Taking a crack at hazelnut production

Thursday, February 23, 2017

Eastern filbert blight: A history

By Nicholas Van Allen

For many years, hazelnut farming has been confined to the Pacific Northwest – in places like Oregon, Washington State and British Columbia. But, with grower trials now underway in Ontario and new science, Ontario's hazelnut growers are on the cusp of major industry expansion.

In many ways, the evolution of hazelnut farming has been shaped by the presence of the eastern filbert blight, a canker disease which infects hazelnut trees.

Andrew Fuller, author of The Nut Culturist, a turn-of-the-twentieth-century American textbook on nut cultivation, wrote that he had witnessed the devastating effects of the eastern filbert blight in the mid- to late-nineteenth century.

He first attempted to grow hazelnuts on a small scale in the early 1860s and he had a crop within just a few years.

Fuller wrote positively of the hazelnut in the text, saying that, "In my own experience I have found no other nut tree … that has been more satisfactory. The plants come forward rapidly, fruiting freely and abundantly when young, and if properly trained, the crop can be gathered with little labor."

Despite this success, he also "noticed that an occasional shoot was affected with blight." And the year following, he saw that "more of the branches were affected, and from these the blight extended downward on the main stems."

Shortly after this observation, Fuller said that he knew his trees "were doomed."

The only method for controlling the blight was to "cut and burn the discarded stems" of affected hazelnut trees but this proved to not be enough for a curious breeder like Fuller.

While the blight does not kill trees immediately, since their roots remain and continue to send up new shoots, the disease renders plants unproductive within two or three years of initial infection.

North American varieties of hazelnut experience only insignificant cankers from the disease, according to a paper published in Plant Disease. European hazelnuts, in contrast, which produce fruit more suitable for production and processing, are seriously affected. "Expanding cankers girdle branches and limbs, resulting in canopy dieback … and death of trees in 5 to 12 years if diseased limbs are not removed," the study said.

Fuller's hazelnut trees were a European variety, having been brought to the United States from the United Kingdom. He remained convinced that the blight was what prevented widespread cultivation of hazelnuts in the United States east of the Rocky Mountains.

Over the next century, the Rockies remained a barrier to the spread of the eastern filbert blight. Hazelnut cultivation grew in the Pacific Northwest, Oregon and Washington in particular.

By the early 1970s, though, the blight was observed in western Washington State, having spread unnoticed in the late-1950s and 1960s.

In the 1980s, in order to save the northwestern hazelnut production from the blight, government and industry-supported research efforts began in earnest and they continue to this day.

    Photo credit: Ontario Hazelnut Association photo

Thankfully, eastern filbert blight is a geographically slow-spreading disease, something which has given researchers time to conduct studies and adapt varieties in order to support continued hazelnut agriculture.

Today, efforts at research stations like the one in Simcoe, supported by the Ontario Ministry of Agriculture, Food and Rural Affairs and the University of Guelph, are developing productive, disease-resistant varieties. BF