Wheat Pete's Word, July 27: Drought-induced deficiencies, an aphid alert, and big biomass


We’re rounding out the last full week of July, and some areas of Ontario are just getting by with a few dribs and drabs of rain here and there. Still others have enjoyed plentiful moisture and will be on patrol to find signs of western bean cutworm, white mould, and aphids.

For this week’s edition of Wheat Pete’s Word, host Peter Johnson talks water use, induced deficiencies, cover crop fertility planning and so much more!

Have a question you’d like Johnson to address or some yield results to send in? 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].


    • In Ontario? There are lots of learning opportunities starting to come up with Soil & Crop tours Aug 4th and 5th, Elgin and Perth. Contact the director or visit the website
    • Did you catch Monday’s episode of The Agronomists? Go and listen/watch!  Greg Stopps and Ken Currah talking tar spot and gibberella in the corn crop
    • Last year, we had the perfect storm for tar spot. This year, so far, there are only low levels out there
    • Gibberella can happen in really low rain conditions, too, because humidity can really catch us off guard
    • Some areas of Ontario have basically received zero rainfall. On the light ground, the crop is really in awful shape. Some growers are starting to get little dribs and drabs
    • There is some unbelievable drought out there in western Kansas, Texas, if you look at the U.S. Drought Monitor, wow, there was some tweets coming out of western Kansas.
    • Shaun Haney and Pete had a good chat about extreme weather on Monday’s RealAg Radio show on SiriusXM, including high winds and hail in large areas
    • Denver in Alberta had a massive wheat winter crop coming and he got hailed out so instead of having a great crop and seeing how good winter wheat could be in Alberta, not he had to take it for silage. He did say about 50% of the grain had been knocked out of the heads, but the tonnage he was still getting off that field was absolutely amazing
    • Wheat yields are all about biomass! In the YEN program, big biomass makes big wheat yields
    • Grain is simply a high proportion of the total biomass, and we call that the harvest index. So the amount of grain versus the amount of stover, that’s the harvest index. With wheat, it’s about 50 to 55 per cent,
    • It is astounding how well the corn and soybeans and edible bean crops are hanging in there, they’re not great. But wow, on good soil, the crops seem to be performing reasonably well. Given the dryness, how can that be? One of the things that is really helping are the cool nights
    • Small rains are making a difference, too. Even just five millimetres is almost enough water for a day. Don’t forget, the corn plant also funnels rain down to the base of that that corn plant. So it’s going to get as much use as it can
    • Compaction exacerbates drought stress because the soil pores get squished and we don’t get that lateral water movement to the corn plant
    • But even a one-day reprieve of 5 mm is a boost!
    • Darryl tweeted out a picture of a plot that he did. The high yield on wheat 170 8.6 bushels per acre. Wow! (See below)
    • Don’t feel bad about 100 bu/ac wheat, given the conditions
    • Across the board, the wheat yields just keep coming in big and bigger and biggest is just it is phenomenal
    • Remember when measuring yield: be really careful if you’re using the buggy. When verified on the scale, the buggy  was out by 9% — so 165 bushels per acre was really 151 bushels per acre. Calibrate!
    • Lots of manganese deficiency showing up on sand soils, but the new growth was okay because the field got an inch of rain.
    • Manganese doesn’t move in the plants
    • Potassium deficiency showing up in corn, soybeans, and edible beans. If your soil tests are solid, it’s just drought-induced, but it is worth looking at your soil tests and at your fertility program
    • In Western Canada, where the soils are inherently incredibly high in potash, even then in a really dry year, there’s just not enough moisture around the soil particles to allow the plant to access the potash. And so in those really dry years, a bit of potash in the starter fertilizer actually helps
    • Why do we always talk oats as a cover crop, what’s the matter with barley? Oats do have a bit better root system, and barley is more daylength sensitive and it won’t give you the growth that oats do
    • Oats definitely have some problems in terms of rust. Ellen Sperry found stripe rust in the spring wheat crop and she also found leaf rust and crown rust in oats
    • If you are looking at oats as a forage, find a moderately-resistant variety at gocereals.ca
    • Barley makes less forage, but you wouldn’t have to spray it with that fungicide to keep it clean
    • What about fertilizer with our cover crop oats? Right now, in dry conditions, you have to consider the high salt index of potash fertilizer but MAP is OK
    • A number of growers saying, why drill in the cover crop, why not broadcast? There’s nothing wrong with that it; oats seem to do really well in that scenario. The challenge, of course, is that you don’t get quite as good establishment so you generally have to up the seeding rate
    • Looking (again) at broadcasting winter wheat into standing soybeans. Early September broadcast can work in some years, but don’t assume it will in all areas or every year
    • What’s with all the leaf hopper in soybeans? There’s no threshold for leaf hoppers in soybeans because the hairs on the soybean leaves stop the leaf hoppers from feeding. It’s same with leaf hopper resistant alfalfa, but remember the alfalfa doesn’t put out those hairs in the first year
    • Eastern Ontario Alert! Soybean aphids on soybeans and white mould conditions!

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