Wheat Pete’s Word, Aug 2: Corn fungicide timing, leafhopper trouble, and N in dairy manure

Wheat Pete finally gets some sweet corn (Supplied, 2023)

Green silks are slow to show up in some areas of Ontario — what gives?

It’s early August and most of the corn should be tasseled by now, but July weather just didn’t push the crop as far ahead as is expected, explains host Peter “Wheat Pete” Johnson in this week’s Wheat Pete’s Word.

Why late tasseling matters, why controlling leaf hoppers matters, and why fungicide timing on corn might need to be pushed later than usual is all on the list for this early August episode.

Have a question you’d like Wheat Pete to address or some field results to send in? Agree/disagree with something he’s said? Leave him a message at 1-888-746-3311, send him a tweet (@wheatpete), or email him at [email protected].


  • You can do better, Peter. Ha! Tony was just kidding. Keep the feedback coming!
  • Salford got the corn for Pete
  • University of Guelph Weeds Team did GREAT. Read more here. 
  • The wheat crop gets a breather this week on the Word (but get it out of the field, please)
  • Let’s talk the real king: Corn
  • The corn is slooooow
  • July heat accumulation was average. 65 CHU behind the 40+ year average
  • About 3 days, on paper, but not what we’re seeing in the field
  • Tassels are finally all emerged for most, but seems 7 to 10 days behind for Ontario
  • The west is ahead
  • Late start to corn spraying
  • If corn doesn’t tassel until Aug 1, add 60 days — black layer is about Oct 1, which is quite late for development to end. And variability plays here too
  • Day length: we lose 5 per cent of sunlight hours in August. September to October, it’s 13 per cent!
  • Biomass drives yield, yes, but it’s the heat and the energy from the sun that fills those kernels and if those last two weeks are in September…
  • New thoughts on corn. Late cobs have the most gibberella, typically. Can have 300x more toxin (DON) than early emerging plants/cobs
  • No green silk? No gib control
  • Applying fungicide at early green silks gives best control but we miss the late emergers from gib, and they will be the source of gib
  • It could be a big gib year
  • Does that mean wait until the END of green silks. Day 5 to 7, not Day 2 or 3 of green silks
  • Hit the majority of the crop, too
  • What about silage? High plant pops push stress regardless
  • Protect the crop, and then get the crop out of the field
  • Does an earlier hybrid make more sense?
  • Critical thinking on nodulation
  • Foliar fungicides don’t kill nodules
  • Soybeans are starting to recover from the wet roots
  • Aphids! Not a wreck this year, but is there product? Sefina is in tight supply or out. But there are other products. We’re getting late enough that a second spray is unlikely
  • ALERT! There are still extremely high potato leaf hopper levels in alfalfa
  • If you don’t control leaf hopper in new seedings, you will reduce the longevity of the stands
  • Don’t let ragweed and foxtail go to seed!
  • Have it once, fight it for years
  • Dairy manure: 8 to 21 pound of N per 1,000 gallons. But it’s not that simple
  • Dry manure only has a few pounds per tonne
  • Winter canola seed needs ordered early (June!). It’s turning heads in Ontario

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