Pulse School: Scouting for root rots from emergence to flowering

Root rot damage. Photo Credit: Syama Chatterton

After the crop is in and you start to see the fruits, or emergence, of your labour, it’s time to keep a watchful eye out for any stress points to best be able to detect root rot.

On this episode of the Pulse School, Mike Palmier, owner of MaxAg Consulting, goes through when to scout for root rot, how to differentiate the different kinds, and how to best utilize crop rotations to mitigate the onset of root rot in your pulses.

Scouting for root rot doesn’t fall within a small window of time, according to Palmier. Farmers should focus scouting efforts anytime between emergence and flowering when the plant is under stressful conditions. Stress can give the root rot pathogens an opening to infect the plant.

“You will want to look for any root rot after a heavy rainfall, maybe there’s a little bit of water sitting in some low spots or after you spray your herbicide, which will stress that plant out for a period of time,” explains Palmier. “Those types of incidents throughout the year will definitely give openings for the root rots to potentially take over. So the key then is to make sure that you dig up that plant and check out the roots even if you’re not seeing visual symptoms above the ground. The roots will give you an idea on what the future of the above ground matter will be.”

If root rot is present, it’s also important to determine which kind of root rot you are dealing with and Palmier says there are different symptoms, and field conditions, to look for which will help pinpoint the variety.

In areas where it’s been wet and cool, pythium root rot can be more prevalent. In fields with poorer residue management or poor straw spread from the combine, that’s where Palmier says he sees a higher occurrence of fusarium root rot. He says for that specific type, a common symptom is woody roots that are brown and hardened off around the root with a yellowing of the leaves there after.

In some areas, the most talked about variety of root rot is aphanomyces, which Palmier says is quite dependant on moisture levels, therefore, making sure that your field has proper drainage is highly important as he says, sometimes it doesn’t take much to push the rot into full gear.

“Just try to manage your stresses all throughout the year. Because potentially, your pathogen levels are maybe just high enough to cause an issue, that little bit of extra stress could cause it to go over over the edge,” says Palmier.

Unfortunately, there isn’t much that can be done once root rot has established itself, however, through proper crop rotation, it is possible to lessen the chance of it in the pulse crop.

Palmier says it’s not a blanket rule of thumb that determines the optimal crop rotation as some root rots can transfer over to cereal crops quite easily, while others are predominantly found only in pulse crops. Additionally, he says if there is a history of disease, producers should likely look at lengthening the pulse rotation even further to help mitigate the chance of root rot taking ahold in a field once again.

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