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Healthy crops need to breathe

Mike, a Nampa-area farmer who farms 7,000 acres of canola, wheat, barley and yellow peas with his brother Joe, dropped by my office at the end of July. The brothers were concerned about their field of peas that were stunted, turning yellow and dying. “I’m positive it’s from chemical damage,” explained Mike. Joe asked if I would have a look and give them a second opinion.

After walking through the field, it was evident that something was very wrong. Not only were the pea plants dying but even the weeds were having a difficult time growing. Disease was also visible right at the soil surface on all of the plants.

Joe didn’t believe that the damage was caused by chemicals. “Previously, this was a fescue seed field with a healthy crop,” he said. Joe explained that only one litre of glyphosate had been used on this particular field during the past five years. He believed that poor nodulation was the problem.

Chemicals can cause significant plant damage; however, this was not the case in this field. In the previous week this farming area had received abnormally wet weather and upon closer inspection I noticed various stages of maturity and injury. Nearly 70 per cent of the plants were dead or well beyond rescue. There was one exception in the field, a path of approximately 10 feet along the road ditch and fence line where healthy plants were growing.

After asking a few more questions, I learned that the clay soil field had been lightly tilled in the spring and phosphate and a granular inoculant had been applied at seeding. After digging up and examining the roots of both the unhealthy and healthy plants, I knew what the problem was — severely compacted soil conditions causing root rot!

This clay soil field had been lightly worked in the spring and recent heavy rains had caused severe soil compaction, with the exception of the 10-foot area of healthy plants, where the soil was noticeably looser. The soil within the field was very hard to dig into and I found that the roots were healthy but all of the plants had rotted off at the surface resulting in mycosphaerella blight and foot rot, due to excessive water. These fungal pathogens spread easily under wet conditions.

The solution for this field was to break up the compaction layer so that the soil could drain better. In order to grow a healthy crop, peas require fields that drain naturally or are sandier so there is less water pooling on the surface. As well, when taking fields out of grass seed, the soil should not be worked finely. Mike and Joe’s field of peas produced no yield as the plants were so badly injured by root rot that they were not worth harvesting.

In order to avoid this problem in the future, Mike and Joe plan to be more careful when choosing a field that will be used for pea production and will be more aware of soil compaction during heavy rainfalls. They will also consider the application of fungicides when conditions are cold and wet, which will help prevent major losses like the one they experienced. Finally, having a good agronomic plan in place, including fungicides, will help Mike and Joe — and all farmers — meet and exceed their production goals. †

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