Pulse School: Persistent damp conditions up the ante on disease pressure

Pulse crops are efficient water users. Field pea, lentil and chickpea are all great at adapting to drought-like conditions, which makes them a great option in just about every soil zone of the Prairies. However, being well adapted for drought means that most pulse crops do not like wet conditions, which isn’t really something farmers can control.

Jenn Walker, research manager for Alberta Pulse Growers Association, says that there are some management strategies for dealing with wet soil conditions, if you know that’s what you’re heading in to.

In this episode of Pulse School, Walker suggests using a seed treatment to help mitigate some of the effects of pulse diseases and to protect seedlings. “One of the troubles that we’re seeing with this season in particular is seed treatments only have a two- to maybe three-week window of protection, and of course we’re way past that, and we’re still seeing these wet, wet soils,” says Walker.

When you’re out scouting fields, look for yellowing which is an indication that plants are stressed. Take a shovel, dig up some plants in those yellow spots, and look at the overall conditions of the roots, advises Walker.

Root rot diseases like fusarium, rhizoctonia, or pythium species are covered by seed treatments, but aphanomyces is not. Some treatments may help with aphanomyces but there’s no “silver bullet” says Walker, nothing will really help this late in the season. Compaction from equipment might also play into additionally stressing plants.

Healthy root systems, mean healthy plants, and these diseases could ultimately lead to a yield hit, especially if the plant can’t grow out of the disease. Persistent wet soil conditions will also affect biological nitrogen fixation of the plant, because nodules need air from soil atmosphere to transform N into a useable form for the plant. Furthermore, if a root rot disease has severely affected a plant, it may not even have nodules.

“The biggest thing we need to do, is actually take note of those areas in the field, go back and soil sample, because if there is aphanomyces there we need to take that into consideration for when we’re planning our crop rotations and choose pulse crops that are resistant,” says Walker.

Aphanomyces stays in soil for a long time and it’s recommended that susceptible crops like peas and lentils should only be included in the rotation every six to eight years. Faba beans provide a good alternative in a rotation because they are not susceptible to aphanomyces. Walker suggests managing problem areas of a field independent of the rest of the field.

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