Potato growers can do themselves a favor if they keep in mind that their crop will not get better in storage.
Because of that, Phillip Nolte, University of Idaho Extension seed potato specialist, says the biggest influence on how good your crop is coming out of storage, is how you handled it when it went in.
“Probably the most important thing you can do is to avoid damage in harvesting, handling, and loading into storage,” he says.
For example, one of the most feared diseases, Pythium leak, needs a wound to enter the tuber. Usually, it becomes a problem when combined with heat — the disease needs heat to thrive — so warm, dry, chunky soils can damage the spuds.
“That’s a bad disease — it will take out a cellar in a week,” he says. “But diseases are favored greatly by wounding and bruising.”
To avoid the damaging effects of heat, harvest when the pulp temperature is below 60°F. That can mean stopping harvest at about 1 p.m. or 2 p.m., especially if the pulp temperatures are getting too high, says Nolte, no matter how badly you want to finish harvest.
“The guys who run into trouble are the guys who are too eager and want to be the first to get their crop out,” he says.
Another reason it’s critical to store quality potatoes is because today they are often piled high — sometimes as high as 22 feet. With that kind of pressure, you need an extremely clean cellar and great air flow, but even with that, you’ll need a quality crop. If you have potatoes you anticipate might cause a problem, Nolte advises harvesting them last.
A lot of cellars don’t have back doors, so by harvesting them last, you can store them closer to the door. “Always put problem lots in places that can be easily accessed,” he says.
That said, Nolte emphasizes that a cellar is not a hospital. Some lots, he says, should not be brought into the cellar, where they can cause even more problems.
“If they are really a problem, don’t store them at all,” he advises. “Just harvest them and leave them on top of the soil so Mother Nature can go to work on them.”
Keep A Close Eye
Bringing problem potatoes into storage can cause problems for otherwise quality potatoes because you can create “hot spots,” says Nolte.
“Once you get something going bad in storage, even if you’ve got good cooling and air movement, soft rot bacteria can create their own heat — thus the term ‘hot spot,’” he says. “You can end up with a problem that will really take off.”
The upshot is you have to make sure you know exactly what’s going on with your crop, carefully tracking it after harvest.
“Monitor your crop and know what’s in there,” he says, “because once you store it, it’s not going to get better.”
This means that there are times when growers are going to be forced to make tough decisions regarding their crop.
“It all goes back to storage being a hotel not a hospital,” he says. “The longer you hang onto potatoes, the greater the chance for a problem. Sometimes you have to cut your losses and take what you can get now, or you may end up with nothing.”
Editor’s Note: Some of the information for this story is based on a paper authored by Nolte and two University of Idaho Research and Extension colleagues, potato specialist Nora Olsen and potato pathologist Jeff Miller.