Rhabdocline pseudotsugae

Taxobox
name = "Rhabdocline pseudotsugae"
regnum = Fungi
phylum = Ascomycota
classis = Leotiomycetes
subclassis = Leotiomycetidae
ordo = Helotiales
familia = Hemiphacidiaceae
genus = "Rhabdocline"
species = "R. pseudotsugae"
binomial = "Rhabdocline pseudotsugae"
binomial_authority = Syd., (1922)
synonyms = "Rhabdocline pseudotsugae subsp. epiphylla" A.K. Parker & J. Reid, (1969)
"Rhabdocline pseudotsugae subsp. pseudotsugae" Syd., (1922)

"Rhabdocline pseudotsugae" is a fungal plant pathogen. The pathogen, along with "Rhabdocline weirii" causes Rhabdocline needlecast; "R. weirii" only affects Douglas-fir trees. The disease causes the needles of the tree to discolor and eventually fall from the tree. It was originally common to the Rocky Mountain states of the United States but has since spread to Europe. Infections usually start in the spring or early summer and can change the color of the foliage to a variety of hues. The fungus produces apothecia that are normally found on the underside of needles but they also occur on the topside as well.

Range

Originally common in the Rocky Mountain States, the fungi spread to the Northeastern United States on ornamental forms of fir trees planted there. It has spread to Europe on trees imported from western North America and it is causing problems with trees growing there also. Westcott, Cynthia, and R. Kenneth Horst. 1979. "Westcott's Plant disease handbook". New York: Van Nostrand Reinhold. Page 250. ISBN 0-442-23543-7 ]

Infection

New infections start in the spring or early summer and conditions that cause prolonged needle wetness promote heaver outbreaks.Hagle, Susan K., et al., "A Field Guide to Diseases & Insect Pests of Northern & Central Rocky Mountain Conifers", " [http://www.fs.fed.us/r1-r4/spf/fhp/field_guide/112rhbdnc.htm Rhabdocline Needle Cast] ,"United States Forest Service, 2003, p. 112. Retrieved 7 September 2007.] The first symptoms produced are small yellow spots on the needle ends that develop in late summer or fall. Normally, by the next spring, the needles have started to turn reddish-brown in color produced in mottled or banded patterns. If the infection is severe then needles will turn solid brownish-red and the entire tree will have a "scorched" look to it.

The pathogen, along with "Rhabdocline weirii" causes Rhabdocline needlecast; "R. weirii" only affects Douglas-fir trees." [http://www.na.fs.fed.us/spfo/pubs/howtos/ht_df-ndlcst/ndlcst.htm How To Identify and Control Rhabdocline and Swiss Needlecasts of Douglas-Fir] ," North Central ForestExperiment Station "United States Forest Service", 1983. Retrieved 7 September 2007.] The disease causes the needles of the tree to discolor and eventually fall from the tree. The pathogen often makes Douglas-fir trees unsalable as Christmas trees and affects the Christmas tree farming industry." [http://www.plantpath.cornell.edu/trees/RhabdoN.html Rhabodocline Needlecast ("Rhabdocline weirii")] ," Department of Plant Pathology, "Cornell University". Retrieved 7 September 2007.]

The fungus "Rhabdocline pseudotsugae" have apothecia that are normally first produced on the under side of the needles, but it's not uncommon to find them on the top surface too. They are first produced as rounded cushions and as the epidermal layer ruptures, a brown elongated disc is exposed. Needle drop occurs after the ascospores are discharged, normally resulting in only a one year life span for the fungus.

Notes

External links

* [http://www.speciesfungorum.org/Names/Names.asp Index Fungorum]
* [http://nt.ars-grin.gov/fungaldatabases USDA ARS Fungal Database]