Wheat Pete's Word, July 19: Quality losses in wheat, pigweed patrol, corn diseases, and aphid thresholds


Nothing good happens to mature wheat left in the field, and Peter Johnson is pretty thankful that some elevators are taking wheat at 17 per cent moisture to keep combines rolling. It takes a village, sometimes.

For this week’s episode of Wheat Pete’s Word, Johnson also discusses compaction, rescue nitrogen on corn and beans, why a weed “escape” isn’t something to ignore, and making the fungicide call on beans.

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].


  • Pete had to buy his own sweet corn
  • It’s been a tough go with the weather, but we are so fortunate, zucchini notwithstanding
  • On the harvest front, though, if you get the chance, just go go go because the rain has been so spotty and relentless
  • Just go if you can, the straw is tough, but we can’t wait on it because already quality is just starting to go south
  • Falling number starts to tank with poor weather on mature grain
  • Some reports of black point on the kernels
  • Some elevators are accepting up to 17 per cent soft red wheat with shrink only no drying cost. Kudos for doing that! That’s the way to get better quality
  • A caller says here’s just no money in this wheat crop with you. Look at that price inputs. Wait a minute! There is money in wheat if we do it
  • Straw prices are local, but there’s only about 1.5 cents/lb of value of the nutrients phosphorus, potash, nitrogen and sulphur in straw. The rest of the value is in carbon (organic matter)
  • If not winter wheat, what about winter canola? How do you change your rotation?
  • The spotty rain and downpours in Ontario have spoiled hay, and hit the beans hard
  • If you’re seeing tile runs, you know how well your tiles are working
  • If the water isn’t getting to the tiles quickly enough, typically, that’s a deep compaction or a heavy soil issue
  • Norfolk compaction day is set for August 3, get it on your schedule, come on down. It’s the first time we’re ever going to run equipment over the sensors on sand soil.
  • Waterhemp! If you have pigweed in the field that didn’t get controlled, go out and make sure it’s actually pigweed and not waterhemp (or is it resistant?!)
  • If Palmer amaranth gets a hold here, it is eight-way resistant
  • Check out the Agronomists on Monday about novel weed control and also this Soybean School on pigweed patrol
  • There is waterhemp in Pete’s area that just thick as hair on a dog’s back
  • So if you see just the odd pig weed out there, my goodness, get out there gets take a sample, send it away, find out if it’s waterhemp
  • Kim Brown Livingston from Manitoba saying that in Manitoba waterhemp is a noxious weed and so if it’s found they have to destroy it
  • On to yellow beans — can foliar N help water-logged beans? Try it and leave a test strip
  • Will a fungicide pay on beans this year? It’s a timing thing. We always get higher return to fungicides when we have disease. Lush beans will benefit from a fungicide almost for sure, but there’s no guarantees
  • Soybean aphids are out there but many fields are just approaching threshold. Use the Aphid Advisor app
  • Mummified aphids are out there too! Deb Campbell (@DCHighlander) tweeting out an amazing picture of a wheat head that was just covered in mummified aphids. The fungal pathogens that attacked the aphids, that’s what’s really going to keep them in control!
  • Alert! Tar spot in corn. It’s shown up in the traditional hotspots. It’s absolutely there. But it’s it’s actually not progressing as rapidly as you would expect it to. Tar spot needs seven hours of leaf wetness
  • A few things to think about on a silage corn front: tar spot takes over the leaf surface area
  • If you go from London, south and west, that areas had a lot more tar spot. When we go from London north and east we’ve had tar spot but it’s generally come in late and so we don’t think that perhaps the inoculum levels are quite as significant. Remember green silk timing is key for most fungicide passes
  • If you have a corn hybrid that is susceptible to Northern corn leaf blight, this is a heavy infestation year
  • Smut is out there too
  • Yellow corn? Do you add N?
  • Back in 2016, we had six inches of rain in June before the corn really got going, it was maybe only knee high. Greg Stewart went out and put 50 pounds of nitrogen on for a 30 bushel yield increase. If you’re seeing yellow corn, and you can get through the crop chances of seeing some yield benefit to a late nitrogen application in this situation may well just go up pretty significantly
  • Pre-harvest pass of glyphosate on wheat might be worth it for combine management (too much green)
  • Any time you can trade straw for manure is a good deal
  • Revitalizing an old cow pasture — do I add oats or do I add fescue. Fescue is incredibly slow to establish and you’d have to keep the cows off while it does. You could add oats that will give you some pasture more quickly this fall, but only a short term fix. Maybe cereal rye is better
  • If oats are the cover crop of choice, make sure to add N. We need 50 pounds of nitrogen so that we don’t have a negative impact next year on the corn crop from that oat crop
  • Go back over the field history, and calculate what yields have been on that field and do the phosphorus and potash calculations if straw was removed. Many growers we are getting such big yields and are not keeping up on phosphorus and potash


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