Datasheet
Discula destructiva (anthracnose of dogwood)
Index
- Pictures
- Identity
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Description
- Distribution
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- Symptoms
- List of Symptoms/Signs
- Biology and Ecology
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Plant Trade
- Wood Packaging
- Impact Summary
- Impact
- Environmental Impact
- Impact: Biodiversity
- Social Impact
- Similarities to Other Species/Conditions
- Prevention and Control
- References
- Distribution Maps
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Top of page| Picture | Title | Caption | Copyright |
|---|---|---|---|
| Foliar symptoms | Discula destructiva (Dogwood anthracnose); foliar symptoms of dogwood anthracnose on flowering dogwood (Cornus florida L.) | ©John Hartman/University of Kentucky/Bugwood.org - CC BY-NC 3.0 US | |
| Floral symptoms | Discula destructiva (Dogwood anthracnose); floral symptoms of dogwood anthracnose on flowering dogwood (Cornus florida L.) | ©Robert L. Anderson/USDA Forest Service/Bugwood.org - CC BY 3.0 US |
Identity
Top of pagePreferred Scientific Name
- Discula destructiva Redlin 1991
Preferred Common Name
- anthracnose of dogwood
EPPO code
- DISCDE (Discula destructiva)
Summary of Invasiveness
Top of page Since there is a very strong presumption that D. destructiva is alien to North America (Trigiano et al. 1995), this pathogen is clearly very invasive in US deciduous forests, seriously modifying their understorey composition and biodiversity by destroying species of Cornus which form a characteristic element of this ecosystem.Taxonomic Tree
Top of page- Domain: Eukaryota
- Kingdom: Fungi
- Phylum: Ascomycota
- Subphylum: Pezizomycotina
- Class: Sordariomycetes
- Subclass: Sordariomycetidae
- Order: Diaporthales
- Family: Valsaceae
- Genus: Discula
- Species: Discula destructiva
Notes on Taxonomy and Nomenclature
Top of page No teleomorph is known, but other species of Discula have teleomorphs in the genera Apiognomonia and Gnomoniella. Zhang and Blackwell (2001) confirm from DNA sequence analyses that D. destructive has clear affinity with Diaporthales.Description
Top of page Conidia are of the typical anthracnose type, 7-12 x 2.5-5.5 µm, hyaline, non-septate, smooth, with a truncate base and often polar guttules (Redlin, 1991; Daughtrey et al., 1996). In mass, they form a slimy, white to beige or pinkish ooze. The conidioma (acervuli) form in leaf or twig tissues, erupting through the surface often around a trichome, typically 30-135 µm diameter and rounded on the underside of leaves, or 90-340 µm long and slightly elongated on twigs. They appear dark in the tissues of overwintered twigs. The teleomorph has not been reported.Distribution
Top of page D. destructiva was detected in 1995 in the UK on imported Cornus florida from the USA.Distribution Table
Top of pageThe distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
| Continent/Country/Region | Distribution | Last Reported | Origin | First Reported | Invasive | Reference | Notes | |
|---|---|---|---|---|---|---|---|---|
North America | ||||||||
| Canada | Restricted distribution | CABI/EPPO, 2004; EPPO, 2014 | ||||||
| -British Columbia | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Ontario | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| USA | Widespread | CABI/EPPO, 2004; EPPO, 2014 | ||||||
| -Alabama | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -California | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Connecticut | Restricted distribution | Introduced | 1983 | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | ||||
| -Delaware | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -District of Columbia | Restricted distribution | CABI/EPPO, 2004; EPPO, 2014 | ||||||
| -Georgia | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Idaho | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Illinois | Restricted distribution | Introduced | 1995 | Schwegman et al., 1998; CABI/EPPO, 2004; EPPO, 2014 | ||||
| -Indiana | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Kansas | Restricted distribution | Introduced | 1994 | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | ||||
| -Kentucky | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Maryland | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Massachusetts | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Michigan | Restricted distribution | Introduced | 1993 | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | ||||
