Cypress canker is a disease affecting ''

Cupressus ''Cupressus'' is one of several genera of evergreen conifers within the family Cupressaceae that have the common name cypress; for the others, see cypress. It is considered a polyphyletic group. Based on genetic and morphological analysis, the ge ...

'' species, caused by one of several species of fungus in the genus ''

Seiridium ''Lepteutypa'' is a genus of plant pathogens in the family Amphisphaeriaceae. First described by the Austrian mycologist Franz Petrak in 1923, the genus contains 10 species according to a 2008 estimate. The genus ''Lepteutypa'' is teleomorphi ...

''. Infection causes die-back of twigs and branches in susceptible cypress trees, with rapidly increasing amounts of damage and the death of the tree.

History

The first epidemic of cypress canker was recorded in California in 1928, with

Monterey cypress ''Hesperocyparis macrocarpa'' is a coniferous tree. It is commonly known as the Monterey cypress and is one of several species of cypress trees endemic to California. The Monterey cypress is found naturally only on the Central Coast of Califor ...

(''Cupressus macrocarpa'') being affected. Within a few years the local populations of this tree had been killed. The species is widely traded as an ornamental tree and the disease had soon spread worldwide, probably with nursery stock. Within five decades the disease had reached New Zealand, France, Chile, Italy, Argentina, Greece, most of Europe, Canada, North Africa, South Africa and Australia. The causal agent of this

pandemic A pandemic () is an epidemic of an infectious disease that has spread across a large region, for instance multiple continents or worldwide, affecting a substantial number of individuals. A widespread endemic (epidemiology), endemic disease wi ...

spread was the pathogenic fungus ''

Seiridium cardinale ''Seiridium cardinale'' is a species of fungus. It is the primary cause of Cypress canker Cypress canker is a disease affecting ''Cupressus'' species, caused by one of several species of fungus in the genus ''Seiridium''. Infection causes die ...

'', with '' Seiridium cupressi'' and '' Seiridium unicorne'' sometimes being involved, but being less aggressive; other pathogenic fungi can also cause cankers in cypresses.

Hosts

Besides Monterey cypress, other trees attacked by the fungi that cause this canker include ''

Cupressus sempervirens ''Cupressus sempervirens'', the Mediterranean cypress (also known as Italian cypress, Tuscan cypress, Persian cypress, or pencil pine), is a species of cypress native to the eastern Mediterranean region, in northeast Libya, southern Albania, sou ...

'', ''

Cupressus pigmaea ''Cupressus pigmaea'', the Mendocino cypress or pygmy cypress, is a taxon of disputed status in the genus ''Cupressus'' endemic to certain coastal terraces and coastal mountain ranges of Mendocino and Sonoma Counties in northwestern California. ...

'', ''

Cupressus lusitanica ''Cupressus lusitanica'', the Mexican cedar or cedar-of-Goa, is a species of cypress native to Mexico and Central America (Guatemala, El Salvador and Honduras). It has also been introduced to Belize, Costa Rica and Nicaragua, growing at altitu ...

'', ''

Platycladus orientalis ''Platycladus'' is a monotypic genus of evergreen coniferous trees in the cypress family Cupressaceae, containing only one species, ''Platycladus orientalis'', also known as Chinese thuja, Oriental arborvitae, Chinese arborvitae, biota or Orien ...

'', ''

Chamaecyparis lawsoniana ''Chamaecyparis lawsoniana'', known as Port Orford cedar or Lawson cypress, is a species of conifer in the genus ''Chamaecyparis'', family Cupressaceae. It is native to Oregon and northwestern California, and grows from sea level up to in the v ...

'', ''

Calocedrus decurrens ''Calocedrus decurrens'', with the common names incense cedar and California incense-cedar (syn. ''Libocedrus decurrens'' Torr.), is a species of coniferous tree native to western North America. It is the most widely known species in the genus, ...

'', ''

Juniperus chinensis ''Juniperus chinensis'', the Chinese juniper (圆柏, 桧) is a species of plant in the cypress family Cupressaceae, native to China, Myanmar, Japan, Korea and the Russian Far East. Growing tall, it is a very variable coniferous evergreen tree ...

'' and ''

Juniperus sabina ''Juniperus sabina'', the savin juniper or savin, is a species of juniper native to the mountains of central and southern Europe and western and central Asia, from Spain to eastern Siberia, typically growing at altitudes of .Farjon, A. (2005). ' ...

''. Even when a species is susceptible, environmental factors are important in the development of the disease. In California, for example, Monterey cypresses growing on the coastal ranges were found to be much less affected than those growing in inland areas where the climate was of a Mediterranean type.

Symptoms

The fungal spores gain entry into the tree through natural fissures or through injuries to the bark. The growth of the fungal

thalli Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms were ...

interferes with the

phloem Phloem (, ) is the living biological tissue, tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This tran ...

tissue of the

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

tree, cutting off the flow of sap and eventually killing the branch above the wound. The foliage turns yellow and the branch rapidly dies. A sunken

canker A plant canker is a small area of dead tissue, which grows slowly, often over years. Some cankers are of only minor consequence, but others are ultimately lethal and therefore can have major economic implications for agriculture and horticultur ...

with a reddish tinge develops at the original site of infection and

resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on natu ...

often oozes out nearby. Each canker is long and narrow and there may be several on one branch. Black circular sporing structures later appear alongside the canker.

Ecology

The disease can be spread between trees by rain splashes, small animals, birds or insects. The spores can gain entry through the stomata and lenticels under optimal conditions and

conidia A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non-motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to the ...

can get washed down branches by water trickles to lodge as new infective sites. The fungus can remain viable in dead tissue for several years. Vectors include bark beetles in the genus '' Phloeosinus'', and the cypress aphid (''Cinara cupressi'').

References

{{reflist Fungal plant pathogens and diseases Xylariales