A spud is born

PRESQUE ISLE, Maine — Greg Porter is the first to say there is no such thing as the perfect potato, but that doesn’t keep him from trying.
For the last eight years, Porter, a professor of agronomy at the University of Maine, has led the potato breeding program at the school, looking for the magical combination of consumer marketability and disease and pest resistance.
Over the years, many tubers were called but few were chosen.
According to Porter, who also has run the university’s agronomic crop management program for 30 years, it can take more than a decade to develop a new potato variety, which begins with a single, tiny seed.
“When you harvest potatoes, what you are actually harvesting is a tuber, or modified stem,” Porter said. “When you plant that tuber as seed for the next crop, what you are actually planting is the vegetative tissue that will produce the very same potato year after year.”
To start the process for an entirely new variety, Porter and his crew look at the actual seeds of the potato plant, which are encased in the above-ground fruiting body of the plant.
“The fruit looks kind of like a mini tomato,” he said. “Each one contains a true seed. From cross-pollination of the seeds, we can develop a new potato variety.”
That process begins under highly controlled conditions in greenhouses and laboratories in Orono and Presque Isle and in cooperation with the Maine Potato Board.
Every spring, Porter’s staff harvests from the greenhouses and plants 50,000 tubers in test plots in Aroostook County, each one representing a different genetic variation of the cross-pollination.
According to Porter, there is no end to the possibilities when it comes to combining different potato DNA.
Much of the early planting is done at the Aroostook Farm’s Maine Agriculture and Forest Experiment Station in Presque Isle.
“We start out with a parent potato with characteristics we like and match it with another parent with other characteristics we like,” he said. “What we hope for is a new potato with desirable traits from both parents. There is a range of characteristics that need to come together to produce something better than you had before.”
That range covers vitamin content, color, flavor, appearance and texture that meet market needs for processors, restaurants, grocery stores or small farm stands.
“The neat thing about potatoes is there are just so many different markets and ways to use new and improved potatoes,” Porter said. “On the one side we try to provide solutions to pests and diseases like late blight, and on the other side we want a potato that farmers and consumers want.”
Porter and his team are devoting a lot of time addressing the problematic “potato virus Y,” which affects seed potato size and yields.
“It’s a challenging issue all across North America,” he said. “We are trying to breed a resistant potato to it and hope to have one in the next two or three years.”
To get there, Porter starts with harvesting those 50,000 potatoes planted annually in Aroostook County.
Of the 50,000, he said, only 2 percent make it to the next round of planting based largely on visual characteristics.
“In the fall we harvest all 50,000 and lay them all out on the ground to make the judgment on which ones get saved,” Porter said. “We look at each one. That can take a couple of weeks.”
The 2 percent that make the cut are planted the following year. Of that batch, he said, maybe 300 will move on to the next round of planting.
The process repeats itself for up to a decade, with more and more of the potatoes being discarded until — if he is lucky — Porter ends up with one to three new, marketable potato varieties.
Along the way, the successful candidates have undergone strict formal tests in laboratories and somewhat more informal taste tests.
“We had three this year that looked really promising with regards to disease and pest resistance,” Porter said. “But they tasted so bad they won’t go on.”
Promising potatoes are sent out to test plots around the country to determine how they grow in other regions and conditions, he said.
Because a new batch of 50,000 potential varieties is planted each year, Porter said there are always new varieties coming along.
“Every year the gene pool marches along,” he said. “On average once every two years we release a new variety.”
In March the Maine Potato Board unveiled the Caribou Russet, a cross between a Silverton Russet and a Reeves Kingpin that produced a potato with good baked and mashed quality for fresh market consumption and for processing into chips.
It joined the Easton and Sebec varieties released about a year ago.
With advances in technology, according to Porter, scientists at Orono are able to use DNA markers to track and select specific traits in the potato.
The entire potato genome has been mapped, he said, and a number of departments at the university are involved in the potato breeding program, including food sciences, plant pathology and entomology.
As soon as Porter and his team are convinced they have a successful variety on their hands, they offer samples to farmers willing to plant and evaluate it.
“They try it out for a few years to see how it works,” he said. “If it looks like the new variety has enough commercial interest, we would recommend its release.”
The Maine Potato Board gets first dibs on any new variety, according to Porter, and can license them to control how and where they are marketed.
“When a variety comes through the system and someone on the user end is really excited about it, that can make the release very significant,” Tim Hobbs, director of development and grower relations with the Maine Potato Board, said. “Some of those varieties can really take off.”
The potato industry is always looking for the next big thing, Hobbs said, and what is desirable can change over time.
“We are always trying to improve the product,” he said. “The breeding program is doing a good job. We are seeing that paying off with new varieties that really have some traction.”
Neither Porter nor Hobbs would admit to having a favorite Maine potato, both saying all varieties have their place in the market. But Porter did say a lot of Eastern and Caribou Russets are being eaten at his house.
Porter is also very excited about an upcoming variety with a red and yellow spotted skin and distinctive kidney bean shape.
“The flesh of that potato is incredibly tasty when roasted,” he said. “We have a few growers trying it now.”
Porter and his team will begin harvesting this season’s 50,000 plants by hand in the coming weeks, and the painstaking culling process begins one more time.
“We try to forget the heartaches of the ones that don’t make it,” he said. “But for the ones that do, you can feel a bit like a proud father.”