Most serious potato disease shouldn't be kept secret, researchers say


Capital Press

The rise of the Internet and cell phone technology has made tracking pest and disease outbreaks easier than ever.

But the new tools don't help much if farmers don't report outbreaks in the first place, experts say.

In the potato industry, reporting late blight can be a sensitive matter. Some farmers are reluctant to report outbreaks for fear they won't be able to market the crop or that they'll be viewed as bad farmers.

"I think there's a stigma attached to it," said Phil Nolte, a University of Idaho Extension seed potato specialist.

Unfortunately, keeping an outbreak under wraps can put unsuspecting neighbors at risk, Nolte said. Nearby farmers might be more inclined to take precautions such as applying protective fungicides if they know the disease is present.

If researchers aren't aware of suspected late-blight-infected fields, they can't confirm it in the lab or make an announcement alerting other growers.

There may be some justification for the fear that part or all of an infected crop could be rejected, Nolte acknowledged. But much depends on the market and spud supplies, he said. A certain amount of defects are permitted before potatoes are determined to be off-grade, and contract buyers are less likely to reject an entire crop if supplies are tight.

Nolte said the "culture of fear" that keeps some farmers from reporting late blight is most apparent in Idaho.

The prevailing attitude is quite different in some other growing regions.

Nolte said he attended a meeting this winter in Canada where he was told that growers in Ontario not only share the specific location of late blight-infected fields, but they announce the GPS coordinates.

By contrast, late blight announcements in Idaho are intentionally vague as to location and may not even specify the county where the outbreak occurred.

Late blight is the most serious disease of potatoes worldwide. Once it gets into a field it can quickly spread and cause major damage, Nolte said.

The disease thrives in cool, wet weather. Thunderstorms, coupled with sprinkler irrigation, can provide the perfect environment for spreading the disease.

"Once it gets into a field where you are using sprinkler irrigation ... it can really spread," Nolte said.

There's also a danger in areas where the disease occurred the previous year. Late blight can overwinter in volunteers or cull piles.

"You only need a spark to start a fire," Nolte said.

Idaho has had relatively little experience with late blight. An outbreak in 1995 caused a lot of crop damage in Western Idaho and another in 1997 slammed several fields in south-central Idaho, Nolte said.

Another widespread outbreak occurred in 1998, but remained at low levels, he said. Since then, the disease has kept a low profile, but that could change at any time, Nolte said.

Better reporting of the disease could help limit the damage from the next outbreak, he said.

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