The Agronomists, Ep 112: Rotten root rots with Alison Robertson and Clint Jurke


Tonight’s episode of The Agronomists is dedicated to those rotten… you guessed it… root rots.

Identification, rotation impacts, scouting tips, and likely culprits for canola, corn, and soybeans — host Lyndsey Smith covers it all.

Joining her is Clint Jurke, of the Canola Council of Canada, and Alison Robertson, of Iowa State University.

This episode of the Agronomists is brought to you by ADAMA Canada, RealAg Radio, and the Canola School!


  • Warm and wet or cold and wet. What’s worse? That’s a tough one. Depends what disease we’re talking about, and if the crop is growing actively
  • If you don’t have the same amount of seeds come up that you planted, there’s a good chance you have a root rot problem
  • 5 degrees C to 15 degrees C is typically the range for pythium
  • Aphanomyces can impact alfalfa! Not just pulses
  • The way corn germinates, the growing point stays under the soil, soybean brings cotyledons above the soil surface and that changes the protection dynamic
  • How long can we count on our seed treatments? Typically around three weeks is what the manufacturers recommend
  • Knowing the different types of the root rots isn’t always important, but from an academic perspective its super important to understand the spread/control options
  • Are all the species equally pathogenic? Nope! Depends on the temperature and host

CLIP 1: Soybean School: The future of soybean genetics for Western Canada

  • Race types and soil types…here we go!
  • Heavier soil types will hold onto moisture longer, making it more susceptible to root rots
  • Do we have resistance in a lot of the lines we rely on?
  • Some diseases are condition specific, and some are host specific
  • A longer rotation in general is a good practice in reducing the level of risk, but it doesn’t solve all of the problems. Some of these spores last for many many years
  • If we’re alternating between corn and soybeans, seed treatments are really going to be the key. And continuing to test for resistance
  • The key is, can we get that crop out of the ground as quick as possible
  • Later on in the season you can find root maggots in canola, and those holes in itself can cause root rots. Everything is connected!
  • Do good agronomy all the way through
  • Where does phytophthera and aphanomyces fit in the spectrum?
  • Jurke has a fantastic graphic about the strains and aggressiveness of root rot
  • There are later season infections…don’t forget about the potential of those
  • It’s not just one pathogen always that causes symptoms in a plant
  • Do cover crops help hinder root rots in tighter rotations? So far, the observation is cereal rye is helping. BUT, again, it all depends
  • Is Alison looking at whether incorporating cover crops would help hinder root rots in tight rotations and and if so, any observations so far?
  • Cover crops can actually make it worse for corn (cereal rye, we mean), but less for soybean
  • Later season diseases that are actually early season diseases…blackleg, verticillium stripe
  • Genetic screening is already happening as far as verticillium is concerned. Seed companies are working very hard to incorporate it in
  • Is a fungicide pass earlier in the season warranted for blackleg? If it’s early enough, yes. It needs to be early — like cotyledon stage

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The Agronomists (view all)Season 4 (2023) Episode 25

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