Lentil growers had a hard time pulling off a good crop in 2016. A wet growing season and damp harvest plagued many farmers.
“Without a doubt there were some good quality lentils produced in 2016, but the percentage of high quality lentils produced would be much lower than what we typically see in Western Canada,” says Trevor Glas, marketing development specialist with Bayer CropScience.
High disease pressure took its toll on lentil quality as well. “White and grey mould were the major culprits this year,” says Glas.
Mother Nature holds all the cards when it comes to weather. But farmers have a few tricks up their sleeves to help them manage disease.
Know your diseases
Glas says there are four major lentil diseases to watch for; ascochyta blight, anthracnose, sclerotinia (white mould), and botrytis (grey mould).
Ascochyta blight can be seed- or residue-borne. Lesions are tan or grey with dark borders, and may have little black spots (fruiting bodies) in the middle, according to the Saskatchewan Pulse Growers.
Lentils infected with anthracnose will have grey to cream coloured lesions on stems and leaves. Lower leaflets will yellow or brown before dropping, and lower stems will canker, killing the plant.
Botrytis (grey mould) shows up as fuzzy grey growth. On young plants, it appears near the soil surface, according to Alberta Pulse Growers. Botrytis grows on pods, flowers, or lower stems on older plants, Alberta Pulse notes.
Lentils with white mould on stems, leaves, pods, and flowers are infected with sclerotinia (white mould). Alberta Pulse notes that the first signs are “light-brown, water-soaked discolourations” on stems, leaves, or pods. A cottony thread will show up around the collar if humidity and temperatures stay high, Alberta Pulse says.
Both botrytis and sclerotinia are late-season diseases. Farmers dealing with grey mould should use dust masks during harvest, as spores can cause breathing problems, according to Sask Pulse.
“It’s all about preventative disease management. In lentils, you cannot wait for disease to show up,” says Glas.
Predicting disease presence is difficult, says Glas. He suggests farmers take a look at their crop when deciding whether to spray. A crop with good or extremely high yield potential is worth protecting, he says.
Cropping history also plays a role.
“Looking at your rotation or your neighbour’s crop rotation can help predict the presence of diseases like sclerotinia, for example,” says Glas. Sclerotinia also hits canola, peas, and sunflowers.
“So if canola’s in your rotation, there’s a very good chance–especially if you’re in a tight rotation — that sclerotinia could be a problem in your lentils,” says Glas. Sask Pulse also recommends a four-year crop rotation to manage anthracnose. And ascochyta blight overwinters on lentil stubble, so Sask Pulse advises farmers to avoid growing lentils on lentil stubble.
Sask Pulse notes that while botrytis inoculum lurks in the soil of every field, it generally only rears its mouldy head when heavy stands lodge during wet, cool summers.
Farmers also need to consider genetic resistance within the variety, stand density, moisture conditions in the soil and crop canopy, and rain forecast, says Glas.
“A single application in lentils is extremely common in the majority of the lentil-growing area,” says Glas. In higher input lentil growing areas, it’s common to apply fungicides twice, he adds.
Usually agronomists recommend applying fungicide at flowering, for the first pass. “But this year, the… vegetative growth was so dense in the lentils that the rows were closing prior to flowering.”
That’s why it’s important to look at row closure as well when timing the first pass, Glas says. Because of the moisture and growing conditions in June, many lentil growers applied fungicide earlier than if they’d looked at flowering alone.
Farmers trying to prevent late-season diseases such as sclerotinia or botrytis will spray again 10 to 14 days later, Glas says.
Sclerotinia and botrytis are challenging diseases to manage, partly because farmers need to apply fungicides before the disease shows up.
“If you wait for the disease to show up, it’s too late and the damage is going to be done. You’ll get some control but it’s not going to be satisfactory,” says Glas. Farmers who applied fungicide before row closure, and did a second pass later, saw better yields and quality, says Glas.
But getting the second pass right is tricky with botrytis and sclerotinia. “When you make that second application you’re really trying to drive the fungicide down into the canopy,” says Glas. That can be difficult, he says, especially in a year like 2016 when the canopies are very dense.
To improve coverage, Glas suggests making sure boom height is set to 18 to 20 inches above the target. Higher water volumes also help. Glas says 10 gallons of water is the minimum with a ground application. But growers will apply up to 15 gallons of water to push more spray solution down into the canopy. Slowing down also helps.
Farmers should also double check the labels for rates, and to make sure the product is registered for the diseases they’re planning to hit. Glas says Bayer’s product, Delaro, does provide protection for all the major lentil diseases, but not all fungicides do.
Environmental conditions are important, too. Avoid windy days, Glas says. And he doesn’t recommend spraying in extreme heat — 30 C or higher. Glas adds that the closer the mercury gets to 30 C, the more water is needed.