Silver leaf is a

fungal A fungus ( : fungi or funguses) is any member of the 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, separately from th ...

disease of

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

s 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 ''Prunus'' is a genus of trees and shrubs, which includes (among many others) the fruits plums, cherries, peaches, nectarines, apricots, and almonds. Native to the North American temperate regions, the neotropics of South America, and the p ...

''. 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. 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 An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...

and

pear Pears are fruits produced and consumed around the world, growing on a tree and harvested in the Northern Hemisphere in late summer into October. The pear tree and shrub are a species of genus ''Pyrus'' , in the family Rosaceae, bearing the p ...

s. 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 ''Stereum'' is the type genus of the Stereaceae family of fungi, in the Russulales order. Until recently, the genus was classified in the Corticiaceae family, of the Corticiales order. However, it was given its own family as a result of the spl ...

'', 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 The Russulales are an order (biology), order of the Agaricomycetes, (which include the agaric genera ''Russula'' and ''Lactarius (fungus), Lactarius'' and their polypore, polyporoid and corticioid relatives). According to the ''Dictionary of the ...

''.

Characteristics

It is a pathogen of various deciduous trees including species of '' Acer'', ''

Aesculus The genus ''Aesculus'' ( or ), with species called buckeye and horse chestnut, comprises 13–19 species of flowering plants in the family Sapindaceae. They are trees and shrubs native plant, native to the temperateness, temperate Northern H ...

'', ''

Alnus Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few sp ...

'', ''

Betula 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 3 ...

'', ''

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 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 ...

'', ''

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 ''Malus'' ( or ) is a genus of about 30–55 species of small deciduous trees or shrubs in the family Rosaceae, including the domesticated orchard apple, crab apples, wild apples, and rainberries. The genus is native to the temperate zone of th ...

'', ''

Ostrya ''Ostrya'' is a genus of eight to 10 small deciduous trees belonging to the birch family Betulaceae. Common names include hop-hornbeam and hophornbeam. It may also be called ironwood, a name shared with a number of other plants. The genus is na ...

'', ''

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 ...

'', ''

Salix Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist so ...

'', and ''

Sorbus ''Sorbus'' is a genus of over 100 species of trees and shrubs in the rose family, Rosaceae. Species of ''Sorbus'' (''s.l.'') are commonly known as whitebeam, rowan ( mountain-ash) and service tree. The exact number of species is disputed depend ...

''. 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) and are covered with whitish hairs. After a week or two the fructification dries out, becomes brittle, and turns a drab brown or beige.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 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 ...

with

clamp connection A clamp connection is a hook-like structure formed by growing hyphal cells of certain fungi. It is a characteristic feature of Basidiomycetes fungi. It is created to ensure that each cell, or segment of hypha separated by septa (cross walls), rece ...

s. It is often found on old stumps and dead wood, but can also be a serious

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

of living trees. As well as plum trees it attacks many other broad-leafed species (other ''

'',

apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...

willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist s ...

, poplar,

maple ''Acer'' () is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since http ...

hornbeam Hornbeams are hardwood trees in the flowering plant genus ''Carpinus'' in the birch family Betulaceae. The 30–40 species occur across much of the temperate regions of the Northern Hemisphere. Origin of names The common English name ''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' ...

oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...

elm Elms are deciduous and semi-deciduous trees comprising the flowering plant genus ''Ulmus'' in the plant family Ulmaceae. They are distributed over most of the Northern Hemisphere, inhabiting the temperate and tropical-montane regions of North ...

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,

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 ''Thuja'' ( ) is a genus of coniferous tree or shrub in the Cupressaceae (cypress family). There are five species in the genus, two native to North America and three native to eastern Asia. The genus is monophyletic and sister to ''Thujopsis''. M ...

'', ...). 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

aspen Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section ''Populus'', of the ''Populus'' genus. Species These species are called aspens: *'' Populus adenopoda'' – Chinese aspen (China ...

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,

s, pin cherry, 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 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 ''Alnus rubra'', the red alder, is a deciduous broadleaf tree native to western North America (Alaska, Yukon, British Columbia, Washington, Oregon, California, Idaho and Montana). Description Red alder is the largest species of alder in Nort ...

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'' is similar, and usually has moss covering its cap.

References

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

Characteristics

Mycoherbicide

Similar species

References

Further reading

External links