Plant pathologist tackles mildew disease problems


Capital Press

CORVALLIS, Ore. -- David Gent felt like he won the lottery five years ago, when he landed a job as a plant pathologist in hops in the Willamette Valley. But it may be hop growers who hit the jackpot.

Gent, a research plant pathologist for the USDA Agricultural Research Service, recently was awarded the agency's prestigious Pacific West Area Early Career Scientist Award.

The Pacific West Area includes 21 research locations in eight Western states.

Gent grew up on a farm in Junction City, Ore. After obtaining his doctorate in plant pathology at Colorado State University he hoped to land a job in Oregon.

Getting a job in his field just miles from where he and his wife, Breanna, grew up was a bonus.

"Getting a good job, where you want to live straight out of school is kind of unheard of," he said.

Gent, who obtained his bachelor's degree in crop and soil science from Oregon State University, has already had an impact on hop production in the Northwest, said Gary Banowetz, research leader for the ARS Corvallis center.

"In five short years, he has really had a lot of impact in learning how these mildew diseases develop and in helping growers plan a science-based and economical approach to controlling them with fungicides," Banowetz said. "He has developed models based on weather and other factors to help growers decide when to spray."

Gent brought a fresh outlook to Northwest hop production that he believes helped him develop new solutions to old problems.

"Not being familiar with the crop was an advantage in some ways," Gent said, "because I was able to look at some problems that have been around a long time and ask questions.

"We've kind of re-evaluated some questions that maybe some of the growers thought were solved years ago," he said. "We were able to look at some of their cultural practices and the way they approach disease management in a new way."

Among advances Gent has pushed is a change in the timing of spring pruning. Pruning later in some varieties, particularly Willamettes, can reduce downy mildew pressure and increase yields.

"Simply by delaying their pruning 10 to 14 days, we're seeing in some cases up to 80 percent better disease control without any additional fungicide applications, and typically it involves one less application per season," Gent said.

"We've found that what they do in March can shape the entire epidemic for that season," he said.

Gent has also contributed to the understanding of powdery mildew and how management of that disease has led to flare-ups of spider mites.

"We've been able to sort out that some of the fungicide that the growers are using to control powdery mildew -- specifically sulfur -- can have negative effects on spider mites and biocontrol of spider mites," he said.

Part of optimizing powdery mildew control while minimizing mite flare-ups is knowing when hops are most susceptible to the disease, Gent said.

"What we're seeing is there appears to be a really critical timing for cone infection.

If a grower can minimize cone infections during a relatively short window, they can reduce the amount of disease they see at harvest by up to 50 percent in some cases," he said.

Gent also has helped develop disease forecast models based on weather and other factors to help growers time sprays for when cones are most susceptible.

"He was an exceptional undergraduate student, and he has proven to be a great scientist," Banowetz said. "And he works with the industry folks well, too."

Gent said being from the area helps him relate with growers.

"I think I have a good understanding of the issues they are facing and the limitations they have in terms of economics. And I think they appreciate that sort of perspective," Gent said.

"Frankly, I would've taken any job in Oregon probably independent of the pay," he said. "It was kind of like winning the lottery."

Staff writer Mitch Lies is based in Salem. E-mail:

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