Evaluation of Chipped Cankers for Management of Eastern Filbert Blight

Oregon harvested 36,000 tons of hazelnuts with a farm gate value of $135 million in 2014, primarily from eastern filbert blight (EFB) susceptible cultivars. Cultural management of EFB includes the removing and burning of symptomatic branches to reduce potential sources of inoculum before bud break. As an alternative to burning, chipped cankered branches were studied to determine if they remained a source of inoculum. Branches with or without EFB cankers were coarsely chipped and placed in four piles on the ground at various geospatial locations relative to susceptible host trees. Ascospores were collected above each chipped pile during rain events in the spring of 2012 and 2013. Although ascospore counts were higher above piles containing chipped cankers, they were not significantly different from piles without cankers. However, a small percentage of susceptible hazelnut trees placed amongst, upwind, or downwind of these piles and exposed to ascospores developed EFB cankers. It is advised that when not burning cankered branches, growers should chip these branches prior to bud break in the spring to reduce the risk of potential exposure of the orchard to ascospores.