When Trying to Identify What’s in Our Fields, Get into Your Field

By Harry Siemens

Chris Manchur kicked off

@stjeanfarmdays with an informative talk on herbicide-resistant weeds in the Red River Valley. Managing weeds like water hemp and kochia properly is a top priority for maintaining yield and product options.

Manchur, an agronomy specialist for the Canola Council of Canada in eastern Manitoba, said plenty of pathogens are hiding in farmers’ fields. Some of the big three in Manitoba would be blackleg, sclerotinia, and Verticillium stripe.

“But really when we’re looking at trying to identify what’s in our fields, you need to get out into your field,” said Manchur. “Take some stubble samples, send those off for testing, and know how to diagnostically assess what’s in your field at those crop stages, especially later on.”

Verticillium stripe is showing up a lot more this past year and is something that farmers need to watch. Verticillium stripe, also known as Verticillium longisporum as its species name compared to Verticillium wilt, also called Verticillium dahliae are in the same family.

“They have some similar symptoms, but specifically stripe affects canola and exhibits those characteristic striping symptoms on the stems,” he said.

In the early ‘90s and before, the industry considered it the same pathogen, but it has evolved to be more genetically distinct. For example, in Canada’s canola it is Verticillium stripe that most likely affects the crop.

Manchur said with the significant problem in 2022 there are some expectations that with the year we had for Verticillium stripe, there is probably more on the microsclerotia, which is formed from over wintering and spreading structures in phytopathogenic fungi in the soil. This provides an opportunity for it to come back again this year.

“But we also must be aware that the environment plays a major role in how that pathogen behaves,” said Manchur. “For example, we have similar conditions like excessive moisture earlier on and hot, dry summers with little precipitation. In that case, there is an increased likelihood we may see a Verticillium stripe return.”

The agronomy specialist cautioned farmers to be aware of scouting their fields to see if the problem was there the year before and know how it will impact the growing crops in the next few years.

To protect themselves farmers can look at potential sources of genetic resistance.

“We know that there is some inherent resistance in our seed varieties grown today compared to, say, seed varieties of yesteryears, which may not have had as much,” he said.

Rotation is always a good option to reduce inoculum load and create a good awareness of what’s in the field so as to have as much information as possible to make decisions.

To get ahead of the problem, the Canola Council is bringing increased awareness for Verticillium stripe, especially in Manitoba and Saskatchewan where it’s also starting to appear.

“We’re trying to give as much information as possible to growers on options for management of that and help promote research and identify priorities within the research community so that we’re investing growers’ dollars into the right things to provide