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Soybean cyst nematode confirmation presents challenge for producers

Pests like soybean cyst nematode and clubroot are present and rising in Manitoba fields, but the steps to prevent both of those pests are largely the same

Farmers are being urged to keep equipment clean after the confirmation of yet another soil-borne crop threat in the province.

Farmers got the unfortunate, but not unexpected, news that soybean cyst nematode (SCN) infections have been confirmed in four municipalities Sept. 16. The nematode, which can spread through water, has been present in North Dakota for years and has been expected to spread north through the Red River. This year, however, is the first that researchers noted both symptoms and molecular test confirmation of SCN.

Mario Tenuta, a soil scientist from the University of Manitoba, led the research project that confirmed its presence. He said the pest has likely been in the soil for “a few years” quietly reproducing and multiplying each season soybeans were grown on the fields.

“Every time that soybean is grown, and the pest is there, it will reproduce and increase its numbers by the production of these cysts, and each cyst contains eggs, many eggs, it could be 200 eggs within a cyst,” Tenuta said.

Soybean cyst nematode is the latest, but not only, soil-based issue that farmers are facing. Similar management techniques apply to most of these pests.

Tenuta’s team has been on the watch for the pest since 2012.

The municipalities of Norfolk-Treherne, Rhineland, Emerson-Franklin and Montcalm have all come down with visual symptoms of the pest, although a recent update from Manitoba Agriculture says none of the symptoms are bad enough to cause economic damage.

So far just four rural municipalities have confirmed SCN infections.
photo: Manitoba Agriculture

One field in each of those municipalities has tested positive. A total 106 fields in 18 municipalities were tested through the monitoring program.

With the exception of the municipality of Montcalm, the nematode has cropped up alongside waterways, exactly where Tenuta and his team would have expected to first see signs of SCN.

“Given the large gap between regions with positive identification, there is a possibility that SCN may be present in fields that were not included in the survey, or may have established since sampling of a field has occurred,” the Manitoba Pulse and Soybean Growers said in a release.

Lessons from clubroot?

SCN management echoes what canola growers have already heard, especially in the eight municipalities with confirmed clubroot symptoms or high spore loads.

That disease has been another source of soil-based anxiety for farmers. The swollen root galls caused by the pathogen threaten to starve plants by cutting them off from nutrients and has caused serious issues in heavily infected areas in Alberta.

Earlier this month, Manitoba Agriculture confirmed a new type of clubroot able to break through some resistant varieties of canola in central Manitoba.

“A lot of the practices that we recommend for clubroot or even for some animal pathogens and viruses, anything that can be transferred in soil or survive in soil, we recommend (biosecurity practices),” Tenuta said.

Both SCN and clubroot can last for years in the soil, leading to calls for longer rotations to curb soil populations and to control other weeds that might act as a host — and therefore a bridge — for either pest.

“The greater the time period between successive canola crops, the better,” Manitoba Agriculture canola specialist Dane Froese told Glacier FarmMedia this July. “Lengthening the rotation really helps the spore load decrease in canola fields, as well as reducing the risk for future infection.”

SCN management follows the same rationale. Tenuta also urged producers to consider resistant varieties the next time it comes time to buy seed, echoing canola-focused advice on clubroot.

Cleaning up

Farmers in the middle of the 2019 harvest, however, may be more concerned with clean equipment.

Experts like Tenuta and the Canola Council of Canada are asking farmers to avoid moving soil from one field to another to avoid spreading an infection. Among other suggestions, farmers are being urged to reduce tillage, give more attention to wind conditions if high-disturbance tillage is needed, and to clean equipment in between fields.

That last may be a hard sell for farmers in the crunch of harvest, Tenuta acknowledged.

“They’re in a pinch. They have a lot of territory to cover and to go back to a yard and wash down their implements may be challenging,” he said.

A mobile pressure washer and water tank may go a long way to mitigate that inconvenience, he added.

Tenuta also urged farmers to make sure used equipment is clean and to keep pickups and trucks out of the field. His own team makes a point to park off the field and walk in during their research, always wearing biosecurity booties.

Both clubroot and SCN are more likely to crop up near field entrances where soil from other fields is more likely to fall, both Tenuta and the canola council say. In 2017, an Alberta agronomist with the canola council, Dan Orchard, urged Manitoba farmers to consider a separate exit from the field for that reason.

That may help, Tenuta acknowledged, although he stressed that clean equipment should be the first option to avoid infection spread and that things like a separate exit should be insurance rather than a main strategy.

Future monitoring

Tenuta hopes to see monitoring efforts expand now that the nematode has been confirmed in Manitoba and has, in fact, been found in municipalities already at the edge of their monitoring program. The scientist would like to monitor areas around Beausejour, the northeast, Selkirk and farther west towards Portage la Prairie and even Brandon.

Some of those areas are newer to soybeans than the Red River Valley, he noted, but are now approaching enough history with the crop for SCN loads to grow.

About the author

Reporter

Alexis Stockford is a journalist and photographer with the Manitoba Co-operator. She previously reported with the Morden Times and was news editor of  campus newspaper, The Omega, at Thompson Rivers University in Kamloops, BC. She grew up on a mixed farm near Miami, Man.

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