Scouting for SCN – Time to Get Digging

Jun 03, 2020

By Greg Tylka

Iowa’s early planting season means that pests like the soybean cyst nematode (SCN) also are off to a quick start this year, which could result in a greater risk of severe damage from SCN throughout the growing season. This nematode is a major yield-reducing pathogen of soybean and is widespread across Iowa and other Midwestern states. Research conducted in recent years indicates that many fields have not been checked for SCN.

Quick and cheap check for SCN

One of the easiest and cheapest ways to check a field for the presence of SCN is to dig soybean roots with a spade, shake the soil from the roots, and look for small, white, round objects on the roots. These objects are SCN females and each one contains 200 or more eggs. As shown in the figure below, SCN females are much smaller and lighter in color than the nitrogen-fixing nodules that form on healthy soybean roots.

Checking soybean roots in this manner also is a quick and easy way to gauge whether a resistant variety is effectively controlling SCN. Only a few SCN females should be seen on the roots if resistance is working effectively. But if the SCN population present in a field has built up virulence on the resistance genes in the soybean variety, there will be many SCN females present (as shown in the image immediately below).

SCN visible on roots dug through mid August

The SCN females fade from white to yellow, then become tan and eventually brown within a few days to a week as the female dies and the body wall hardens to form a cyst around the eggs within. It is almost impossible to see brown SCN cysts on soybean roots dug from a field with the unaided eye. Some white adult females should be apparent on roots of soybeans growing in SCN-infested soil no matter when the roots are dug.

Fields can be checked for SCN by carefully digging and observing roots through June, July, and into mid August. In warm summer soils, SCN can complete a generation in four weeks, ending with formation of new females on roots. The newly formed SCN females occur on younger roots and as the season progresses, those new roots are forming deeper in the soil and father from the stem of the plant. Therefore, it is advised to dig deeper for roots in July and August to look for SCN females.

Source : iastate.edu

Video: Seeing the Whole Season: How Continuous Crop Modeling Is Changing Breeding

Plant breeding has long been shaped by snapshots. A walk through a plot. A single set of notes. A yield check at the end of the season. But crops do not grow in moments. They change every day.

In this conversation, Gary Nijak of AerialPLOT explains how continuous crop modeling is changing the way breeders see, measure, and select plants by capturing growth, stress, and recovery across the entire season, not just at isolated points in time.

Nijak breaks down why point-in-time observations can miss critical performance signals, how repeated, season-long data collection removes the human bottleneck in breeding, and what becomes possible when every plot is treated as a living data set. He also explores how continuous modeling allows breeding programs to move beyond vague descriptors and toward measurable, repeatable insights that connect directly to on-farm outcomes.

This conversation explores:

• What continuous crop modeling is and how it works

• Why traditional field observations fall short over a full growing season

• How scale and repeated measurement change breeding decisions

• What “digital twins” of plots mean for selection and performance

• Why data, not hardware, is driving the next shift in breeding innovation As data-driven breeding moves from research into real-world programs, this discussion offers a clear look at how seeing the whole season is reshaping value for breeders, seed companies, and farmers, and why this may be only the beginning.