Declining pea yields send pulse group into action


Experts to study problem | A seed grower blames blight while a plant pathologist says root rot is also a factor

Something is happening to pea yields, and Saskatchewan Pulse Growers is determined to get to the bottom of it.


“We are taking some significant efforts to investigate the root causes of this issue and we are developing a plan to address the general (trend) of declining pea yields,” said SPG chair Morgan Nunweiler.


The association has formed a working group comprising pathologists, breeders, provincial pulse specialists and growers to look into the problem. The group will be meeting regularly this winter starting Nov. 1.


“The idea is to basically find out what’s going on and communicate what our findings are,” said Nunweiler. “Together they’re going to bring forward an action plan.”


The association has been fielding calls from disgruntled growers, especially in northwestern Saskatchewan.


Nunweiler said SPG is determined to get on top of the problem before it leads to declining pulse acres across the province.


“We want to prevent the panic of people dropping peas in their production if it’s not warranted.”


The association said it is premature to speculate on the cause of the disappointing yields, although it notes three consecutive years of high rainfall have led to higher-than-normal disease pressure, while extreme heat in July caused pea plants to drop their flowers.


Laurie Wakefield, a seed grower from Maidstone, Sask., is convinced he knows what’s causing the problem.


“Far and away the biggest issue is disease. We’re pretty sure that’s what it is,” he said.


And the most prevalent disease is mycosphaerella blight, one of three ascochyta diseases that affect peas.


He blames the outbreak of the fungus on a combination of growers pushing their rotations, which causes a buildup of the pathogen, and the wetter-than-normal conditions under which it thrives.


“Over the past 10 years, the problem has been building and it was just a matter of time before all the planets lined up,” said Wakefield.


Growers in his area were either happy or disgusted with their pea yields this year. The happy farmers had yields of 40 to 45 bushels per acre, while the disgusted ones yielded 20 to 25 bu..


“A lot of it depended on what you did,” he said.


Farmers who applied fungicide at least once during the year fared better than those who didn’t. 


“We’ve already got our chemical here to apply fungicide applications next year,” Wakefield said.


He worries the pathogen has built up to the point where peas could experience a chickpea-style crash, when an ascochyta blight outbreak helped take a million acre crop down to 130,000 acres in two years.


On the other hand, with peas selling for $9 a bu., some growers are willing to overlook their crop’s poor agronomic performance.


Sabine Banniza, a plant pathologist with the University of Saskatchewan’s Crop Development Centre, said it’s too simplistic to pinpoint the problem on one disease or a collection of diseases.


She has no doubt that mycosphaerella blight has contributed to declining yields, but root rot is also a factor, as is flooding. Legumes don’t like being in saturated soil.


Banniza said mycosphaerella blight has less of a yield impact on peas than related ascochyta blight diseases have on lentils and chickpeas. 


As well, there is no linear relationship in peas between the severity of infection and yield loss.


According to Saskatchewan Agriculture, yield losses of five to 15 percent are common in regions where the disease is established and wet conditions exist during pod development.


Banniza said breeders are trying to improve resistance to the disease, which is not good in existing varieties.


Research shows growers don’t consistently get a response to fungicide applications. Farmers tend to use Headline because the fungicide appears to have plant growth promoting properties, but there is a wide variety of alternatives. 


Banniza said it is a complex problem that requires a multi-disciplinary approach. One thing that is clear is this isn’t a one-off problem.


“This issue of declining pea yields has been coming up over and over again and not just in the northwest but in other parts of the province as well,” she said.


Banniza hopes the working group will have answers by the time growers gather in Saskatoon in January for Pulse Days.

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