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Crop Advisor’s Casebook: Canola crop puzzle

A Crop Advisor's Solution from the March 3, 2015 issue of Grainews

Dustin Miller

Dustin Miller
photo: Supplied

Joe, who grows canola, wheat and barley at his farm near Spring Coulee, Alta., called me in July to alert me to a problem with one of his crops. His canola in some areas of the field wasn’t doing well, and he had been told by a retailer that poor seed might be to blame. Joe asked me to come out to have a look for myself.

When I arrived at the farm, I could see that canola plants in a low part of one field looked stunted and were dropping flowers. Wheat plants in adjoining fields were doing just fine, but in another canola field next to the wheat, some of the canola plants were exhibiting similar symptoms.

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Because the pattern of the canola damage didn’t extend to the whole field, it didn’t look like the problem originated with the seed. I wondered if a nutrient deficiency could be to blame, but there didn’t appear to be any issues with Joe’s fertility program either.

When I asked Joe about his crop protection program, he said he had applied Roundup to his canola and had sprayed his nearby wheat fields with a broadleaf herbicide in June.

Joe wondered if weather might be a factor, but frost damage wasn’t likely this far into the growing season. There had been quite a bit of precipitation recently, however.

By this time, I had a pretty good idea what was going on with the canola crop. When Joe told me what the weather had been like when chemicals were applied to the fields, my suspicions were confirmed.

Crop Advisor’s Solution: Pesticide drift causes dropping canola flowers

The indications were that this was in part a Mother Nature problem. When Joe told me that a wheat field just to the north of the first canola field had been sprayed with a broadleaf pesticide in June and described the weather conditions that day, it confirmed my suspicions about what was causing the canola damage.

On the day of that spray application, it had been on the cool side and there was no hint of wind. Joe told me the worker who applied the pesticide reported that it had stayed suspended in the dead calm air rather than settling to the ground, indicating a temperature inversion was occurring. From the damage pattern, it was pretty obvious that the suspended chemical had eventually drifted southwards, following the draw that ran though the adjoining canola and wheat fields.

It was this pesticide drift that had damaged plants in the lowest areas of the canola fields but had left the wheat crop unharmed. Unfortunately for Joe, there was nothing to be done to salvage the damaged crop, and he ended up with a zero yield for the affected areas of his canola fields.

To prevent problems like this on their farms, growers should always be keenly attuned to the weather and avoid spraying crops when the temperature conditions are ripe for an inversion. Similarly, farmers should keep a close eye on the wind to make sure the chemicals they are applying are going precisely where they should be.

Dustin Miller is a sales agronomist with Richardson Pioneer Ltd. at Magrath, Alta.

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