Silver leaf is a
fungal disease of
trees caused by the fungus plant pathogen ''Chondrostereum purpureum''. It attacks most species of the rose family
Rosaceae
Rosaceae (), the rose family, is a medium-sized family of flowering plants that includes 4,828 known species in 91 genera.
The name is derived from the type genus ''Rosa''. Among the most species-rich genera are ''Alchemilla'' (270), ''Sorbus ...
, particularly the genus ''
Prunus''. The disease is progressive and often fatal. The common name is taken from the progressive silvering of leaves on affected branches. It is spread by airborne
spore
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...
s landing on freshly exposed
sapwood
Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin t ...
. For this reason
cherries
A cherry is the fruit of many plants of the genus ''Prunus'', and is a fleshy drupe (stone fruit).
Commercial cherries are obtained from cultivars of several species, such as the sweet ''Prunus avium'' and the sour ''Prunus cerasus''. The nam ...
and
plum
A plum is a fruit of some species in ''Prunus'' subg. ''Prunus'.'' Dried plums are called prunes.
History
Plums may have been one of the first fruits domesticated by humans. Three of the most abundantly cultivated species are not found i ...
s are pruned in summer, when spores are least likely to be present and when disease is visible. Silver Leaf can also happen on
poming fruits like
apples and
pears. Plums are especially vulnerable.
[Entry "Silver-leaf Fungus" in Phillips, Roger (1981) "Mushrooms and other fungi of Great Britain & Europe" published by Pan Books Ltd., Cavaye Place, London SW10 9PG (ref. CN1794)]
In the past the name ''Stereum purpureum'' Pers. was widely used for this fungus, but according to modern taxonomy it is only distantly related to ''
Stereum'', actually belonging to order
Agaricales
The fungal order Agaricales, also known as gilled mushrooms (for their distinctive gills) or euagarics, contains some of the most familiar types of mushrooms. The order has 33 extant families, 413 genera, and over 13,000 described species, alo ...
whereas ''Stereum'' is in order ''
Russulales''.
Characteristics
It is a pathogen of various deciduous trees including species of ''
Acer'', ''
Aesculus'', ''
Alnus'', ''
Betula'', ''
Crataegus
''Crataegus'' (), commonly called hawthorn, quickthorn, thornapple, Voss, E. G. 1985. ''Michigan Flora: A guide to the identification and occurrence of the native and naturalized seed-plants of the state. Part II: Dicots (Saururaceae–Cornacea ...
'', ''
Fagus'', ''
Larix
Larches are deciduous conifers in the genus ''Larix'', of the family Pinaceae (subfamily Laricoideae). Growing from tall, they are native to much of the cooler temperate northern hemisphere, on lowlands in the north and high on mountains furth ...
'', ''
Malus'', ''
Ostrya'', ''
Picea
A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfami ...
'', ''
Populus
''Populus'' is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar (), aspen, and cottonwood.
The we ...
'', ''
Prunus'', ''
Salix'', and ''
Sorbus''.
[
After starting as just a crust on the wood, the fruiting structure develops undulating intergrowing brackets up to about 3 cm broad, which have a tough rubbery texture. The edges and fertile lower surfaces show a fairly vivid violet colour while the fungus is growing, and the upper surfaces have a grey aspect (sometimes with zonation and usually a lighter edge)][Marcel Bon: ''The Mushrooms and Toadstools of Britain and North-Western Europe'' Hodder & Stoughton .][Courtecuisse, R. & Duhem, B. (1994) "Guide des champignons de France et d'Europe" Delachaux et Niestlé , also available in English.] Infected wood can be recognized because it is stained a darker tint.[
The spores are rounded cylinders approximately 5–8 µm x 3–4 µm in size. The ]hypha
A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium.
Structure
A hypha consists of one or ...
l structure is monomitic with clamp connections.
