Forest & Grassland Health

Spruce/Gemmamyces Bud Blight

Gemmamyces piceae (Borthw.) Casagr.

Host(s) in Alaska:

Sitka spruce (Picea sitchensis)
white spruce (P. glauca)
black spruce (P. mariana)
Colorado blue spruce (P. pungens); ornamental

Habitat(s): Buds, twigs


Photos

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Fruiting bodies of Gemmamyces piceae on white spruce near Anchorage, AK.

Fruiting bodies of Gemmamyces piceae on white spruce near Anchorage, AK.

Black, swollen, and misshapen buds with fruiting bodies of Gemmamyces piceae on white spruce near An

Black, swollen, and misshapen buds with fruiting bodies of Gemmamyces piceae on white spruce near Anchorage, AK.

Deranged growth caused by Gemmamyces piceae on white spruce near Anchorage, AK.

Deranged growth caused by Gemmamyces piceae on white spruce near Anchorage, AK.

Deranged growth of ornamental Colorado blue spruce caused by Gemmamyces piceae near Homer, AK

Deranged growth of ornamental Colorado blue spruce cased by Gemmamyces piceae near Homer, AK.

 

Current Status & Distribution in Alaska (updated March 2017)

Spruce bud blight was first detected on a Colorado blue spruce ornamental near Homer in 2013, although it remained unidentified until 2016. As of 2016, the pathogen has been documented at several locations near Anchorage (Far North Bicentennial Park, Little Campbell Lake, and Kincaid Park), seven locations on the northern and western Kenai Peninsula (near Hope, Kenai, Clam Gulch, Ninilchik, Anchor Point, Homer, and Kachemak City), and one location in Fairbanks west of the University of Alaska campus. In the forest, white, Sitka, and black spruce have been affected, and Colorado blue spruce in ornamental settings. Forest Health Protection began installing monitoring plots at these known locations in 2016. Preliminary analysis found that damaged buds affected up to 40% of the trees within plots. Most trees that have the disease have very few damaged buds (less than 5%), but highly infected trees can have up to 100% of the buds dead or damaged. Mortality in Alaska has not yet been attributed to this disease. However, because the pathogen favors cold temperatures, close monitoring is critical. An intensive, plot-based, combined spruce bud blight and spruce aphid detection and monitoring survey will commence in 2017.

Historic Activity

Identification of this disease by Forest Health Protection in Alaska became possible with a 2016 publication reporting a sudden outbreak in Colorado blue spruce plantations in the Czech Republic1. The publication describes a recent, massive outbreak that was first detected in 2009 and has now been found across the Czech Republic. Bud loss could quickly reach 80-100% in highly infected trees and stands. The fungus has been reported since 1906 from Austria, Czech Republic, Denmark, Finland, Russia, Scotland, and Switzerland2. In these locations, it has primarily been found in human-altered situations (e.g., urban ornamentals, nurseries, and forest plantations) on the North American tree hosts Colorado blue spruce and Engelmann spruce, but Sitka spruce and white spruce were also susceptible to a lesser degree. Neither the fungus, nor the disease it causes, were found within the native range of Norway spruce in Europe until 1946. It has been speculated that the fungus is native to Asian spruce from the Tianshan Mountains in China1. However, a recent paper made an apparently unsupported claim that it is widespread in North America3.

Symptoms, Biology & Impacts

The disease is recognized by black, swollen, misshapen buds and deranged growth patterns. Frequently buds are killed by the pathogen prior to bud break. Infected shoots that are not killed, characteristically twist around developing lesions. Blighted terminal buds lead to axillary bud proliferation and dominance resulting in zigzag growth patterns. After several years of bud loss, trees may wither and die.

Survey Method & Frequency

Observations are periodically made during field inspections, though little targeted survey exists. An intensive, plot-based, combined spruce bud blight and spruce aphid detection and monitoring survey will commence in 2017.

Distribution Map

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Locations where spruce bud blight (Gemmamyces piceae) has been found in ground surveys (2014-2017).

Current known distribution of Gemmamyces piceae in Alaska showing a partial distribution of the spruce host (Picea spp.) (July 2017). Modeled spruce distribution was developed by the Forest Health Technology Enterprise Team in 2011 (240m-resolution, based on dominant tree species by tree diameter).

 

Links to Resources & Publications

1 Černý, K., Pešková, V., Soukup, F., Havrdová, L., Strnadová, V., Zahradník, D., & Hrabetová, M. 2016. Gemmamyces bud blight of Picea pungens: A sudden disease outbreak in central Europe. Plant Pathology, 65(8): 1267-1278.

2 Borthwick A.W. 1909. A new disease of Picea. Notes from the Royal Botanic Garden, Edinburgh, 4: 259–61.

3 Jaklitsch W.M. & Voglmayr H. 2017. Three former taxa of Cucurbitaria and considerations on Petrakia in the Melanommataceae. Sydowia 69: 81–95.

Forest Health Conditions in Alaska - 2016

Global Diversity Information Facility - Gemmamyces piceae

USDA National Fungus Collection Database - Gemmamyces piceae

 

Content prepared by Lori Winton, PhD Forest Pathologist, Forest Health Protection, lmwinton@fs.fed.us

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