The Agronomists, Ep 38: Tammy Jones and Rob Miller talk pre- and post-harvest weed control

(Kara Oosterhuis/RealAgriculture)

It’s evolving into a rather odd year for pre-harvest weed control in parts of Western Canada as a return of some moisture has meant sprouting swaths, and monster weeds. In Ontario, an accelerated season means plenty of farmers are making the dry-down decision on edible beans this week.

From pre-harvest weed control, to swapping to a desiccant, and on to post-harvest decisions, this episode of The Agronomists gets answers from Rob Miller, with BASF, and Tammy Jones, of Corteva.

Catch a new episode of The Agronomists every Monday night at 8 pm E!

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  • We get a crop update from both Miller (near Guelph, Ont.) and Jones (near Carman, Man.)
  • To spray or not to spray? Desiccant, that is. If you’re thinking in terms of your edible beans, check out our latest Edible Bean School episode
  • Canola sprouting in the pod? Swathed canola re-flowering? We have expletives for that
  • Clip #1: Soybean School: Pre-harvest burndown options for a fast-moving crop
  • Check with your processor for allowed product use
  • The difference between dry-down (desiccant) versus weed control
  • Spraying a four foot tall weed right now is not weed management, it’s now considered dry-down
  • Are there a lot of “escaped” weeds? Consider that they might be resistant
  • The debate to leave glyphosate in the tank mix
  • Pre-harvest interval — go with the herbicide in the tank mix with the longest PHI
  • PHI for canola: time between spraying and cutting, not spraying and putting it in the bin
  • Clip #2: Wheat School: Making the right choice for fall weed control
  • Don’t rely solely on spring control, a pre-harvest pass is a good idea in some circumstances
  • Winter annuals? Weeds that can germinate in the fall?
  • The fall window can be a great way to get ahead of spring — lots of opportunities, but challenges as well
  • Winter does take care of some weeds for us, but some thrive and need that vernalization
  • Some weeds become a small target for herbicide after the combine goes through
  • Even spread of chaff matters; use open falls wisely
  • When to spray out regrowth versus just leaving it for the frost, especially in a year when moisture is limited
  • Snirt (snow plus dirt) is not good
  • Bare soil is undesirable, so consider planting something (if you’re in the east), Miller recommends oats
  • Kochia after harvest, regrowth, seed production… Go Jones Go
  • Grazing? Watch out for nitrates
  • Kochia seed doesn’t last in the seedbank for very long, most of it germinates the next year. Lamb’s-quarters of redroot pigweed, or even waterhemp, have more durable seed coats
  • Back to frost for a second, it depends on the weed
  • Clip #3, which we didn’t actually get to during the show: Weed control in a dry year and the risk of carryover
  • Herbicide carryover: rainfall in-season plus soil texture (clay particles will bind pesticide molecules, higher OM means higher microbial biomass, which process said pesticide molecules)