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In early July last year, calls were coming in from multiple farmers in the Tisdale area. They were concerned that some of their crops, in particular the pods of canola plants, were being eaten.

The main crops grown in the area consist of canola, wheat, barley and oats along with some pea and flax fields. Bill called to invite me to stop by his farm and scout his canola field.

“I’m not sure what insect is in my field,” explained Bill. “But something is eating the pods of the canola plants, and it’s not just my field. My neighbours are also noticing the same problem.”

I arrived at Bill’s farm and we went straight to the problem field. At first glance, the canola crop looked normal and healthy, but on closer inspection bite marks were clearly visible — mostly on the canola pods. The damage being done to the pods could really end up hurting Bill’s bottom line.

Bill first noticed the insect damage when the canola crop was around the 20 to 30 per cent blooming stage. The entire area had received quite a bit of moisture, which had been followed by some warm, humid days. These conditions not only lead to increased insect pressure, but disease pressure as well.

As we walked through it, we noticed many insects flying around and throughout the field. Since we had already determined that disease was not the cause of the problem, I decided the next best step would be to conduct a sweep net test. Not only would this help me determine the type of insects present, but also how high or low the insect pressure was within the field.

The sweep net test revealed two things to me — first, it was the light-coloured “V” or triangular shape on the insect’s upper back that gave away its identity and, second, that this field was at its threshold.

“Bill, you need to manage this problem right now before it’s too late to help your crop,” I said.

What insect is taking a big bite out of Bill’s canola yield? Send your diagnosis to Grainews, Box 9800, Winnipeg, MB, R3C 3K7; email [email protected] or fax 204-944-5416 c/o Crop Advisor’s Casebook. Best suggestions will be pooled and one winner will be drawn for a chance to win a Grainews cap and a one-year subscription to the magazine. The best answer, along with the reasoning which solved the mystery, will appear in the next Crop Advisor’s Solution.

The winner of the last issue’s Crop Advisor Casebook was Alberta farmer Isaac Wurz. We’ll be sending him a cap and renewing his subscription for a year. †

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