It’s July in northeast Wisconsin. The air is fresh, the birds are chirping, and the potato fields on the isolated seed potato farm in Langlade County are a healthy green. This is a highly-specialized farm where precious disease-free tubers from the state’s elite seed farm are carefully nursed to supply the diverse requirements of commercial growers. Everything on the seed farm seems to be going well this year, and even the eagle-eyed inspectors have not found any evidence of disease. The farmer looks up at the bluebird sky and smiles at the promise of a warm summer day, unaware that a silent enemy may be approaching. In swirls and currents of air coming from the south, a scattering of feather-light insects is alighting unseen on the edges of his fields. They are anxious to insert their needle-sharp mouthparts into the leaves and begin feeding. These are aphids, which act as unwitting flying hypodermics, quietly moving from one plant to the next, sampling the sap they need to live. These harmless creatures are from southern growing areas where a myriad of crops exist that can potentially infect them with any number of virus diseases that they can carry to potatoes. Unlike the July sky, the enemy the aphids carry promises trouble.
Hijackers, tricksters and deceitful agents, plant viruses are some of the most devious and threatening enemies of seed potato growers in North America. They are the number one cause of seed lots failing to meet the standards necessary to wear the Wisconsin Certified Seed label. How do they do it, you ask? Scientists have studied potato viruses for decades. They are very small micro-organisms that can enter plant cells with the aid of vectors, such as the aphids, but are incapable of multiplying without the help of the potato host’s resources. Once inside a cell, virus particles use different strategies to hijack the cell’s resources to make more copies of themselves. Plants, like humans and other organisms, have defense systems that will recognize the presence of an enemy and try to stop its attack. But some viruses, like Potato virus Y, counterattack by turning off, or ‘silencing’ the plant’s defenses, allowing them to keep using the plant’s resources to multiply. (more…)
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…)
When you think about how to use new advances in X-ray technology, potato breeding is probably not the first thing that springs to mind. However, scientific researchers at the University of Wisconsin are doing just that to help develop new potato varieties — and to do it faster! State-of-the art, high- speed X-ray technology is now becoming a routine practice for evaluating potential new potato varieties, because it is faster and much more effective. Do you remember your last X-ray at the doctor office? It was time-consuming, uncomfortable and expensive. Not so with potatoes! Every day during harvest, tens of thousands of potatoes are examined in just milliseconds, at virtually no cost!
This technology is possible by incorporating a high speed X-ray imager into the potato-grading line (where potatoes are evaluated after harvest). This imager takes an X-ray image of each tuber as it passes through the machine at a high rate of speed. From that image, computers calculate just about anything that you ever wanted to know about that tuber, including its weight, length, width, height and shape; most remarkably, it can determine if there are defects on the outside and even the inside of the tuber. This is a huge improvement on previous technology in both speed and expense, which is akin to doctors being able to take the X-rays they need as you drive past the clinic! (more…)
This is a wonderful time of year when winter grudgingly gives way to spring and our next growing season. From my third story office windows in Antigo I have the opportunity to see trucks hauling seed potatoes from our seed farms in northern Wisconsin to our commercial farms in the Central Sands and beyond. This flurry of activity lasts for several weeks as farms take in, cut, treat, suberize and warm the seed in preparation for planting. Like many things in Wisconsin, potatoes can be very unique. We have a multitude of types and varieties to choose from. These types and varieties are very specific in their purpose. Certain types are better for certain uses. There are many russet varieties, some have cooking characteristics for home and restaurant use, we call fresh or table potatoes. While other russets, are best suited for frying (process / frozen). (more…)
The Central Sands is one of the nation’s premier potato and vegetable production areas, ranking 3rd in potatoes, 1st in snap beans and 3rd in sweet corn. Agriculture in the Central Sands is vital to Wisconsin’s economy, generating over $6.4 billion in revenue and providing 35,000 jobs. This agricultural bounty is possible because of the area’s broad expanse of fertile soils (developed as a result of retreating glaciers over 10,000 years ago), by our mild temperate climate, from the hard work and dedication of the farmers who settled, manage and continue to operate on the landscape and ultimately, the groundwater. (more…)