Symptoms of SCN damage apparent early

decrease font size  Resize text   increase font size       Printer-friendly version of this article Printer-friendly version of this article

click image to zoomFigure 1. Mild yellowing and stunting of plants caused by SCN. As if the direct effects of Iowa’s hot, dry growing season on crops were not damaging enough, the soybean cyst nematode (SCN) probably will be more damaging this year than in the past two decades due to the lingering drought conditions.

Symptoms of damage appearing sooner in 2012

Damage from SCN does not always cause aboveground symptoms, especially in years with adequate to excess moisture. But when symptoms occur, they usually appear in mid to late July (see 2011 ICM News article here). 

This season, stunting and yellowing of soybean foliage caused by SCN feeding has been apparent throughout the state since late June, which is much earlier than usual. 

click image to zoomPhoto by Jim FawcettFigure 2. Severe yellowing of foliage and stunting of plants caused by SCN. Symptoms of SCN damage can be relatively mild when SCN population densities, or numbers, are low (Figure 1). But stunting and foliar yellowing can be severe in very dry soils and when SCN population densities are high (Figure 2). The earlier those symptoms appear in the growing season and the more severe they become, the greater the yield loss that occurs with SCN.

Yield loss with SCN-resistant soybean varieties in 2012

Soybean yield losses from SCN have been minimized over the past 20 years through use of resistant soybean varieties. Good SCN-resistant soybean varieties keep nematode reproduction in check and produce profitable yields in fields infested with the nematode, at least under most conditions.

Almost all SCN-resistant soybean varieties available for the Midwest have resistance genes from a breeding line called PI 88788. Because of repeated exposure to the same type of resistance, many of the SCN populations in Iowa fields have increased reproduction on varieties with PI 88788 SCN resistance genes. 

SCN populations with elevated reproduction on PI 88788 resistance were first noticed in Iowa seven or eight years ago.  But to date, the increased SCN reproduction has not severely reduced yields of resistant varieties or caused large increases in SCN population densities in Iowa. 

Unfortunately, greater yield loss and larger increases in SCN population densities on SCN-resistant soybean varieties are possible for 2012 because root stunting from SCN feeding makes plants even more drought stressed and also, there seems to be greater reproduction of the nematode in dry soils (as discussed in an ICM News article earlier this year).

Management of SCN requires persistence

Successfully managing SCN is not an achievement to be accomplished in one growing season; it is a continual process. To ensure profitable soybean production in SCN-infested fields long-term, a sustained, integrated approach is necessary. 

Every field in Iowa in which soybeans will be grown should be checked for SCN. This can be done by checking roots for SCN females (see ICM News article here) or by collecting soil samples to test for SCN (see ICM News article here). 

Fields that are known to be infested with SCN and have had resistant soybean varieties grown should be sampled periodically to assess SCN population densities. Knowing if SCN population densities are decreasing, increasing or staying the same in a field over a period of six years or so will indicate how aggressive of an approach to management is needed to maintain profitable soybean production in the field in the future.

Growing nonhost corn in alternating years with SCN-resistant soybean varieties is key to keeping SCN numbers from increasing. Growing varieties with various sources of SCN resistance, if possible, reduces the selection of SCN populations with increased reproduction on the very common PI 88788 source of resistance. Finally, there are new nematode-protectant seed treatments that can be used in conjunction with SCN-resistant soybeans for added defense against the nematode.

More information about the biology and management of SCN can be found at and the Plant Health Initiative’s website.

Prev 1 2 Next All

Buyers Guide

Doyle Equipment Manufacturing Co.
Doyle Equipment Manufacturing prides themselves as being “The King of the Rotary’s” with their Direct Drive Rotary Blend Systems. With numerous setup possibilities and sizes, ranging from a  more...
A.J. Sackett Sons & Company
Sackett Blend Towers feature the H.I.M, High Intensity Mixer, the next generation of blending and coating technology which supports Precision Fertilizer Blending®. Its unique design allows  more...
R&R Manufacturing Inc.
The R&R Minuteman Blend System is the original proven performer. Fast, precise blending with a compact foot print. Significantly lower horsepower requirement. Low inload height with large  more...
Junge Control Inc.
Junge Control Inc. creates state-of-the-art product blending and measuring solutions that allow you to totally maximize operating efficiency with amazing accuracy and repeatability, superior  more...
Yargus Manufacturing
The flagship blending system for the Layco product line is the fully automated Layco DW System™. The advanced technology of the Layco DW (Declining Weight) system results in a blending  more...
Yargus Manufacturing
The LAYCOTE™ Automated Coating System provides a new level of coating accuracy for a stand-alone coating system or for coating (impregnating) in an automated blending system. The unique  more...
John Deere
The DN345 Drawn Dry Spreader can carry more than 12 tons of fertilizer and 17.5 tons of lime. Designed to operate at field speeds up to 20 MPH with full loads and the G4 spreader uniformly  more...
Force Unlimited
The Pro-Force is a multi-purpose spreader with a wider apron and steeper sides. Our Pro-Force has the most aggressive 30” spinner on the market, and is capable of spreading higher rates of  more...
BBI Spreaders
MagnaSpread 2 & MagnaSpread 3 — With BBI’s patented multi-bin technology, these spreaders operate multiple hoppers guided by independent, variable-rate technology. These models are built on  more...

Comments (0) Leave a comment 

e-Mail (required)


characters left

Grain Storage Systems

Behlen Grain Storage Systems offers large capacity bins with diameters from 16’ to 157’ and capacities exceeding 1,500,000 bushels. All ... Read More

View all Products in this segment

View All Buyers Guides

Feedback Form
Feedback Form