| Picture | Title | Caption | Copyright |
|---|---|---|---|
| Telia | Telia of Puccinia buxi on Buxus spp. Original x5. | USDA-ARS/Systematic Mycology & Microbiology Laboratory | |
| Teliospores | Teliospores of Puccinia buxi on Buxus spp. Original x400. Note scale bar. | USDA-ARS/Systematic Mycology & Microbiology Laboratory | |
| Teliospore | Teliospore of Puccinia buxi on Buxus spp. Original x400. Note scale bar. | USDA-ARS/Systematic Mycology & Microbiology Laboratory | |
| Teliospores | Teliospores of Puccinia buxi on Buxus spp. Original x400. Note scale bar. | USDA-ARS/Systematic Mycology & Microbiology Laboratory |
Datasheet
Puccinia buxi
Index
- Pictures
- Identity
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Description
- Distribution
- Distribution Table
- History of Introduction and Spread
- Introductions
- Risk of Introduction
- Habitat List
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- Symptoms
- List of Symptoms/Signs
- Biology and Ecology
- Climate
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Plant Trade
- Impact Summary
- Economic Impact
- Environmental Impact
- Social Impact
- Risk and Impact Factors
- Diagnosis
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- References
- Contributors
- Distribution Maps
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Top of pageIdentity
Top of pagePreferred Scientific Name
- Puccinia buxi Sowerby 1809
Other Scientific Names
- Dasyspora buxi Arthur 1906
- Dicaeoma buxi (Sowerby) Gray 1821
- Micropuccinia buxi (Arthur) Arthur & H.S. Jacks. 1921
- Puccinia buxi DC. 1815
- Trailia buxi (Arthur) Syd. 1922
International Common Names
- English: Boxwood rust
Summary of Invasiveness
Top of pageP. buxi is an autoecious microcyclic rust, completing its life cycle with two spore forms on one host. It is native to parts of Europe and Asia. An introduction to the USA, is evidence that it can be invasive with respect to other temperate countries, particularly because its hosts in the genus Buxus are often propagated vegetatively and may carry latent infections. Boxwoods have long been popular as ornamentals, therefore the rust’s current absence from North America and temperate regions of the southern hemisphere is puzzling; in the earliest introductions of the host, the pathogen would probably have been ignored or overlooked. Conditions of boxwood cultivation may discourage the rust’s growth and survival.
Taxonomic Tree
Top of page- Domain: Eukaryota
- Kingdom: Fungi
- Phylum: Basidiomycota
- Subphylum: Pucciniomycotina
- Class: Pucciniomycetes
- Order: Pucciniales
- Family: Pucciniaceae
- Genus: Puccinia
- Species: Puccinia buxi
Notes on Taxonomy and Nomenclature
Top of pageThis species is frequently cited as Puccinia buxi DC., but DeCandolle’s name is an illegitimate homonym of Sowerby’s binomial; Arthur’s binomial is treated as a new name (nomen novum).
Description
Top of pageSpermogonia, aecia and uredinia absent. Telia amphigenous, on indefinite spots, scattered or confluent, hemispherical, pulvinate, compact, erumpent, dark chestnut-brown. Teliospores oblong to clavate, rounded above, apex not thickened, rounded or attenuate below, 55-90 x 20-35 µm, up to 100 µm long, walls 2.0-2.5 µm thick, brown, upper cell with apical germ pore, lower cell with superior germ pore; pedicels hyaline, persistent, very long, up to 160 µm.
See Grove (1913) and Hiratsuka et al. (1992) for more details.
Distribution
Top of pageP. buxi has been reported from Europe, North Africa, Iran, Japan, and China (Dennis, 1986). Occurrence in the islands of the Azores, Madeira, and the Ryukyus of Japan (Dennis, 1986) are presumably the result of introductions. Specimens have been collected from other parts of the range of the primary host, Buxus sempervirens (boxwood) (BPI, 2009).
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.
Last updated: 17 Feb 2021| Continent/Country/Region | Distribution | Last Reported | Origin | First Reported | Invasive | Reference | Notes |
|---|---|---|---|---|---|---|---|
Asia |
|||||||
| China | Present | ||||||
| -Sichuan | Present, Localized | Daba Mountains | |||||
| Iran | Present | ||||||
| Japan | Present | Present based on regional distribution. | |||||
| -Kyushu | Present, Few occurrences | ||||||
| -Ryukyu Islands | Present | ||||||
| Turkey | Present | ||||||
Europe |
|||||||
| Belgium | Present | 1883 | |||||
| Croatia | Present | ||||||
| France | Present, Widespread | Native | |||||
| Germany | Present | ||||||
| Greece | Present | Native | |||||
| Ireland | Present | 1933 | |||||
| Italy | Present | 1876, 1882, 1889 | |||||
| Poland | Present | ||||||
| Portugal | Present | ||||||
| -Azores | Present | ||||||
| -Madeira | Present, Few occurrences | ||||||
| Russia | Present | Present based on regional distribution. | |||||
| -Southern Russia | Present | Near Chosta in Caucasus Moutains. 1982 | |||||
| Slovenia | Present | In arboretum | |||||
| Spain | Present | Native | Original citation: Llorens i Villagrassa I (1984) | ||||
| Switzerland | Present | 1850, 1900, 1927 | |||||
| United Kingdom | Present, Widespread | ||||||
North America |
|||||||
| United States | Present | Present based on regional distribution. | |||||
| -Georgia | Present | 2004 | |||||
| -Maryland | Present | ||||||
| -Pennsylvania | Absent, Eradicated | 2006 | One location | ||||
History of Introduction and Spread
Top of pageIn the summer of 2005, a nursery in Pennsylvania, USA received a shipment of boxwood (Buxus sempervirens) cuttings from various locations in Greece (NAPPO, 2006). Rooted cuttings were found to be infected with P. buxi the next spring. The infected plants were destroyed by autoclaving, and another shipment to an American nursery was quarantined.
