Wheat Pete's Word, June 27: Leaf burn, lodged wheat, and thrips in corn


Ontario has turned into the land of extremes, where wet areas are suffering through excessive rainfall when it happens, while other areas wither in the dry and the heat. There is one near-perfect area — the Ottawa Valley — and host Peter Johnson figures it’s so perfect out that way, he doesn’t have to answer any of Lyndsey Smith’s questions.

This week’s edition of Wheat Pete’s Word does feature a decent list of issues in other parts of the province, though — from a surprising amount of damage from thrips in corn, to the yield impact of fertilizer burn, and on to how to tell pigweed from waterhemp (and why it matters).

Have a question you’d like Johnson to address? Or some yield results to send in? Leave him a message at 1-888-746-3311, send him a tweet (@wheatpete), or email him at [email protected].


  • Relay intercrop soybeans at Lucan update: 3″ of rain didn’t even fill the cracks. The soybean plants standing back up, but probably lost 10% of the stand
  • 2″ of rain fell and nothing in the tile? That’s because the soy and edible beans sucked it right up!
  • Check your catch basins and inlets, make sure to keep ’em open (in the spring too!)
  • Scouting checklist for this week: Armyworm in winter wheat — don’t worry, it’s too late for it to cause significant damage, unless they’re clipping heads. Reports of soybean aphids at Milton and Bruce County, it’s not confirmed but start looking! Can cause significant damage, but remember the threshold of 250 per plant and rapidly increasing
  • Thrips have been found in the corn crop near Seaforth. With five to seven weeks of little moisture in the rapid growth stage, everything becomes an added stress. No real threshold for thrips in corn. Stippling on leaves could cause yield loss, so keep scouting
  • Waterhemp has been confirmed resistant to 4 different modes of action. If you think you have pigweed escapes, it could be waterhemp. No hairs on the underside of the leaves means it’s waterhemp and almost for sure it’s resistant to one or more groups of herbicide
  •  Fleabane in the ditches needs controlled. Don’t use glyphosate!
  • Lodged wheat is a variety thing, but also we’re seeing root lodging — where high winds and heavy rain in some areas have pulled leaves and is too much pull on the root system
  • Corn nitrogen: Excess rain = lost N, higher top dress needed. Dried out? You’ll need less Sometimes surprisingly low amounts. Read more here.
  • Streamed 28% on 6-8 leaf corn and are seeing burning as the whorl grows out? Is there yield loss? In trials, v4 to v5 corn (7 leaf-ish) yield impact is  almost zero, but 8 to 9 leaf corn, you will see yield loss from leaf burn
  • Agrotain with 28%, will I see more burn? No data to say yes, so there are likely other factors at play. Did I lose a lot of N with burn? You lose it off the soil, not off the leaves
  • When should you top dress with ESN to release at tassel timing? It’s temperature and moisture driven. So it’s pretty hard to guess pinpoint. Give it at least a month
  • 1 gallon of UAN at anthesis? Pete’s answer: Why? And don’t you dare put it on with fungicide!
  • Fungicide on soybeans: Above 28 degrees C, white mould won’t sporulate. You need two sprays to protect, the first at R1.5 (could be this weekend for the earliest fields)

Wake up with RealAgriculture

Subscribe to our daily newsletters to keep you up-to-date with our latest coverage every morning.

Wake up with RealAgriculture

Other Episodes

Wheat Pete's Word (view all)Season 4 (2018) Episode 26

Please register to read and comment.


Register for a RealAgriculture account to manage your Shortcut menu instead of the default.