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Nothophaeocryptopus gaeumannii
Fruiting bodies of Nothophaeocryptopus gaeumannii
Scientific classification
Kingdom:	Fungi
Division:	Ascomycota
Class:	Dothideomycetes
Order:	Capnodiales
Family:	Mycosphaerellaceae
Genus:	Nothophaeocryptopus
Species:	N. gaeumannii
Binomial name
Nothophaeocryptopus gaeumannii (T.Rohde) Videira, C. Nakash., U. Braun & Crous (2017)
Synonyms
Adelopus gäumanni T.Rohde (1936) Phaeocryptopus gaeumannii Petrak (1938)

Nothophaeocryptopus gaeumannii is a species of fungus that occurs as an endophyte inside the needles of Douglas-fir trees. It is responsible for causing the nonlethal disease known as Swiss needle cast, which results in needle loss and reduction in growth in Douglas-fir.

Traditionally, it has been considered part of family Venturiaceae, but molecular studies have confirmed its placement in Mycosphaerellaceae. Three different lineages of N. gaeumannii are known, each with distinct ecological, morphological, and molecular characteristics.

Distribution

This species of fungus is native to western North America. Remarkably, the disease’s name, Swiss needle cast, arises from the fact that the fungus was first discovered in Switzerland in the 1930s where it was found to be causing disease in plantations of Douglas-fir. It has since been introduced almost everywhere Douglas-fir is grown, and is now widespread in Europe, New Zealand, and Chile. Although the fungus had been known in North America almost since its first discovery, for decades it was not considered to cause disease in its native range, and was largely ignored there until an outbreak occurred in the 1980s and 1990s.

Ecology

N. gaeumannii is an obligate endophyte of Douglas-fir needles. In the spring, ascospores infect young needles, briefly growing epiphytically before the hyphae penetrate the needle tissue via stomata. The fungus then spends most of its life cycle growing intercellularly inside the needle. After maturing for approximately nine months, the fungus produces pseudothecia which emerge from the stomata of the needle, dispersing new spores the following spring.

Disease

Normally, when low in abundance, N. gaeumannii is a relatively benign symbiont of Douglas-fir needles. However, when the fungus is abundant it is responsible for causing the nonlethal disease known as Swiss needle cast. It produces small, spherical black fruiting bodies (pseudothecia) which obstruct the needle’s stomatal openings. The pseudothecia block gas exchange into and out of the needle, which prevents photosynthesis in heavily infected needles. This causes yellowing (chlorosis) of the needles, with eventual necrosis and premature needle-drop. In some heavily infected stands of trees, the only needles remaining are those of the current year, in which the disease has not yet had time to fully develop.

Due to the reduced photosynthesis caused by needle loss, the tree experiences a diminished rate of growth by 52% or more. Increased disease severity tends to occur in climates with mild winters and high humidity where the fungus thrives, and appears to be increasing in severity as a result of climate change.

Gallery

References

1. Petrak, Franz (1938). "Beiträge zur Systematik und Phylogenie der Gattung Phaeocryptopus Naumov". Annales Mycologici (in German). 36: 9–26.
2. Rohde T. (1936). "Adelopus gauemannii n. sp. und die von ihm hervorgerunfene "Schweizer" Douglasienschüt". Forst Woch Silva (in German). 24: 420–422.
3. "Swiss needle cast summary". Oregon State University, College of Forestry. Retrieved 2024-12-05.
4. "Nothophaeocryptopus gaeumannii". indexfungorum.org. Retrieved 2024-12-05.
5. Videira, S.I.R.; Groenewald, J.Z.; Nakashima, C.; Braun, U.; Barreto, R.W.; de Wit, P.J.G.M.; Crous, P.W. (2017-06-01). "Mycosphaerellaceae: Chaos or clarity?". Studies in Mycology. 87 (1): 257–421. doi:10.1016/j.simyco.2017.09.003. PMC 5693839. PMID 29180830.
6. Feau, N.; Tanney, J.B.; Herath, P.; Leal, I.; Hamelin, R.C. (2017-06-01). "Genome sequences of three genetic lineages of the fungus Nothophaeocryptopus gaeumannii, the causal agent of Swiss needle cast on Douglas-fir trees". Microbiology Resource Announcements. 13 (2). doi:10.1128/mra.01008-23.
7. "Diseases of Pacific Coast Conifers (No. 521)" (PDF). Forest Service, US Department of Agriculture. Retrieved 2024-12-05.
8. Boyce, J. S. (1940). "A needle-cast of Douglas fir associated with Adelopus gäumanni". Phytopathology. 30 (8): 649–659.
9. Stone, Jeffrey K.; Capitano, Bryan R. & Kerrigan, Julia L. (2008). "The histopathology of Phaeocryptopus gaeumannii on Douglas-fir needles" (PDF). Mycologia. 100 (3): 431–444. doi:10.3852/07-170R1. PMID 18751550. S2CID 808463. Archived (PDF) from the original on 12 January 2014.
10. Manter, D. K.; Bond, B. J.; Kavanagh, K. L.; Rosso, P. H. & Filip, G. M. (2002). "Pseudothecia of Swiss needle cast fungus, "Phaeocryptopus gaeumannii", physically block stomata of Douglas fir, reducing CO2 assimilation". Phytopathology. 148 (3): 481–491. doi:10.1046/j.1469-8137.2000.00779.x.
11. Kimberley, M. O.; Hood, I. A. & Knowles, R. L. (2011). "Impact of Swiss needle-cast on growth of Douglas-fir" (PDF). Phytopathology. 101 (5): 583–593. doi:10.1094/PHYTO-05-10-0129. PMID 20923368. Archived (PDF) from the original on 12 January 2014.
12. Maguire, D. A.; Voelker, W.; Johnson, R. & Johnson, G. (2002). "Growth of young Douglas-fir plantations across a gradient in Swiss needle cast severity". Western Journal of Applied Forestry. 17 (2): 86–95.
13. Watt, Michael S.; Stone, Jeffery K.; Hood, Ian A. & Palmer, David J. (2010). "Predicting the severity of Swiss needle cast on Douglas fir under current and future climate in New Zealand" (PDF). Forest Ecology and Management. 260 (12): 2232–2240. doi:10.1016/j.foreco.2010.09.034. Archived (PDF) from the original on 12 January 2014.
14. Hood, Ian A. (1982). "Phaeocryptopus gaeumannii on Pseudotsuga menziesii in southern British Columbia". New Zealand Journal of Forestry Science. 12 (3): 415–424. Abstract

External links

• "Swiss Needle Cast Cooperative". Oregon State University.

• Venturiaceae
• Fungal conifer pathogens and diseases
• Fungi described in 1936
• Fungi of Europe
• Fungi of North America
• Fungus species