Disease management becomes critical in crop protection

Many farmers still see the need for crop disease management as an infrequent, pain-in-the-butt event that is more about defence than offence. But with two consecutive cold, wet and late growing seasons on the prairies that provided ideal conditions for many crop diseases to take hold, that thinking may need to change, says a plant disease specialist with the Saskatchewan Ministry of Agriculture.

“As agronomists, we would like to see farmers making a mental shift to the point where they still view disease as a sporadic event, but one they are prepared for as a regular component of their crop management and may or may not need to use when the time comes,” says Faye Dokken-Bouchard.

Keith Fournier, from Lloydminster, AB, is one producer who has made that change. Like many farmers, Fournier reached the turning point when he lost some canola yield to sclerotinia a few years ago. Since then, the grain, oilseed and pulse producer has started to employ practices such as a pre-seed burnoff as well as scouting prior to seeding and harvesting. But perhaps his most influential decision was to simply look at what successful farmers were doing.

“You just have to look at the farmers that do a really good job of producing a crop, then do what they’re doing,” he says. “They’re the ones who are out scouting. They’re the ones going to farm tours and talking to agronomists at farm meetings.”

Dokken-Bouchard and Fournier offer some tips for producers ready to get more value from their disease management dollar.

Make your scout count

In a perfect world, field scouting would take place several times throughout the growing season. The reality is, sometimes it’s only possible to scout once. The key, says Dokken-Bouchard, is to get as much value out of that one scout as possible.

“If you have time to scout only once then you should be focusing on catching the early signs of disease and identifying the best timing for fungicide application,” she says.
“With pulses, that means looking for early signs of disease prior to flowering or canopy closure. Spray cereals when the flag leaf emerges because the top two leaves of a cereal crop have the greatest influence on yield. For canola, it means looking for sclerotia germination before flowering, and spraying at the 20 to 50 per cent bloom stage.”

Watch the weather

Many crop diseases thrive in wet conditions, so it’s crucial to keep an eye on the weather when deciding when to spray, says Dokken-Bouchard. It’s particularly important for canola crops because by the time you see the symptoms of sclerotinia, it’s already too late to spray. “It’s not so much about symptoms as signs of disease, but about when the crop is going to be flowering and whether there are rainy conditions during that period or not.”

Get a good sample

“Look at different spots throughout the field, not just the headlands and approach,” says Dokken-Bouchard. “Walk a ‘w’ shaped, zigzag pattern so you can get a good assessment of different spots throughout the field. Get down in the canopy, pull plants and look at the roots — you might even want to use a magnifying glass to see if you can see any lesions or fungal structures.”

Look at history

A producer’s own experience with crop diseases can be a key tool in helping to strike down disease threats early. “You need to look at the past history of diseases, when the crop is going to be flowering and whether there have been rainy conditions during those periods,” says Dokken-Bouchard.

Stay in the loop

One key way Fournier improved his crop management practices was by listening to what the experts had to say. “Reading articles in newspapers and magazines helped, as well as staying in contact with grain company agronomists. Going on field tours really helped because the agronomists pointed out what to look for and when to look for it.”

Fournier and some other producers in his area have also set up a grain marketing club that meets once a month during the winter to discuss what worked and what didn’t on their farms during the growing season. “I really think I gain a lot of knowledge just networking with other producers,” he says.

Photo Credit: Genesis Studio