Rhabdocline pseudotsugae
Encyclopedia
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.
on trees imported from western North America
and it is causing problems with trees growing there also.
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. The pathogen often makes Douglas-fir trees unsalable as Christmas trees and affects the Christmas tree farming industry.
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 ascospore
s are discharged, normally resulting in only a one year life span for the fungus.
Rhabdocline weirii
Rhabdocline weirii is a fungal plant pathogen. The pathogen, along with Rhabdocline pseudotsugae, 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...
causes Rhabdocline needlecast; R. weirii only affects Douglas-fir
Douglas-fir
Douglas-fir is one of the English common names for evergreen coniferous trees of the genus Pseudotsuga in the family Pinaceae. Other common names include Douglas tree, and Oregon pine. There are five species, two in western North America, one in Mexico, and two in eastern Asia...
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
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
but has since spread to Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. Infections usually start in the spring or early summer and can change the color of the foliage to a variety of hues. The fungus
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
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 EuropeEurope
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
on trees imported from western North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and it is causing problems with trees growing there also.
Infection
New infections start in the spring or early summer and conditions that cause prolonged needle wetness promote heaver outbreaks. 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
Rhabdocline weirii
Rhabdocline weirii is a fungal plant pathogen. The pathogen, along with Rhabdocline pseudotsugae, 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...
causes Rhabdocline needlecast; R. weirii
only affects Douglas-fir
Douglas-fir
Douglas-fir is one of the English common names for evergreen coniferous trees of the genus Pseudotsuga in the family Pinaceae. Other common names include Douglas tree, and Oregon pine. There are five species, two in western North America, one in Mexico, and two in eastern Asia...
trees. 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.
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 ascospore
Ascospore
An ascospore is a spore contained in an ascus or that was produced inside an ascus. This kind of spore is specific to fungi classified as ascomycetes ....
s are discharged, normally resulting in only a one year life span for the fungus.