It is often found on old stumps and dead wood, but can also be a serious parasite of living trees. As well as plum trees it attacks many other broad-leafed species (other '' Prunus'', apple, pear, willow, poplar, maple, hornbeam, plane
Plane(s) most often refers to:
* Aero- or airplane, a powered, fixed-wing aircraft
* Plane (geometry), a flat, 2-dimensional surface
Plane or planes may also refer to:
Biology
* Plane (tree) or ''Platanus'', wetland native plant
* Planes (gen ...
, oak, elm, lilac
''Syringa'' is a genus of 12 currently recognized species of flowering plant, flowering woody plants in the olive family or Oleaceae called lilacs. These lilacs are native to woodland and scrub from southeastern Europe to eastern Asia, and wid ...
, and many others).[Se]
Entry "Silver Leaf Disease"
of Natural Resources Canada (NRCan). Occasionally it also infects conifers (fir
Firs (''Abies'') are a genus of 48–56 species of evergreen coniferous trees in the family (biology), family Pinaceae. They are found on mountains throughout much of North America, North and Central America, Europe, Asia, and North Africa. The ...
, spruce
A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfami ...
, '' Thuja'', ...).[ Geographically it is roughly just as widespread as its hosts; it is common in woods, orchards and tree plantations in temperate climates.
]
Mycoherbicide
''Chondrostereum purpureum'' is commercially available as a method of combatting forest 'weed trees' such as aspens, beech
Beech (''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to temperate Europe, Asia, and North America. Recent classifications recognize 10 to 13 species in two distinct subgenera, ''Engleriana'' and ''Fagus''. The ''Engle ...
, birches
A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus ''Betula'' contains 30 to ...
, maples, pin cherry
''Prunus pensylvanica'', also known as bird cherry, fire cherry, pin cherry, and red cherry, is a North American cherry species in the genus ''Prunus''.
Description
''Prunus pensylvanica'' grows as a shrub or small tree, usually with a straigh ...
, poplars, and other species.[Canadian patent 2451038]
/ref> The fungus is applied directly to the weed trees in a nutrient paste which can be stored and handled conveniently.
The first regulatory approval was granted in 2001 to Myco-Forestis Corporation and targeted species "including birch, pin-cherry, poplar/aspen, red maple, sugar maple, and speckled alder in the Boreal and Mixed forest regions of Canada, east of the Rocky Mountains". It had not been reported as of 2001 to cause any diseases in coniferous
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All extant ...
tree species.[ Compatibility of the Open Government Licence - Canada with Wikimedia projects]
According to a 2007 regulatory decision of the Canadian Pest Management Regulatory Agency
The Pest Management Regulatory Agency (PMRA) is the Canadian government agency responsible for the regulation of pest control products in Canada under the federal authority of the '' Pest Control Products Act'' and Regulations. The agency is a bra ...
, the use of this control method in paste form on Sitka spruce
''Picea sitchensis'', the Sitka spruce, is a large, coniferous, evergreen tree growing to almost tall, with a trunk diameter at breast height that can exceed 5 m (16 ft). It is by far the largest species of spruce and the fifth-larg ...
and red alder will only have a limited impact on non-target trees since the fungal spores are ubiquitous anyway and healthy trees are resistant to attack.
Similar species
''Amylostereum areolatum
''Amylostereum areolatum'' is a species of crust fungus. Originally called ''Thelephora areolata'' in 1828, it was given its current name by French mycologist Jacques Boidin
Ancient and noble French family names, Jacques, Jacq, or James are ...
'' is similar, and usually has moss covering its cap.
References
Further reading
* Strouts, R.G., and T. G. Winter. 2000. ''Diagnosis of ill-health in trees''. Norwich: Stationery Office Books.
External links
Royal Horticultural Society advice on the treatment of infected trees.
{{DEFAULTSORT:Chondrostereum Purpureum
Fungal tree pathogens and diseases
Parasitic fungi
Mycoherbicides
Fungi of Europe
Cyphellaceae
Fungi described in 1794
Taxa named by Christiaan Hendrik Persoon