The Agronomists, Ep 129: Spot spraying to save money with Tom Wolf and Carl deConinck Smith


It pays to spray — but does it pay to spot spray?

On this episode of The Agronomists, host Lyndsey Smith is joined by Tom Wolf of AgriMetrix and Sprayers 101, and Saskatchewan farmer Carl deConinck Smith for a discussion on spot spraying — where it fits best, when in the year, and how to calculate the true value.

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This episode of The Agronomists is brought to you by ADAMA Canada, Corteva Enlist E3, and RealAg Radio!



  • Fall is in full swing!
  • Green on brown vs. green on green
  • Algorithms on new tech determine what to spray and what not to
  • We need more actives per plant at the same cost or less — this was why deConinck Smith got into spot spraying
  • Without spot spraying, chem fallowing is difficult or uneconomic
  • Use more water without using more water?!
  • A LOT has changed in the sprayer sphere since the last Agritechnica four years ago. Tech that was just in a concept then, is now for sale and in the field. It goes quick
  • Targeting some of these weeds multiple times of year (we see you, kochia)
  • The thinking has changed with some weeds, such as pigweed. “Leave no pigweed behind.” The price of leaving a resistant pigweed behind is way too high
  • Are the spot spraying systems good enough to meet this criteria?
  • The problem with the industry is when we are recommending more expensive tank mixes — we are kicking the problem down the road. Buying time, but not necessarily dealing with the problem.
  • The spot spraying system allows us some more time, because it’s cost effective
  • Time is a cash cost, an opportunity cost.
  • Chem fallow is where you don’t crop anything. Number one reason: storage of moisture. Also used for weed control.
  • These algorithms can think faster than a human. The ability to identify a weed species is incredible and machine specific
  • We’re driving across the fields at 15km/hr finding plants and separating them from weeds, and they are spraying weeds based on a threshold that’s been identified. It’s a revolution!
  • There’s options out there with doing a broadcast spray beside a spot spray
  • How advanced are these algorithms, to be able to detect between weeds and crops that look alike? Like wild mustard vs canola, etc?
  • If we can use green on green, can we use higher rates without crop phytotoxicity? Australia is starting to do this with green on brown, on summer spraying.
  • Is it worth spot spraying if there are subscription fees? There are some costs that we do have to consider.
  • What do we do with the savings from spot spraying? Do we put it in our pockets, or do we re-invest it into our systems?
  • Miss rates, what are they? What do you do when weeds don’t die? A miss is a weed that was not sprayed.
  • What about using a system like swatcams that treat the systems in zones? Wolf is all about the swatcams. It’s a great entry tool to getting into spot spraying.
  • We get maps from these systems which is great to look back on.
  • This dovetails into the conversation of density of the weed population.
  • Spot spraying isn’t for every field on your farm. You have to define what it’s good at, and what it’s not good at.
  • deConinck Smith says from his experience, accuracy is anywhere from 90-95 per cent.

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