Wheat School: Identifying the flag leaf


With winter wheat progressing rapidly through its growth stages in Ontario, RealAgriculture agronomist Peter Johnson is advising growers to keep a close eye on the crop.

With crop development running 10 days ahead of schedule, Johnson says wheat fields need to be scouted to make critical management decisions to optimize yield. On this episode of the Wheat School, he heads to the field to demonstrate how growers can identify the penultimate leaf and flag leaf, and effectively time weed control and nitrogen and fungicide applications.

Johnson notes that growers need to be careful to not burn the penultimate leaf if they are planning a last nitrogen application before the flag leaf emerges. Flag leaf emergence is a signal to cease applying weed control. “It’s just too high risk,” he adds.

It’s also important for growers to scout and look down into the canopy to identify any disease that may be present.

“If you have powdery mildew and septoria, we need to keep the penultimate leaf and the flag leaf clean,” says Johnson. “Remember fungicides don’t have good mobility in the plant so when the penultimate leaf is fully out and we see the flag leaf starting to spike — that’s the perfect timing for that first fungicide application if it has not been applied with the weed control.”

With everything under control in the canopy, growers are then well-positioned to protect the flag leaf with a T3 fungicide. (See video below.)

Click here for more Wheat School episodes.

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Wheat School (view all)Season 12 (2021) Episode 23

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