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In May of last year, I received a call from an Alberta farmer with 5,000 acres of barley, wheat, canola and alfalfa. Concerned about the yellow patches appearing in his barley field, Byron asked me to visit his operation to take a look.

He first noticed the problem at the edge of his field bordering the highway. “I’m unsure what’s causing it. Given the spring we’ve had, it could be caused by frost or excess water, chemical damage or leaf disease,” said Byron.

Upon arriving at the field, I noticed yellow patches at the very edge of the crop, and the plants were stunted in growth. When encountering symptoms such as these, over-application of fertilizer can sometimes be a factor to consider. However, I quickly eliminated this possibility because the patches were circular in shape rather than the linear or square damage caused by an error in fertilizer application. Drought could also present symptoms in this way. However, given the wet spring of 2012, I knew this could not be the cause of the damage in Byron’s field.

Although the area had seen quite a bit of moisture, excess water damage was also not the issue because the stress on the crop was localized to the outer edge of the field.

Barley is typically quite tolerant to temperatures up to -6 C. However, temperatures had not approached this value, also ruling out the theory of frost damage, and the leaves were yellow rather than the brown colour of frost-damaged plants.

As we examined the damaged plants more closely, we discovered some tiny insects hopping around on the plants’ leaves.

“Here’s a red flag,” I said to Byron, pointing at one of the small, yellowish, wedge-shaped insects I’d found in the damaged area.

What insect is causing the damage to Byron’s barley field? 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. †

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