At their 104-acre Even Star organic farm in St. Mary’s County, Md., Brett Grohsgal and Christine Bergmark had given up growing potatoes because of nearly invisible hordes of leafhoppers that blow in from the south during March or April, causing the singed-brown leaf tips known as “hopper burn.” Then came Colorado potato beetles, and the two pests often caused complete crop failure.
But potatoes moved back on to Even Star’s planting list, thanks to the special pest-deterrent talents of ‘Prince Hairy,’ a Cornell University-bred variety that didn’t quite make the cut as a high-yielding commercial variety. But Jim Gerritsen, co-owner with his wife, Megan, of Wood Prairie Farm in Bridgewater, Maine, saw the variety’s potential after he read an article about ‘Prince Hairy’ written by Mother Earth News editor in chief Cheryl Long.
“Here was a variety with special appeal to organic growers,” Gerritsen says. He propagated it, and found a good market among pest-plagued gardeners and market growers. In Maryland, Grohsgal found he could grow ‘Prince Hairy’ under heavy pest pressure with only one or two early season sprays of Entrust, a certified organic pesticide.
Four years ago, Walter DeJong, director of Cornell’s potato breeding program, told Gerritsen he thought he had something even better. DeJong had noticed that a particular breeding line was remarkably early and productive for a pest-deterring, hairy-leafed potato, and it was less susceptible to Potato Virus Y than ‘Prince Hairy.’
Gerritsen grew out the sample spuds DeJong gave him, and he liked the taste of the rounded oblong potatoes with tan skin. For three seasons straight, Colorado potato beetles left the plants alone, and the potatoes sized up in less than 90 days — 50 days earlier than ‘Prince Hairy.’ Gerritsen named the new variety ‘King Harry.’
‘King Harry’ (and the earlier ‘Prince Hairy’) are the result of three decades of work by Cornell University potato breeder Bob Plaisted. Starting in the late 1970s, Plaisted began crossing ‘Katahdin’ and other mainstream varieties with Solanum berthaultii, a wild potato from Bolivia. The most successful of these interspecies crosses, including ‘King Harry,’ protect themselves from pests by arming their leaves and stems with hairs filled with sticky fluids. These “trichomes” explode when touched, miring small insects such as leafhoppers and flea beetles in goo. They also ruin the appetites of hungry Colorado potato beetles, reducing or eliminating the need to use other pest control measures.
Grohsgal plans to grow ‘King Harry’ this year for harvesting as a new potato and for storage. ‘King Harry’ seed potatoes are available in limited quantities from Wood Prairie Farm.