Breeding program releases two new potato varieties

By John O’Connell

For Idaho Farm Bureau Federation

ABERDEEN – Chuck Brown admits he suggested Castle Russet as the name of a promising new potato variety originating from his breeding program mostly in tribute to his 3-year-old grandson, who is also named Castle.

The name immediately stuck, however, because of the official explanation Brown offered his colleagues, which is also a key reason why major processors are high on the new spud – like a castle, the variety is a fortress against disease. Castle, which is a medium- to late-maturing variety, has extreme resistance to corky ringspot and all strains of potato virus Y.

Castle was released this spring, along with Echo Russet, by the Tri-State Potato Breeding Program – a cooperative effort involving the potato breeding programs of Idaho, Washington and Oregon.

Brown, who recently retired as potato breeder with USDA’s Agricultural Research Service in Prosser, Wash., made the initial cross for Castle in 2005. The Oregon State University potato breeding program selected Castle from its field trials. Brown describes the variety as good-looking with a heavy russet skin.

“I actually obtained the PVY resistance from a German breeding line that had been developed in Cologne, Germany,” Brown said, adding that breeders are now using Castle heavily as a parent.

PVY, spread by aphids, is one of the most economically important disease of spuds, affecting both quality and yield. Corky ringspot, which is caused by the tobacco rattle virus and spread by stubby-root nematodes, is especially troublesome in sandy soils of the Pacific Northwest, causing up to half of a spud crop to become unmarketable in extreme cases.

Castle also resists potato mop top virus and cold sweetening.

Brown said a couple of major processors have been enthusiastic about Castle, but he also sees potential for the variety in the fresh market. Castle has a uniform shape and size. Though it’s not as long as Russet Burbank – which is still the industry’s standard – Brown said it’s long enough for processors to cut fries.

When Castle is sliced, it doesn’t tend to enzymatically darken, which is another reason why processors like it, Brown said. Castle was among the best varieties tested for producing low levels of acrylamide, which is a chemical formed when certain starchy foods are fried or baked that may be linked to cancer.

During evaluations, Brown said, Castle’s yields posed a concern, but he’s heard no further yield concerns from farmers who have grown it.

Another potential weakness is that the variety has somewhat high levels of glycoalkaloids, which can impart a bitter taste into fries.

Brown said Castle still meets the maximum allowable threshold for glycoalkaloids, and he hasn’t personally noticed any bitterness when sampling it.

Brown said Castle is similar to another recent release from the Tri-State program, called Payette Russet, which is also resistant to several diseases and offers complete PVY resistance. The down side with Payette, he said, has been that it’s known to produce round tubers that don’t produce enough long fries to be economical.

The initial cross for Echo was made in Aberdeen in 1996 by former potato breeder Joe Pavek, who has long since retired. Rich Novy, the current USDA-ARS potato breeder in Aberdeen, explained Echo was selected by OSU for conditions in the Columbia Basin. Its parents were two unnamed breeding clones.

Novy said Echo, like Castle, can be stored for an intermediate period and can be used both for processing or as a fresh variety. It’s a medium- to late-maturing variety with resistance to fusarium dry rot, soft rot and common scab. It also possesses moderate resistance to Verticillium wilt, early blight, PVY, potato leaf roll virus, potato mop top virus and corky ringspot.

“Its primary attribute is a high percentage of marketable yield,” Novy said. “It has very few tuber defects.”

It’s been considered as a good option for organic potato production due to its broad range of disease resistance.

Before the year’s end, Novy said, two more varieties originating from Aberdeen, which have been assigned numbers but are yet to be named, may be released. Novy said A06021 is an early maturing spud with potential in the fresh industry.

The other promising variety, A06336-5Y, is an apricot-colored creamer potato, that produces a high tuber set, a uniform size and has some corky ringspot resistance.

Jeanne Debons, executive director with the Potato Variety Management Institute, which handles licensing and royalty collection of Tri-State varieties, confirmed “some processors are trialing (Castle and Echo) successfully.” Debons said Castle appears to have the most interest.

“I think (Castle) has got potential all over North America,” Debons said. “I’ve had interest already from Canada.”