Knowing Your Roots

Archive for November, 2014

How do potatoes get to your holiday table? – It all begins with the seed!

Blog 7

Potatoes, we love them, particularly at this time of year. Thanksgiving is close, and it just would not be the same without those creamy mashed potatoes to accompany your turkey and cranberries. Did you know that Wisconsin ranks 3rd in US potato production?  Did you know that the potatoes you are enjoying actually began life anywhere from 5-8 years before they got to your plate?  Probably not, but during the next few blog posts we would like to introduce you the exciting journey that your potato takes from a lab in Madison, to isolated farms in pristine Northwest Wisconsin and even a trip to Hawaii for a lucky few. This is the process needed to produce the disease-free seed tubers that potato growers must plant to meet all your culinary potato needs.  We hope these next blog posts will help illuminate this fascinating journey.

Potatoes are not grown from actual seeds, but come from daughter tubers (seed pieces) that carry all the traits of the mother plant. To be certain that plants are disease-free, true to variety and carry only the traits such as color, texture and taste that consumers desire, the journey starts in labs on the University of Wisconsin-Madison campus.  The Wisconsin Seed Potato Improvement Program, the first of its kind in the US, is funded by Wisconsin potato growers and directed  by Dr. Amy Charkowski of the UW-Department of Plant Pathology. Here, disease-free potato plants representing hundreds of varieties and characteristics are maintained. In the winter, tiny tissue slivers are grown into small plants in sterile test tubes. These tiny plants, the forerunners of your favorite baked or mashed potato, are then cut into even smaller pieces and grown into plantlets that have roots and leaves of their own.  Every spring, thousands of these plantlets are driven from Madison to an isolated UW Elite Seed farm in northern Wisconsin, close to Rhinelander. Once there, they are placed in protected hydroponic greenhouses, where they can grow over the summer and produce hundreds of pea to marble-sized mini-tubers, which represent the future of the potato industry. Over 400,000 mini-tubers are produced in Wisconsin using this method every year.   (more…)

Band Aids® won’t help these potatoes?

Blog 6

Like humans, potatoes develop scabs. Although they look similar – raised, rough, brown growth on the surface of the skin – they are fundamentally different. The scabs you got when you scraped your knee as a child are part of the human body’s natural healing process. When the scab finally falls away, new, unblemished skin is left underneath. In contrast, potato scabs are a disease that infect the tuber skin; these scabs don’t heal and can even get worse as the disease progresses.  A better name would be “potato ulcers.”  Ulcers are open wounds that are slow to heal, originally thought to be caused by factors such as stress or skin irritation but later, were shown to actually be caused by bacteria.

Potato common scab is caused mainly by the bacterium Streptomyces scabies. The scabs produced by these bacteria are largely cosmetic and limited to the surface of tubers, but they drastically reduce marketability and are rated as one of the top 5 potato diseases in the U.S. Common methods of controlling infection – using pesticides and increasing irrigation – are expensive and often ineffective. In organic production, scab can be the major cause of tuber rejection. This is a classic example where breeding a potato with natural immunity to common scab is the most effective and perhaps the only realistic approach to managing this serious disease threat. There are currently no varieties of cultivated potato that are immune to common scab, but wild potato species offer a wealth of genetic diversity and have long been viewed as a potential source of desired traits such as disease resistance. Researchers at the UW-Madison have identified a line of the wild potato species Solanum chacoense from South America that is highly resistant to common scab and a closely related line that is susceptible.    (more…)

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