Wheat Pete's Word, June 24: Dissolved urea, clover credits, leaf burn, and a carryover alert


The longest day of the year has come and gone and we are heading into the thick of summer crop-growing weather. With the heat (and in some cases downpours!) come the agronomy questions and Peter “Wheat Pete” Johnson is ready to answer whatever it is you can throw at him.

In this week’s Wheat Pete’s Word, Johnson tackles a few alerts — herbicide carryover for example — and on to nitrogen credits, a rotation’s value, and how to make your own dissolved urea to top up this wheat crop.


  • Feast or famine? Rainfall has been near perfect in some areas of Ontario
  • Some lovely looking crops, some far less so, depending on where you farm in the province, but overall crops are looking good
  • A few problem areas in both Western Canada and Eastern Canada
  • Weather has been a little whacky, with extreme heat in Ontario, and in Drumheller, Alta., one listener sent in an image of a lovely crop, but on June 19, night temp got down to 2 degrees C!
  • In south Lambton County, big rain events are leading to crusting issues. With four inches of rain in a few hours — that beans on bean ground needs replanting. Because you need rotation, guys. Soil structure pays.
  • Also in Lambton County, wheat crop on an old pasture field, but great soil structure and heavy clay, but it’s lodging.
  • Johnson’s corn got 8/10″ of rain on Father’s Day, and he’s starting to see the sins of planting (it was too wet, causing compaction on the headlands).
  • Revenge sprayer in corn and damp/wet spots last year — corn is ragged this year.
  • Dry last year in the growing season, so we are seeing some Group 27 herbicide injury in edible bean crop from carryover. Peterborough and Wingham areas.
  • Knee-high by the first of July? It’s supposed to be knee-high by the FOURTH of July, and it’s supposed to be up to your knee while on your horse, because it’s your last pass to inter-row cultivate (with horses).
  • First of July? It might make it!
  • Yellow leaves in corn? Rapid growth syndrome. Some varieties are worse than others. And usually indicative of wild swings in temp and when conditions are really good for growth and it’s growing like a weed. Usually not a big impact on yield. Give it a few days, and the green comes back.
  • Alert! Alert! Alert! Rust in the oat crop at Peterborough. Crown rust! You can’t grow oats in southwestern Ontario if you’re not going to use a fungicide. Other areas, you might be fine. Without a fungicide? 20 bushels and 20 pound bushels. Huge issue.
  • Last N app, went over with ammonium nitrate, in warm, dry conditions, and by Monday, burn was showing up on emerging leaves. What happened? Dry product can’t have dust! The dust accumulates in the whorl and damages the emerging leaves.
  • Does that leaf burn lead to yield reduction? It’s all about how much leaf material intercepts sunlight above the cob, not below. So, it shouldn’t have a huge impact.
  • Red clover overwintered, took a cut this spring, planted back to corn and manured it. Can I count on N from the clover? Well, as hay, you took about a third of the N. So 50 pound credit to the corn crop this year, but it’ll be August, ish. So make sure you have early N on there. Manure may help, but not if it’s straw-heavy.
  • Take-all in the wheat crop? It happens in clumps of the field. Usually in early planted wheat.
  • Armyworm, aphids, take-all — how much can the wheat crop take? Have faith!
  • Wheat after oats? Yes! Watch for fusarium, but lower risk than you might think.
  • Volunteer oats could be an issue
  • Dissolved urea on wheat — we’ve got good wheat coming, which could drag down protein. Do we use dissolved urea to try and keep that protein up? Apply after anthesis (10 days after the head emerges). You’ll make more yield! Stream it on. 16 per cent, 1.5 pounds/gallon. Means 20 gallons is 30 pounds of N. Read more: Making Dissolved Urea on Farm.

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