The Fight Against Soybean Cyst Nematodes

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Article by Anderson Fenton
Crop Sales Specialist
AGRIS Co-operative - THAMESVILLE

Across Ontario, we are observing rising numbers of Soybean Cyst Nematodes (SCN) in the past few years. Soybean varieties that contain the PI88788 trait are no longer showing the same resistance to SCN. This trait has been used in majority of soybean varieties for over 15 years.

Seed companies have been introducing the Peking trait in their breeding programs lately as an alternative source of resistance management. With increasing populations, we are now seeing a higher number of affected fields with more yield loss.

Continuous soybean crops have evolved and increased SCN populations while detouring the resistant trait. Yield loss can be over 30% once a field is infected with the pest. The feeding and reproduction put constraints on the nutrients and water intake of the plant.

Corn and Wheat are not hosts for the nematodes, but they can overwinter in the soil and wait to feed on the next crop of soybeans. At the same time, dry beans can also be hosts for the nematodes. Once a field has been infected it is permanent, so managing to minimize the population is key.

Typically, we begin to notice SCN in stressed areas of the fields when we see some patches of yellowing. SCN can be in your field long before visible damage is done. Loam soils tend to be most favourable for reproduction but can still see high populations in heavy clay soils. High pH levels also seem to be a factor for egg counts For reducing and managing SCN there are a few things you can do.

Crop Rotation

The nematodes can overwinter but when soybeans or dry beans are not grown in the field, populations can be reduced. Rotating soybean varieties also helps.

Scouting/Soil Testing

Carefully digging up the roots of soybean plants and submitting a sample to a soil lab to count the number of nematodes is a good management strategy. The fall is a good time to take samples before harvest. Once you have a test you can establish a baseline population that you can use to monitor your fields to see if numbers are increasing or decreasing.

Seed-applied Nematode Protectants

Seed treatments such as ILEVO and Saltro are both very good options to suppress SCN, something to consider when ordering seed. Reach out to your local Crop Sales Specialist to have your field accessed and manage your risk.