There are no distinct above-ground symptoms unique to SCN. Since SCN impacts water and nutrient uptake, stunting, chlorosis and necrosis are common symptoms, however, once above-ground symptoms are apparent, up to 30% yield loss may have already occurred. As a result, dig up roots in August to look for cysts and to catch this destructive soil-borne soybean pest early.
Scouting for SCN:
1. Gently dig up soybean roots from late July to August and examine them for cysts. Cysts are smaller than root nodules and appear as white, lemon-shaped cysts on the roots.
- In clay soils, roots may need to be soaked to loosen and remove soil.
- Magnifying lenses may come in handy to take a closer look at roots in the field.
2. Target high-risk areas of the field, which includes anywhere that soil containing SCN could have been introduced. This includes field approaches and headlands, low spots and water runs, shelter belts, high pH areas and any generally low-yielding areas of the field.
3. If you suspect SCN, soil samples can be collected and submitted to Agvise to get an idea of abundance (eggs/100 cc of soil) which can guide management decisions. If samples submitted to Agvise come back positive for SCN, contact MPSG for further testing.
Management strategies include growing SCN-resistant varieties, reducing tillage and controlling host weed species (of which there are more than 110 species). Other crop hosts include dry beans, peas, clovers, and vetches, among others. Once introduced to a field, SCN cannot be eradicated, only managed.
Since SCN is just starting to get established in Manitoba, prevention is still a valuable management tool. SCN is soil-borne, so anything moving soil has the potential to move SCN. Ensure new equipment is free of soil before entering your fields. Clean soil sampling equipment and field tools between farms. It is likely that SCN is lurking undetected in several fields due to previous flooding along the Red River.