Scientists work to reduce bean diseases

Some of their work was displayed during the Manitoba Pulse Growers Association’s recent annual tour

Can the same technology that warms up leftover pizza control seed-borne diseases in beans?

A University of Guelph master’s student is hoping to find out.

Allison Friesen is testing microwaves on seed-borne diseases such as halo blight and common bacterial blight, two diseases that can cut into yields and quality.

“She spent the winter with various treatments to see how much exposure you could apply and not affect the viability of the seed and that’s what we have here (in our plots),” Bob Connor, a pulse crop pathologist at Agriculture and Agri-Food Canada’s Morden Research Station, told producers attending the Manitoba Pulse Growers Association’s (MPGA) annual tour Aug. 1.

The research is showing too much time under the rays can be damaging. “It seems if you leave them too long, even if they germinate they are very weak and they don’t produce good, vigorous seedlings.”

Although microwaves have been tested on other crops, this is the first time for beans, Connor said.

Halo blight, which causes a yellow discolouration on bean leaves with a pin-sized brown spot in the middle, usually occurs under cool, wet conditions. It sometimes shows up early in the growing season and disappears if the weather turns hot and dry, Connor said.

“We had a big outbreak of it about four years ago around Portage,” he said. “It was quite bad in certain bean cultivars, most probably because the seed was infected.”

The disease can be especially bad in kidney beans, but that year navy and pinto beans were also infected, Connor said.

Although the disease can be on the outside of the seed, it can also be just below the seed cover, making it more difficult to kill.

The Morden Research Station is doing research on other bean diseases, thanks in part, to MPGA funding made possible by producer checkoffs.

One of those diseases is anthracnose, a fungus disease that can cut bean yields by 30 per cent. Connor said it’s not as serious a problem now compared to a few years ago because of fungicides and improved seed. The disease, which causes lesions on bean seeds, also reduces seed quality and the crop’s value.

Grow out

Researchers are looking at a combination of resistant varieties and agronomic practices to control anthracnose, he said. Seed size, colour and planting date are being examined. Earlier seeding might allow the crop to outgrow the disease.

Jeff Boersma is working with Morden Research Station bean breeder Anfu Hou to develop varieties resistant to common bacterial blight. A couple of the new lines from crossing OAC Rex, a late-maturing white bean from Ontario, with Morden 3, are showing good resistance to bacterial blight, Boersma said. They are also resistant to anthracnose and common mosaic virus. These lines will be crossed with others in an effort to get good disease resistance along with a superior-performing bean. Root rots are also being investigated.

“We have a major concern about this disease because it’s the sort of thing that tends to build up after a number of years the more you have beans grown in short rotations,” Connor said.

It can take up to 10 years for sclerotia spores to die once a field becomes badly contaminated with inoculum. “So we think developing varieties with better resistance and also making sure farmers practise better crop rotation will go a long way to preventing this disease from becoming a major problem.”

The tour included a stop at plots assessing new, later-maturing soybean varieties for Manitoba. There’s a similar site at Rosebank, said Dennis Lange, a farm production specialist with Manitoba Agriculture, Food and Rural Initiatives.

An early spring saw some Manitoba farmers planting soybeans as early as May 1, he said.

“For the most part everything made it OK, even with the frost we had at the end of May,” Lange said.

As of Aug. 1 much of Manitoba’s soybean crop was in good shape, but would have been even better off with additional rain a few weeks earlier. Rain even last week would have boosted seed size, he said. Much of south-central Manitoba had received 105 to 110 per cent of normal heat units as of Aug. 1, while the southeast had received 110 to 113 per cent of normal, Lange said.

Heat units were a bit below normal in the southwest and around Roblin in the northwest, he said.

Two non-Roundup Ready soybean varieties from Ukraine are also being grown in Morden to see how they do. Both have atypical dominance, meaning the majority of pods are supposed to be higher on the plant, Lange said. Higher pods are easier to get into the combine.

But maturity is a concern. “There are lots of heat units this year and that’s a good thing, but if we get into a cooler, wetter year then these longer-season ones may not be suited for us,” he said.

About the author


Allan Dawson

Allan Dawson is a reporter with the Manitoba Co-operator based near Miami, Man. Covering agriculture since 1980, Dawson has spent most of his career with the Co-operator except for several years with Farmers’ Independent Weekly and before that a Morden-Winkler area radio station.



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