| -Mississippi | Restricted distribution | Introduced | 1994 | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | ||||
| -Missouri | Restricted distribution | CABI/EPPO, 2004; EPPO, 2014 | ||||||
| -New Hampshire | Restricted distribution | Introduced | 1991 | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | ||||
| -New Jersey | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -New York | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -North Carolina | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Ohio | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Oregon | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Pennsylvania | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Rhode Island | Restricted distribution | Introduced | 1992 | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | ||||
| -South Carolina | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Tennessee | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -Vermont | Restricted distribution | CABI/EPPO, 2004; EPPO, 2014 | ||||||
| -Virginia | Restricted distribution | Introduced | 1987 | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | ||||
| -Washington | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
| -West Virginia | Restricted distribution | Introduced | Daughtrey et al., 1996; CABI/EPPO, 2004; EPPO, 2014 | |||||
Europe | ||||||||
| Germany | Present, few occurrences | Introduced | Stinzing and Lang, 2003; CABI/EPPO, 2004; EPPO, 2014 | |||||
| Italy | Restricted distribution | CABI/EPPO, 2004; EPPO, 2014 | ||||||
| Netherlands | Absent, confirmed by survey | EPPO, 2014 | ||||||
| Switzerland | Restricted distribution | EPPO, 2014 | ||||||
| UK | Absent, intercepted only | CABI/EPPO, 2004; EPPO, 2014 | ||||||
History of Introduction and Spread
Top of page Dogwood anthracnose was first reported in the USA in 1978 on flowering dogwoods (Cornus florida) in north-eastern states (New York and Connecticut). It was later realized that similar symptoms had also been observed on C. nuttallii on the west coast in 1976. In both cases, the causal agent was identified as D. destructiva in 1991. The disease then spread rapidly and caused serious losses. Genetic studies have revealed a lack of diversity among isolates from the two coasts. Considering the rapid spread around points of entry (New York and Seattle) and the severity of the disease, it is supposed that D. destructiva is an introduced pathogen.Risk of Introduction
Top of page In the USA, the further spread of D. destructiva poses a strong phytosanitary risk for native Cornus spp. grown both as ornamentals and occurring naturally in forests. Particularly in the eastern states, dogwoods have a strong emblematic value. A 10-point control programme has been developed with the support of a Dogwood Anthracnose Work Group, involving researchers, foresters, nurserymen and regulatory personnel (Daughtrey et al., 1996). Limiting interstate movement of infected host material is recommended. Though there is a general tendency for disease severity to decrease, it remains high at the southern edge where the disease is still spreading. In principle, there is also a risk for other continents where Cornus spp. occur or are grown as ornamentals, particularly Europe. The main hosts Cornus florida and C. nuttallii are not native, but are valuable amenity plants for parks and gardens. Of the two native species, Cornus mas has been found to be resistant, while the susceptibility of the much more abundant C. sanguinea is not known. However, neither wild nor cultivated species in Europe have the particular importance of the dogwoods in North America. Other species of Cornus occur through the remainder of the Palaearctic region. If only by default (as the disease was not previously known in either North America or Europe), it seems possible that D. destructiva originates in Asia, on native species whose resistance has made it inconspicuous.Hosts/Species Affected
Top of page The North American species Cornus florida (flowering dogwood) and C. nuttallii (Pacific dogwood) are particularly susceptible. Cornus kousa, C. alternifolia and C. amomum are reported as relatively resistant (Sherald et al., 1994). The European Cornus mas is considered resistant in North America (Stinzing and Lam, 2003), but there is no information for C. sanguinea. Nothing appears to be reported concerning Asian species of Cornus.Host Plants and Other Plants Affected
