, T.L. and G.L. Tylka. SCN Management Guide 5th Edition. Plant Health Initiative – A North Central Soybean Research Program. • Henbit (strong host) 7 Ontario Ministry of Agriculture, Food and Rural Affairs. 2009. Diseases of Field Crops: Soybean Diseases. OMFRA Publication 811: Agronomy Guide for Field Crops. that it no longer offers the SCN protection it once did. 8 Tylka, G. L. 2012. Soybean cyst nematode field guide 2nd Edition – Iowa State University Extension and Outreach. • Field pennycress (moderate host) 9 Faghihi, J., and V. R. Ferris. 2006. Soybean cyst nematode. Department of Entomology. Purdue University. Multiple universities have published research on SCN 10 Creech, J. E., and W. G. Johnson. 2006. Survey of broadleaf winter weeds in Indiana production fields infested with soybean cyst nematode (Heterodera glycines). • Shepherd’s purse (weak host) Weed Technol. 20:1066-1075. populations in their state adapting to PI 88788 and 11 • Small-flowered bittercrest (weak host) Mock V.A., J.E. Creech, B. Johnson, J. Faghihi, V.R. Ferris, A. Westphal and K. Bradley. 2007. Winter annual weeds and soybean cyst nematode management. increasing their reproduction on varieties using that Purdue University Extension bulletin WS-36. • Common chickweed (weak host) source of resistance. Because of this, it is often Scientists at Purdue report from their greenhouse recommended that you attempt to purchase non-PI studies that purple deadnettle and henbit are such For more information, visit SyngentaFarm.ca, contact our Customer Interaction Centre at 1-87-SYNGENTA (1-877-964-3682) 88788-sourced SCN-resistant soybeans in an effort or follow @syngentacanada on Twitter and tweet us your questions using #AskSYN. strong alternative hosts that they support similar levels to rotate SCN resistance sources and help manage Always read and follow label directions. Cruiser Maxx Vibrance Beans is an on-seed application of Cruiser Maxx Beans Seed Treatment insecticide/fungicide and Vibrance 500 FS Seed 11 of SCN reproduction as SCN-susceptible soybeans. Treatment fungicide. Vibrance Maxx is an on-seed application of: (i) Vibrance 500FS Seed Treatment fungicide; and (ii) Apron Maxx RTA Seed Treatment Fungicide or Apron Maxx RFC Seed this continued decline in SCN resistance. Treatment Fungicide. Soybean seeds treated with thiamethoxam are classified as a Class 12 pesticide in Ontario. Soybean seeds which are not Class 12 pesticides are also available for sale from Syngenta. Clariva™, Cruiser Maxx®, Vibrance® and the Syngenta logo are trademarks of a Syngenta Group Company. © 2015 Syngenta.