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Bare Patches And Missing Rows Point To A Pest

Tom, a producer who farms 5,500 acres of canola, barley and wheat south of Carseland, Alta., called me at the end of May last year about his poor wheat stand. “My crop’s coming in well, but I’ve got some bare patches in my field, and a couple of rows are gone,” he said.

I headed out to Tom’s farm that afternoon. The majority of the 300-acre wheat field looked healthy with a good stand, but the east side was thin. Here I found bare patches with few or no plants as well as some areas where whole rows were missing.

Initially, Tom thought the problem had been caused by equipment failure at seeding, resulting from a plugged run in his drill. But I found no consistent evidence in the field to support this. We also discussed fertilizer rates, seed treatment and drill speed, but nothing seemed out of the ordinary. In fact, all of Tom’s machinery was in good working order, and his settings for seeding rate and depth worked out as he had planned.

It was time to consider other possible sources of the problem, such as environmental conditions, seed lot quality, herbicide carryover, disease, insects or rodents.

To begin finding an answer for Tom, I first considered the seed itself. Tom had purchased certified seed from our retail location, and the seed analysis was excellent for germination and vigour. The majority of Tom’s field was healthy and growing well, so poor seed lot quality was not the problem.

I dug into the seed row in one of the thinner areas and I found seeds present with roots forming, thus confirming poor germination was not a factor.

Visually, there weren’t any signs of herbicide carryover, and Tom’s field records confirmed he hadn’t used any herbicide chemistry with residual activity on this field that would be a cause for concern.

With our list of possible causes of the problem narrowing, I considered the environmental conditions from the time of seeding up to the appearance of the bare patches and my visit to Tom’s farm. Besides cooler than normal temperatures that spring, the weather had been fairly average at the time of seeding and during the time leading up to crop emergence. After crop emergence, the temperature did not dip below zero, eliminating frost as a cause of the damage. Also, most of the wheat stand appeared heal thy, moving environmental conditions further down the list of probable causes for the missing plants.

After scouting the field, I determined disease was also not a factor, and there were no signs of a gopher population in the area. Now we were at the bottom of the suspect list — insects!

Because wireworms had been reported in the surrounding area the previous spring, Tom and I had set traps earlier in the season, but we found nothing. Tom felt sure we weren’t dealing with wireworms.

I went back to the seed rows where the plants were completely missing, and after digging in the dirt for a bit, I found something interesting — some plants, which had germinated and formed roots, were broken off at the soil surface. I thought again about the cool spring temperatures — could it be possible? I stood up and faced Tom, pretty sure I now knew what was going on. “I think I know what’s happening to your wheat,” I told him.

Who’s dining on Tom’s wheat and what can be done about it? Send your diagnosis toGrainews, 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 aGrainewscap 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 File.

JasonHoffmanisacropinputmanagerat RichardsonPioneerLtd.inCarseland,Alta.

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