Top of page| Plant name | Family | Context |
|---|---|---|
| Cornus alba (red-barked dogwood) | Cornaceae | Other |
| Cornus controversa (giant dogwood) | Cornaceae | Other |
| Cornus florida (Flowering dogwood) | Cornaceae | Main |
| Cornus nuttallii (Pacific dogwood) | Cornaceae | Main |
| Cornus sericea (redosier dogwood) | Cornaceae | Other |
| Cornus stolonifera | Cornaceae | Other |
Growth Stages
Top of page Flowering stage, Seedling stage, Vegetative growing stageSymptoms
Top of page Initial symptoms are small leaf spots with a purple margin, which then develop into large necrotic blotches. In many cases, infected mature leaves die prematurely. Sometimes, they remain attached to the stems after normal leaf fall. Infection expands from leaves to small twigs and then branches. Twig and branch dieback start in the lower crown (hence the original name of the disease 'lower branch dieback'). Numerous epicormic shoots often form at the base of the trunk or on branches. D. destructiva causes cankers which can kill the tree. The fungus can kill trees of all sizes, but is more severe on young seedlings and understorey forest dogwoods.List of Symptoms/Signs
Top of page| Sign | Life Stages | Type |
|---|---|---|
| Leaves / abnormal colours | ||
| Leaves / necrotic areas | ||
| Leaves / yellowed or dead | ||
| Stems / canker on woody stem | ||
| Stems / dieback | ||
| Stems / witches broom | ||
| Whole plant / plant dead; dieback |
Biology and Ecology
Top of page D. destructiva persists as cankers on the trunks and branches of its hosts, or in twigs or dead leaves carrying conidiomata. Conidia formed in conidiomata (acervuli) on cankers are rain-splashed to newly expanded leaves in spring, which they infect under humid conditions. Lesions on the leaves may remain as small spots, form larger blotches, or blight the whole leaf, spreading into the petiole and infecting the shoot. At flowering, bracts are also infected. Conidia may infect the current season's shoots directly, forming small cankers which are usually rapidly delimited by callus tissue. However, shoots infected from blighted leaves become more severely cankered and die back. This shoot dieback often results in the development of epicormic shoots on the branches and trunk, which become infected in turn. Heavily infected young trees may be killed but, if conditions become less favourable for disease development in subsequent seasons, branch and trunk cankers may be contained and the tree recovers.In culture, optimal growth is at 21-24°C, no growth occurs at 27°C. Infection is favoured by cool, wet spring and autumn, but can occur throughout the growing season. Low light intensity and drought stress are predisposing factors (Erbaugh et al., 1995).
See Daughtrey and Hibben (1994) and Daughtrey et al. (1996).
Notes on Natural Enemies
Top of page dsRNA has been detected in isolates of D. destructiva (i.e. a fungal virus; Yao and Tainter, 1996). There is a possibility that this could be associated with a decrease in virulence. By analogy with the control of chestnut blight (Endothia parasitica [Cryphonectria parasitica]), it is conceivable that hypovirulent strains could be used in disease control.Means of Movement and Dispersal
Top of page Short distance dispersal of conidia probably occurs via rainsplash. Field dispersal by coccinellids (Hippodamia convergens) has been observed. Birds and other animals (Holt et al., 1998) may possibly carry the pathogen, even in fruits or seeds, which have been shown to contain the pathogen (Britton et al., 1993). Trade of infected plants ensures long distance dispersal.Plant Trade
Top of page| Plant parts liable to carry the pest in trade/transport | Pest stages | Borne internally | Borne externally | Visibility of pest or symptoms |
|---|---|---|---|---|
| Leaves | hyphae; spores | Yes | Pest or symptoms not visible to the naked eye but usually visible under light microscope | |
| Stems (above ground)/Shoots/Trunks/Branches | hyphae; spores | Yes | Pest or symptoms not visible to the naked eye but usually visible under light microscope |
| Plant parts not known to carry the pest in trade/transport |
|---|
| Bark |
| Bulbs/Tubers/Corms/Rhizomes |
| Flowers/Inflorescences/Cones/Calyx |
