How Much SCN Tax Will You Be Paying This Year?

You are planting more soybeans this year for revenue purposes, but just like sharing some of that revenue with the IRS, you’ll be paying a share of your income to the SCN tax. The SCN tax is widely collected from Cornbelt farmers, and only 26% of Iowa Farmers and 18% of Illinois farmers are exempt from the SCN tax. And for those who have to pay it, the tax rate can be as high as 40% without any indication that you have ever paid the tax.

Of course, the loss of revenue from soybeans is not from an SCN tax, but from Soybean Cyst Nematodes which do deduct revenue, without providing any type of tax deduction. Your job as a producer is to maximize your soybean productivity by managing SCN says Iowa State plant pathologist Greg Tylka in his presentation at the 2008 University of Illinois Crop Protection Technology Conference, “For all practical purposes, SCN can never be eliminated from a field once it is present. However, there are things that can be done to manage the nematode in order to maximize soybean yields and minimize reproduction of the nematode.”

Tylka says you have 3 ways to keep money in your pocket, instead of letting SCN rob your bank account.

1) SCN resistant soybean varieties are one alternative, but even they will suffer a 10% yield loss. (That is still better than 30% losses.) And one of the benefits may be in their suppression of SCN reproduction. Tylka offered several test plot examples in which resistant varieties outyielded susceptible varieties by 15 bushels or more; however the number of SCN eggs in soil samples were ten to twelve times greater in the susceptible varieties.

2) A second alternative in SCN management is the use of varieties that have genetics from PI88788, which is the granddaddy for resistant soybean varieties. But, sadly, an increasing number of SCN populations tested around the Cornbelt have shown the ability to reproduce on the PI88788 legacy varieties. For example, 34% of Illinois SCN populations had greater than 10% reproduction. 60% of Missouri populations had greater than 10% reproduction. And a similar story comes from Iowa, but Tylka says, “Most of the resistant varieties usually yielded greater than the susceptible varieties at these locations.”

3) Thirdly, Tylka says SCN management includes the consideration of non-host crops, including corn, small grains, and some other legumes. Their use can cut SCN population as much as 50% in the first year after soybeans. However, the rate of population decline diminishes in successive years.

Summary: Soybean cyst nematode can have a debilitating impact on soybean yield where producers have not been concerned about obtaining SCN soil tests and taking measures to plant either resistant varieties or non-host crops. While nearly every soybean variety, resistant or not, will allow some degree of SCN reproduction, the resistant varieties will suppress SCN reproduction as much as ten fold. Producers who use good SCN management will rotate resistant varieties with non-host crops.