Apply fungicide when lentils start flowering

If you have valuable lentils out in your field, make sure you protect them from crop disease

Spray on time — don’t wait to see signs of disease.

This is the advice Bobbie Bratrud, who farms near Weyburn, Sask., offers to first-time lentil growers.

“Because they’re so valuable this year my advice would be to spray on time, and don’t wait to look for the disease. If you’re starting to see signs of the disease you’ve lost yield potential already,” she says.

This year, the Bratruds seeded 2,000 acres of CDC Dazil CL red lentils, alongside canola, wheat, barley and soybeans. Over the last couple of years, they’ve had issues with ascochyta blight and anthracnose in their area, depending on the weather.

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lentils in a bowl

“Our approach for fungicide in lentils is that we generally plan on spraying. We try to do this at the first flower just before the rows close up,” she says. The Bratruds use Priaxor, and effectiveness lasts about seven to 14 days.

According to Dale Risula, the provincial specialist in special crops for Saskatchewan, the three most typical diseases of lentil are ascochyta blight, anthracnose and stemphylium blight. Lesser diseases include sclerotinia and botrytis.

All five diseases are dependent on moisture and can be controlled with timely fungicide applications. So far, Saskatchewan hasn’t seen much rain, but regardless, farmers have to plan for the worst-case scenario. “You want to be prepared for any potential problems that might come up. It’s not an easy decision to make with regard to controlling disease,” says Risula.

But overuse of fungicides means the risk of creating resistance. “You don’t want to use anything and risk creating insensitivity among disease organisms, but you want to protect your plants at the same time. It’s a matter of field scouting, knowing your history, and choosing the right products,” he says.

Clean seed

Risula says disease management starts with buying clean seed, but this might not have been an option for some growers this year as demand has skyrocketed.

“Some seed treatments can affect spores on the seed if you can’t obtain clean seed,” he says. “In some years this is an issue, when the demand is high, and lentil demand this year is super high with a lot of acres going in.”

He says disease pressure is more likely to be a problem on fields that have been seeded to lentil for multiple years running, and treated with the same modes of action. “If they’re overused, you’re creating more and more multiplications of the disease, and there are so many possible outcomes of disease that can come from each generation because they morph so rapidly and can change and become more aggressive,” says Risula.

He echoes Bratrud in recommending spraying at early flowering, on average the third week of June. However, he cautions growers that spraying without signs of disease can be costly and unnecessary.

“If you’re scouting and there’s an absence of any signs of disease and you’re watching the weather forecast, if it’s wet and rainy and the forecast is calling for more rain, the probability is that you’ll have disease. If the forecast is dry, you’re wasting dollars on fungicide,” he says.

If growers are using resistant cultivars and spot just a few lesions, and the weather is shaping up to be wet, “you’re not taking that big of a risk by not applying fungicide,” Risula says.

As far as fungicide application goes, Risula recommends spraying using adequate water volumes, depending on the crop stand and thickness of the canopy. “If it’s really dense and a heavy canopy, apply using a higher water volume to ensure you penetrate the canopy and get better coverage,” he says.

“Chances are you won’t have that heavy of a canopy, but even so having adequate water volume will ensure better coverage.” †

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Julienne Isaacs

Julienne Isaacs is a Winnipeg-based freelance writer and editor. Contact her at [email protected]

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