Wheat Pete's Word, May 24: Insect alerts, head snag, and delayed corn strategies


As corn planting moves along in Ontario, the list of issues to deal with in the field is also progressing, as RealAg agronomist Peter Johnson has a pair of insect alerts on this week’s Word.

Unfortunately there’s also been some frost in parts of the country, and Wheat Pete walks us through how to assess the impact of freezing temps, as well as herbicide injury. Is it time to switch to earlier corn maturities? When’s the best time to topdress nitrogen on winter wheat? Also — have you made sure sulphur deficiency doesn’t hold back your wheat? Wheat Pete answers your questions on all these topics and more in this week’s agronomy update!

Don’t forget to send Peter your questions and comments for next week! Leave a message at 1-888-746-3311, send him a tweet (@wheatpete), or email him at [email protected].


  • First of all, harvesting canola in May and still getting 36 bu/ac — incredible!
  • Alfalfa weevil beating up alfalfa in the Niagara region. Threshold? 1 larva per stem if the alfalfa is less than 12 inches tall. 2 larvae per stem on under 16 inch alfalfa. And if you have 3 or more, you should probably spray, as long as you can’t harvest. Some has already been harvested in Oxford County, but too wet to harvest in many places.
  • Cereal leaf beetle — Parasitic wasp controls cereal leaf beetle, however in sandy areas, that parasitic wasp cannot over-winter as well, so those are traditional cereal leaf beetle areas. Threshold is 1 per stem average. Early is better for control. Might be able to tank mix with fusarium fungicide.
  • Frost in Saskatchewan — as low as -7 and below 0 for eight hours. How will winter wheat yield potential be affected? It might drop a tiller or two, but yield impact will be minimal if head is okay. Yield comes from the upper leaves. Also some frost injury in cereal rye in Ontario.
  • Head snag showing up in Branson wheat. Does it matter?
  • Sulphur deficiency will hurt your yield! See “Wheat School: Higher Yield Potential Requires More Sulphur
  • Burnt leaf tips from Buctril — likely looks worse than it is.
  • When’s the best time to apply 28-0-0 on wheat? Question from Montana. The later you put the nitrogen on, the more it apportions to protein and less to yield. Most research says put 30lbs on after anthesis. Mix 50/50 with water to reduce burn. (see more here and here.)
  • Weed control — soybeans are planted, but not sprayed yet. Don’t apply Sencor after soybeans are past hook stage.
  • Conventional corn planted into old hay field. How late to spray glyphosate? Peter Sikkema’s research shows if glyphosate is applied on conventional corn when it’s starting to push soil up, you can have all sorts of issues. If the only weed you’re after is alfalfa, try 2-4D or another herbicide?
  • Horsetail appears to be the weed of the year in eastern Ontario. What’s best herbicide in corn and soybeans?
  • If you don’t have corn planted, it’s now time to start thinking about changing varieties. Take off 100 to 150 CHUs per week from here on in.
  • Consider rotational implications if switching to soybeans, will have implications. Try to maintain corn rather than go beans-on-beans.
  • Late planting corn — should you increase populations? No, stay the course, unlike with soybeans.
  • Do seed lubricants affect fungicide, insecticide, inoculant? Lubricant rates are too low to influence efficacy.


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