If you have any fields that were in soybeans in 2012 that you intend to plant to beans in 2014, listen up! "Fields that grew soybeans in 2012 that had soybean cyst nematode infestations in the soil saw extremely high reproduction that year," says Clarke McGrath, an Iowa State University Extension field agronomist. "That was true even if SCN resistant soybean varieties were planted in those fields. If susceptible soybean varieties are grown in those same fields this year, the SCN population will likely increase significantly. SCN damage to soybean yields this year could be pretty ugly."
He suggests you click on this link to ISU Extension nematologist Greg Tylka's recommendations for managing this pest and read what Tylka has to say about the SCN threat for 2014.
Some farmers have had their soil tested for SCN eggs this spring to see the size of the overwintering population, says McGrath. "That information can tell you if you need to plant soybean varieties that are resistant to SCN along with using a seed treatment nematicide. If you haven't tested your soil yet for SCN in these suspect fields this spring, you still have time if you sample the soil and get it to a testing lab quickly."
Should you switch to an SCN resistant bean variety?
What if you run out of time to test, or want to try to switch soybean varieties now (prior to soil testing for SCN)? Some farmers want to switch soybean varieties now rather than waiting and risking not being able to get the particular variety they want. "I say go ahead and switch to an SCN resistant variety," says McGrath. "SCN resistant soybean genetics are top of the line; they are available in good yielding soybean varieties nowadays, so there really isn't a penalty for planting SCN resistant soybeans if you aren't sure whether or not you have SCN infestations in your fields."
He offers this advice, "Protect yourself from SCN by planting SCN-resistant soybeans this spring if you are in a field situation that is at risk. Then sample your soil on a regular basis in the future so you know what you have in each field for SCN population."
SCN can cause extensive damage, limit profit potential
The record low temperatures over the past winter may reduce some pest populations this spring, but university experts and seed company agronomists predict SCN will still threaten yields. "Many growers hope the cold weather we've had in recent months will help decrease pest populations," notes Dale Ireland, seed treatment technical product lead at Syngenta. "But it doesn't affect SCN."
He agrees that "unusually large numbers of SCN may infest fields where soybeans were grown in 2012—a year when SCN reproduction was particularly high. Those fields were planted to corn in 2013, and in most cases will be rotated back to beans in 2014. "The number of SCN eggs in the soil at the time of planting soybeans contributes significantly to the degree of damage and yield loss to SCN. With an overwintering survival rate of nearly 100%, the potential for damage in 2014 is great," says Ireland.
SCN can reduce yield by 20% to 30%, even when soybean plants appear green, healthy and have no visible symptoms. Soil testing is the best way to determine if SCN is present. To help manage and reduce SCN populations in SCN-infested fields, ISU's Greg Tylka suggests rotating crops, planting SCN-resistant bean varieties and using appropriate seed treatments.
New seed treatment promises season-long protection
Ireland agrees with that advice from the ISU specialists. "Choosing a variety with high-yield potential and good nematode tolerance along with a nematicide seed treatment is vital to managing SCN," he says.
Ireland says Syngenta is offering a new seed treatment this year: Clariva Complete Beans is a nematicide/insecticide/fungicide, an on-seed application of separately registered products. It adds a new nematicide to the broad-spectrum CruiserMaxx Beans with Vibrance insecticide/fungicide seed treatment, to provide effective protection against SCN throughout the season, on top of broad-spectrum defense against early-season insects and diseases. "Clariva Complete Beans is specifically tailored to Midwest growers who are battling SCN in their fields," says Ireland. "With Clariva Complete Beans protecting each high-value seed from day one, soybeans have a better opportunity to maximize performance and reach their true yield potential."
"Clariva Complete Beans offers season-long protection against SCN by reducing nematode activity and damage with Pasteuria nishizawae (P. nishizawae), the nematicide active ingredient," Ireland adds. "The treated seed is covered with millions of P. nishizawae spores that colonize and attach to the nematode, ultimately killing it." Click on the video animation, "The stages of Pasteuria nishizawae," at www.farmassist.com which shows how the nematicide in Clariva Complete Beans protects soybeans from SCN. This process occurs in five stages, with the P. nishizawae spores remaining in the soil and repeating the cycle, leading to a drastic decline in pressure so you can grow more soybeans.