Eliminating scab from your spuds

Potatoes are stored in brown paper bags and labeled for next year’s planting. The key is to keep them cool and dark.(Marion Owen photo)

This week’s main topic is potatoes. My friend Natasha, who provided the recipe for Kremlin salad in last week’s column, has a unique relationship with potatoes. While in Moscow, studying to be a doctor, she — and every other student — was required to spend one month every summer working in the fields.

For Natasha, it meant four weeks of harvesting potatoes — back-breaking, leg-staining work.

Natasha eventually moved to Arizona, continued her practice and has been retired for several years now. But this summer, when she helped me harvest our potatoes, the experience was fresh in her mind.

“Digging potatoes was much better than harvesting cabbage, which could be really stinky,” she said. “And there was a lot more vodka drinking associated with working in the cabbage fields.”

Back to our garden in Kodiak. I gave the wilted potato stalks a tug with one hand, and with the other I pushed the potato fork down into the soil against the inside wall of the raised bed. As I pulled back on the handle to (hopefully) lift a few potatoes from their grip to the soil, I heard Natasha grumble softly under her breath.

“Don’t lift too much or you’ll damage dem,” she said. “Just do it a leetle beet and then reach in to pull dem out.”

I followed her lead and in 20 minutes we’d cleared out the bed, leaving the potatoes on top of the soil for inspection. All but one variety was scab free, which pleased me to no end because I’d done a ton of research prior to sending in my order to Fedco Seeds (www.fedcoseeds.com) for their certified, disease-free potatoes.

Here are the best, scab-free potato varieties that we grew this year:

Satina: Early to midseason maturity, yellow skin color and flesh color, moist, crunchy, and firm; stores well.

Keuka Gold: Midseason, creamy buff skin color, light yellow inside, moist and firm, good storage qualities.

Elba: Late season, buff outside and light yellow outside, moist and firm, a good keeper.

Russet Burbank: Very late maturity, russet-brown skin color and white flesh color; a little on the dry side, excellent keeper.

Butte: Late season maturity, medium russet colored skin and white flesh; dry texture, excellent storage qualities.

I selected several pounds of each variety and set them aside for next year’s planting by placing them in brown bags. I’ll keep them over the winter in the “cold room,” an unheated space off the kitchen.

In addition to learning what I could about scab-resistant potatoes, I’d also paid careful attention to preparing the soil, making sure that I didn’t add too fresh a compost or manure, or turn in any wood ashes, because scab often forms on potatoes grown in soil that is too sweet, that is, with too high a pH.

Normally I don’t fuss this much about potatoes (or moose tubers, as the folks at Fedco call them), except that a visit last year with Jeff Smeenk, the potato expert (would that make him Mr. Potato Head?) at the Palmer Research and Extension Center, prompted me to do what I could to reduce the chances of my spuds developing scab.

Common potato scab is a tuber disease that occurs throughout the potato growing regions of the world. It is caused by the microorganism called S. scabies, which is present in almost all soils, and flares up when the soil pH rises above a value of 5.2. The scab lesions develop on the skin of the potato and while it doesn’t affect its eating qualities, affected spuds do not store well.

So, as I’ve learned over the years, rotating crops and soil preparation isn’t always the end-all solution to scab, and trying to figure out why it would appear in one part of a raised bed and not another would be very frustrating, to say the least. I was determined to find a solution. So when Jeff said, “Using resistant varieties is an effective tool for management of scab,” I jumped on it.

Another issue that affects potato-growing efforts in Kodiak is our damp summers. And this last one was definitely on the wet side. Turns out that soil moisture (generally, the extremes of too dry or too wet) during tuber formation has a dramatic effect on common scab infection.

“There are very few ‘free lunches’ in the ecosystem,” Jeff told me, adding that dealing with all the variables are just some of the management decisions that the gardener has to make.

“On the bright side,” added Jeff, “we do not have the Colorado potato beetle. Continue to cross your fingers.”

Question of the week

What temperature should the water be when watering houseplants?

Anchorage gardener Jeff Lowenfels likes to fall back on the Goldilocks rule: Not too hot and not too cold. Thus, room temperature is a good place to start. So what’s wrong with cold or hot water?

Water is one of the critical highways that moves nutrients and holds oxygen that is necessary for plant root growth as well as the life of the aerobic community (the friendly little critters) in soil.

“Hot water holds less oxygen and the heat can physically disrupt the all-important, root zone, microbial balance,” said Jeff, coauthor of “Teaming With Microbes: A Gardener’s Guide to the soil food Web.”

“Water that is too warm may even damage the delicate cell walls of new root hairs that absorb the bulk of nutrients,” he said.

Cold water, on the other hand, can shock room temperature microbes and cause roots to actually go dormant.

Since room temperature is best, prepare a batch of water by leaving a pitcher, watering can or bucket filled with water to adjust to room temperature.

“Sitting longer than 24 hours, this water will also release any chlorine in the water, an act the microbiology in houseplant soil will appreciate.”

Above everything else, however, is not to overwater houseplants during the winter months. Most plants do best when the soil dries out a bit in between watering.

Meanwhile, enjoy — and appreciate — those potatoes.

Marion Owen can be reached at mygarden@alaska.net.

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