Orville called me at the end of June. He is a hog and poultry farmer and has about 1,500 acres southeast of Winnipeg.
Orville’s winter wheat was chlorotic. The flag leaf was just emerging from the boot. Its tip was yellowing and getting worse by the day. Unfortunately, it was an unvarying symptom throughout his crop, appearing as a yellow tinge on the field.
“It’s developing quickly and hitting hard. I think I’ve got to get some fungicide on this right away,” Orville said in a bit of a panic.
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I checked my records for Orville. His original plan was to apply fungicide the following week, when the flag leaf would be fully emerged. I convinced him to hold off until I came to see his wheat.
The next day at Orville’s kitchen table, we considered his rotation. Perhaps he was transferring a disease from last year’s crop into this year’s winter wheat, but his records showed a canola-wheat rotation, so that wasn’t the problem.
Maybe it was the nitrogen content of the soil. Orville had a team apply manure to the field the previous fall. Manure is very often the culprit behind a yellowing crop because you can’t be certain exactly how much nitrogen will be released into the soil. But the soil sample showed the manure application had offered up 50 lb. of nitrogen. This confirmed our calculations earlier in the season when Orville had applied 40 lb. in the spring, in addition to the starter blend of fertilizer with the seed.
We headed out for a look at his winter wheat. Looking out over this yellowing crop, we were second-guessing ourselves. Orville’s wheat should’ve been nicely lush and green. Except for a night of strong winds, the spring had offered prime growing conditions. The crop had seen adequate moisture and timely and strong sunlight. It had been growing well early on, so maybe the winter wheat was actually running out of nitrogen.
We got out of the truck for a closer inspection. Orville confirmed that the yellowing of the flag leaf, from inch right up to 1 inches, had worsened since his inspection only two days ago. But the rest of the plant below the flag leaf was still green and lush.
Why the yellowing of the flag leaf? Send your hypothesis to COUNTRY GUIDE,
1666 Dublin Ave., Winnipeg, MB R3H 0H1; e-mail [email protected];or fax 204-947-9136 c/o Krista Simonson.
Correct answers will be pooled and one winner will be drawn for a chance to win a COUNTRY GUIDE cap and a one-year subscription to the magazine. The correct answer, along with the reasoning which solved the mystery, will appear in the next Crop Advisor’s Solution File.
