Plant Disease Management Handbook

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Hazelnut Cultivar Susceptibility

Eastern filbert blight showing dark, sunken canker and black fungal stroma.

Jay W. Pscheidt, 2007.

This branch has been girdled causing the leaves beyond the canker to die.

Jay Pscheidt, 2006.

This heavily infected orchard has many dead and dying branches.

Jay W. Pscheidt, 2007.

'Jefferson' hazelnut with EFB. Note that there are no stroma but there is perennial infection of the trunk.

Jay W. Pscheidt, 2013.

This Turkish hazelnut (Corylus colurna) has classic EFB symptoms.

Jay W. Pscheidt, 2016.

Note the black stroma within the sunken canker.

Photo by Jay W. Pscheidt, 1990.

Cause Unknown. No investigations have been reported. The cultivar Barcelona tends to show it more than other cultivars, but it is on fewer than 5% of the catkins. The cultivar Yamhill routinely has catkins with kinks and brown tips. The problem is widespread throughout the Willamette Valley in Oregon and has been found in British Columbia. No adverse yield effects have been linked to this problem. Although the big bud mite will blast open dormant buds, no mites have been associated with these deformed catkins.

Deformed catkins where part of the catkin prematurely opens in late summer.

Jay W. Pscheidt.

Note the bent and swollen catkin.

Photo by Jay W. Pscheidt, 1994.

Cause Unknown. Possibly a physiologic problem because no insects or pathogens have been associated with this problem. Severity of the problem changes from year to year.

Note the brown, discolored tissue that extends between the vascular system of the shell.

Photo by Jay W. Pscheidt, 1997

Image related to Hazelnut (Corylus avellana)-Brown Stain

Brown droplets may be observed on the nut and/or husk.

Photo by Harry Lagerstedt, 1969. (Jeff Olsen collection)

Cause The official definition of blanks is a shell containing no kernel at all or a kernel filling less than one-fourth the capacity of the shell. Pollination stimulates the shell to develop, but the kernel, for unknown reasons, fails to develop normally. The kernel either fails to grow at all, or it starts to grow but then aborts. Pollination failure is not the cause; if pollination had failed, the shell would not have developed at all.

When cracked open, blank nuts have no kernel as the one on the top left does. Various blemishes can be seen on the outside shell of blanks.

Jay W. Pscheidt, 2007.

Nuts on the ground here have fallen early before the main crop and will be ground up before harvest.

Jay W. Pscheidt, 2007.

Pollination stimulates the shell to develop, but the kernel fails to develop.

OSU Plant Clinic, 2022.

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Hazelnut Cultivar Susceptibility

Trees seem to die randomly in the orchard during the summer.

Jay W. Pscheidt, 2010.

Exposed, discolored cambium originating from the top of the tree.

Photo by Jay W. Pscheidt, 1991.

Image related to Hazelnut (Corylus avellana)-Bacterial Blight

Notice the discolored cambium exposed in this picture of bacterial blight on an older tree. The canker does not go below soil line.

Photo by Jay W. Pscheidt, 1989.

Leaf spot due to bacterial blight.

OSU Plant Clinic Collection, 2011.

Branch and bud dieback due to bacterial blight.

Larry Moore collection, 1970.

Leaf spots due to bacterial blight.

Larry Moore collection, 1969.

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Cherry (Prunus spp.) - Armillaria Crown and Root Rot

Image related to Hazelnut (Corylus avellana)-Armillaria Root Rot

Symptoms above ground are not specific and include a general decline.

Steve Renquest, 2012.

Mycelial fans can be seen when the bark is cut or peeled back.

Steve Renquest, 2012.

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Crabapple (Malus spp.) - Scab

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Juniper (Juniperus spp.) - Rust

Rust infection on the top side of the leaf (right side of image) can be subtle while structures produced on the lower leaf surface (left side of image) or fruit are obvious.

Jay W. Pscheidt, 2019.