U of I Researchers Target Sugar Beet Disease

Jan 22, 2024

University of Idaho researchers have promising leads on management practices and new pesticide options to help the state’s sugar beet farmers get a handle on a fungal disease that’s posing an increasing threat in their fields.

Cercospora beticola thrives in moist, warm conditions and creates necrotic spots on sugar beet leaves. Plants expend their energy regrowing dead or damaged leaves at the expense of sugar production, resulting in yield losses of up to 40% in susceptible cultivars.

James Woodhall, an associate professor of plant pathology based at the U of I Parma Research and Extension Center, and his graduate student, Hayden Woods, obtained an $18,000 grant through the U.S. Department of Agriculture’s IR-4 Project to evaluate seven different fungicide programs for controlling the disease.

IR-4 develops data for the registration of safe and effective pest management solutions for specialty crops with the U.S. Environmental Protection Agency.

Amalgamated Sugar Co. is conducting separate trials assessing the same fungicide programs.

“This is a sugar beet disease that is gaining importance in Idaho. It just seems to be getting more and more severe,” Woodhall said. “It was first found in Idaho in the 1960s, but it’s slowly getting worse.”

Woodhall believes a combination of factors have contributed to mounting grower headaches from Cercospora beticola.

Changes in irrigation likely play a role, as most farmers have switched from in-furrow irrigation to overhead sprinklers, which moisten leaves and create favorable conditions for spores.

He also suspects the disease is entering the state on growers’ sugar beet seed and is likely over-wintering in infected sugar beet tissue in fields.

Large Cercospora spores don’t travel far but can take hold in adjacent fields and spread slowly from one field to the next.

Perhaps the greatest challenge growers face in managing Cercospora is that it quickly develops resistance to pesticides. Woodhall and Woods have sought to identify new modes of action to include in pesticide programs to avoid the onset of resistance to commonly used products.

“The long-term approach is we need to have resistant varieties,” Woodhall said. “Our near-term approach is we need cultural management and we need additional chemical management options.”

Woodhall and Woods enjoyed good results with a treatment regime that included an application of a fungicide that’s already labeled for sugar beets but not widely used, containing the active ingredient thiophanate-methyl.

The addition of that product contributed to a 67% reduction in disease pressure, compared with a 35% reduction resulting from a comparable program that didn’t include thiophanate-methyl.

They also found two fungicides that aren’t currently labeled for sugar beets that provided strong control against Cercospora beticola.

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Video: Can Gene Editing Give Seeds a Stronger Start?

Reagan Reed has a way of describing his research that might make a plant breeder pause.

“I’m the sort of person who likes to break things to understand them,” he says.

What he breaks are genes involved in seed germination. Reed, a Ph.D. candidate at the University of California, Davis, is investigating whether changing those genes can help seeds establish healthy plants under a wider range of conditions.

Reed recently attended the National Association for Plant Breeding meeting in College Station, Texas, as an NAPB Borlaug Scholar. His work speaks to a question that matters well beyond a research lab: what does it take for a seed to get a crop off to a strong start?

A seed that germinates quickly, alongside the others planted with it, spends less time vulnerable to stresses before seedlings become established.

“If you’re able to bridge that gap between germination to stand establishment, then that’s going to give you the highest probability of having a solid yield that year,” Reed says. “There’s a bunch that can go wrong after that, but it maximises your yield from the start, at least.”

Reed works in Dr. Imtiyaz Khanday’s lab at UC Davis, where his research focuses on seed quality in tomatoes and potatoes. He brings an unusual academic background to the work: at Skidmore College, he studied both biology and Latin.

Reed believes that combination prepared him for research. Translating an ancient text means studying each word, weighing its possible meanings and using context to reach the best interpretation. There is rarely a way to know with complete certainty what an author intended. Science, he says, requires a similar willingness to work through uncertainty.

“Attention to detail and comfortability working with uncertainty,” is how he sums up what Latin taught him.

In the lab, uncertainty can produce a surprise. Reed describes changing one gene and seeing little effect. Changing a second gene also appears to do little. Put both changes in the same genetic background, though, and the result can be substantial.

“I break this gene, nothing really happens. I break this other gene, nothing really happens. I combine them into the same genetic background, and now there’s a massive effect,” he says.

Those interactions matter as researchers gain the ability to edit multiple genes at once. They also complicate any simple account of how a trait works: improving a seed may depend on understanding what several genes do together.

For Reed, the question is whether that knowledge could help seeds germinate reliably when conditions are difficult. Some of the genes he studies prevent germination under certain conditions. That response may serve a plant well in one setting while limiting its usefulness in agriculture. He wants to learn what happens when those genes are changed, and whether the result improves establishment.

Yet a discovery that works in a lab still has a long way to travel before it reaches a field. Reed argues that agricultural biotechnology faces an economic challenge as well as a scientific one. New tools can create value for farmers, he says, but developing them requires a way to support the work in an industry where margins can be thin.

His fellowship with Flagship Pioneering gave him a view across AI, agriculture-related work and human health research. It also reinforced the importance of bringing people with different expertise into the same conversation—a benefit of gatherings such as the NAPB meeting.

“You need to have a team of people with different backgrounds who are willing to work together and approach the same problem in different perspectives and different ways,” he says.

That thinking connects the different parts of Reed’s path. Latin taught him to examine details without expecting a perfect answer. Gene editing lets him test what individual genes do—and what happens when their effects combine. Working with people beyond his own field helps him ask what those findings could become.

He came to agriculture because of its reach: the possibility that work by a small group of researchers could eventually make a difference on a much larger scale. His immediate focus is smaller and more precise. He wants to understand what helps a seed get through its first days and become a healthy plant.