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Researchers Are Looking At The Potential For Intercropping When Dealing With Group 11 Resistance To Anthracnose In Lentils

Written by Staff Thursday, Jan 27 2022, 1:00 PM

Anthracnose in Lentils is considered to be one of the most important foliar diseases for the crop.

In 2019, the level of anthracnose was historically high in Saskatchewan, with just over 90% prevalence.

Dr Michelle Hubbard, a Research Scientist with Agriculture and Agri-Food Canada, says symptoms of the disease typically start low in the canopy, and can include stem lesions, as well as water soaked lesions on the leaves.

“As it moves up the canopy, it can lead to leaf drop. And if the symptoms become severe enough and actually girdle the stem. Meaning they wrap up all the way around the stem, they can cause lodging as the stem might break, or nutrient supply could be cut off to the upper part of the plant.”

The anthracnose lifecycle involves survival of pathogen inoculum, or the spores, from year to year and can involve two different races.

She notes environment can have a big impact and encourages producers to be actively scouting for the disease.

“Once the spores are present, and lentils are present to be infected, infection can spread from plant to plant multiple times over the growing season by wind or rain, spreading the inoculum from one plant to another.”

In terms of management options for Anthracnose, fungicides are important, as is crop rotation – not growing lentils multiple times within four years.

Hubbard notes there are also lentil varieties with genetic resistance to anthracnose, but cautions it’s not a silver bullet.

“The resistance is only against the less common, and less virile disease causing race one. So even if you choose a resistant variety, you’re still at risk.”

She says if you do decide to spray, it’s important to do it early as a preventative spray, and before the canopy closes around flowering.

“This resistance is only against the less common and less virile disease causing race one. So even if you choose a resistant variety, you’re still at risk. Other strategies could include doing what you can to avoid a very dense canopy. So not planting too densely. And something that I think may have potential is intercropping. I say “may” because intercropping can help with some other foliar diseases, but there’s really no research as yet on its impact in lentil.”

Fungicides are a very important tool that is commonly used for managing the disease, they can act in many ways and are classified based on their active ingredients.

She says Group 11’s are the most prevalent, followed by Group 7’s, then Group 3’s while other options include M5’s or M3’s.

When using fungicides it’s important to think about the risk for resistance developing as certain ones are more at risk of developing resistance than others.

“Group 11’s are at the highest risk, in part because there’s just a single mutation. So one change in one base in DNA can lead to pretty much total resistance to this group. And then Group 3’s and Group 7’s are medium risk, and then the contact based M5 and M3 group are at a lower risk.”

A survey of by BASF in Saskatchewan showed that a number of lentil fields actually had Group 11 resistance to anthracnose.

Hubbard says given the research, as a grower, you might want to assume you do have insensitivity to Group 11.

“If you consider using fungicides that don’t have a Group 11 active, definitely don’t do two applications of fungicide that contain a Group 11 within a single season. If you apply a fungicide, do it early before canopy closure and keep track of what you’ve done. Use good crop rotations, do what you can otherwise to maintain a healthy crop in terms of weed control and fertility etc. Consider trying intercropping, though I would advise starting small if you’re new to it.”

Michelle Hubbard is a Pulse Pathologist at AAFC’s Swift Current Research and Development Centre and is putting together another survey on fungicide insensitivity in anthracnose of lentils, and the potential use of intercropping in 2022.

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