| Fruits (inc. pods) |
| Growing medium accompanying plants |
| Roots |
| Seedlings/Micropropagated plants |
| True seeds (inc. grain) |
| Wood |
Wood Packaging
Top of page| Wood Packaging not known to carry the pest in trade/transport |
|---|
| Loose wood packing material |
| Non-wood |
| Processed or treated wood |
| Solid wood packing material with bark |
| Solid wood packing material without bark |
Impact Summary
Top of page| Category | Impact |
|---|---|
| Animal/plant collections | None |
| Animal/plant products | None |
| Biodiversity (generally) | Negative |
| Crop production | None |
| Environment (generally) | Negative |
| Fisheries / aquaculture | None |
| Forestry production | None |
| Human health | None |
| Livestock production | None |
| Native fauna | Negative |
| Native flora | Negative |
| Rare/protected species | None |
| Tourism | None |
| Trade/international relations | None |
| Transport/travel | None |
Impact
Top of page In the USA, in addition to the environmental impacts, consecutive years of infection have killed many ornamental Cornus spp. in parks and gardens. The disease now presents a considerable problem for nursery production of healthy plants.Environmental Impact
Top of page In the USA, a significant proportion of woodland dogwood populations has been killed. In 1984, a survey in a national park in Maryland showed, in a severe case, that only 3% of dogwoods were free from anthracnose and 33% were dead. In 1988, 89% trees were dead and all remaining trees were infected. In the short term, at least, the disease is causing a clear change in forest understorey composition in eastern forests (Jenkins and White, 2002), with a substantial effect on their amenity value for the public. Nevertheless, the impact of the disease varies with site and past history (Chellemi et al., 1992; McEwan et al., 2000), so dogwoods are not seriously endangered. Indeed, the importance of the disease appears to be declining in areas where it was first introduced.Impact: Biodiversity
Top of page D. destructiva is clearly very invasive in deciduous forests in the USA, seriously modifying their understorey composition and biodiversity by destroying species of Cornus, which form a characteristic element of this ecosystem. It may secondarily affect other forest plants and animals by modifying the canopy structure and the availability of dogwood leaves and fruits as food (Rossell et al., 2001).Social Impact
Top of page Dogwoods are emblematic plants in the eastern USA, in nature and in gardens (for example, dogwood is the state flower of North Carolina). Their decline has a clear aesthetic impact.Similarities to Other Species/Conditions
Top of page D. destructiva was initially confused with the anamorph of Glomerella cingulata, already well known on this host. Various other fungi cause leaf spots of Cornus (Elsinoë corni, species of Septoria, Ascochyta cornicola, Botryotinia fuckeliana), but these are easily distinguished microscopically.Prevention and Control
Top of page Control of the disease is difficult, particularly in forests. In parks and gardens, cultural control (adequate watering and fertilization, pruning, removal of fallen leaves) and chemical control can be used. In the USA, emphasis is given to: optimum fertilization, trickle irrigation, adequate sunlight, mulching, pruning, fungicides, resistant cultivars, limiting movement of nursery material (Daughtrey et al., 1996). Forest management techniques favourable to the survival of understorey dogwoods remain to be worked out, but Britton et al. (1994) suggest that anthracnose is less severe on stands which were clear-cut 30 years ago than on those where timber was only partially harvested.Phytosanitary measures
No international measures are currently applied for D. destructiva. As the main risk of introduction is by movement of infected plants for planting, it would be appropriate to require such material to come from a pest-free area or pest-free place of production.
References
Top of pageEPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Yao JM; Tainter H, 1996. Virus-like particles from Discula destructiva. Canadian Journal of Plant Pathology, 18: 433-438.
Zhang N; Blackwell, 2001. Molecular phylogeny of dogwood anthracnose fungus (Discula destructiva) and the Diaporthales. Mycologia, 93: 355-365.
Distribution Maps
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