Introductions
Top of page| Introduced to | Introduced from | Year | Reason | Introduced by | Established in wild through | References | Notes | |
|---|---|---|---|---|---|---|---|---|
| Natural reproduction | Continuous restocking | |||||||
| Maryland | Greece | 2005 | Horticulture (pathway cause) | NAPPO (2006) | Accidental, eradicated | |||
Risk of Introduction
Top of pageAs the infection can be asymptomatic during the usual growing season, infected plant material or plants can be collected or grown and then transported across borders and oceans. Obviously infected material coming from various European countries to the USA also has been intercepted by the phytosanitary authorities (BPI, 2009). Boxwood (Buxus sempervirens) has long been a popular ornamental plant, thus it is surprising that introduction in earlier times has not resulted in establishment of this pathogen in the USA and other countries in temperate regions outside Europe. The usual conditions of boxwood cultivation and care may prevent the rust from surviving and proliferating (Durrieu, 2001), but the biology of the fungus is not known well enough to explain its low rate of spread.
Habitat List
Top of page| Category | Sub-Category | Habitat | Presence | Status |
|---|---|---|---|---|
| Terrestrial | Managed | Managed forests, plantations and orchards | Present, no further details | Natural |
| Terrestrial | Natural / Semi-natural | Natural forests | Present, no further details | Natural |
Hosts/Species Affected
Top of pageThe rust has been reported from Buxus sempervirens (boxwood) and Buxus microphylla (littleleaf boxwood), commonly grown ornamentals, as well as from the Asian species, Buxus sinica (Chinese boxwood), a cold-hardy species from Korea (Batdorf, 1995).
Host Plants and Other Plants Affected
Top of page| Plant name | Family | Context | References |
|---|---|---|---|
| Buxus balearica | Buxaceae | Other | |
| Buxus microphylla (little-leaf box) | Buxaceae | Other | |
| Buxus microphylla var. japonica | Buxaceae | Other | |
| Buxus rugulosa | Buxaceae | Unknown | Zhang et al. (1997) |
| Buxus sempervirens (common boxwood) | Buxaceae | Main | Baur et al. (2019); Camacho et al. (2018); Cech et al. (2010); Gjaerum (1982); Hauptman (2008); Tavares et al. (2014); Lehtıjärvı et al. (2014); Cech et al. (2010) |
| Buxus sinica (chinese box) | Buxaceae | Other |
Symptoms
Top of pageBlack telia develop on indefinite spots on thickened areas of the leaves (Grove, 1913). Smith et al. (1988) report hypertrophy and dieback of new growth caused by this rust.
List of Symptoms/Signs
Top of page| Sign | Life Stages | Type |
|---|---|---|
| Leaves / abnormal colours | ||
| Leaves / abnormal leaf fall | ||
| Leaves / fungal growth | ||
| Leaves / leaves rolled or folded | ||
| Stems / dieback |
Biology and Ecology
Top of pageP. buxi is an autoecious microcyclic rust, completing its life cycle on one host. Teliospores develop in the leaves through autumn and winter, emerging through the epidermis in winter or spring. They are not shed, but remain on the leaf and germinate without dormancy (Wilson and Henderson, 1966). The basidiospores produced then infect the new leaves (Grove, 1913). The teliospores have been reported to fall apart easily into their two cells (Grove, 1913), but the possible role of this character in dissemination of the fungus has not been examined.
Preece (2000) reported that the rust is relatively rare in Great Britain, occurring only on old bushes/trees, some hundreds of years old, but the many newer plantings or plants for sale in recent decades have not been infected. When Preece did find rusted leafy material, it had been imported from southern Europe. In response to Preece’s presentation, Durrieu (2001) reported that the rust, though common on wild boxwood in Europe, is absent in areas of the Pyrenees mountains and in Spain where the host grows without tree cover. On the other hand, the rust is prevalent in shady places regardless of plant age; fir [Abies] or beech [Fagus/Nothofagus] forests on northern slopes usually harbour infected boxwood plants. According to Durrieu, the rust appears only on north sides of shaded bushes, not on the sunny sides. Thus the fungus appears to require the shaded, more humid conditions natural to the understory habitat of the wild boxwood (Batdorf, 1995). As in Great Britain, rust is absent from the smaller plants cultivated in French gardens, but is found on larger plants in old gardens where the plants are shaded (Durrieu, 2001). Durrieu further noted that the rust infects only new growth, not older leaves, and suggests that regular pruning of garden plants, removing the newer growth, may restrict the survival and spread of boxwood rust.
Climate
Top of page| Climate | Status | Description | Remark |
|---|---|---|---|
| Cf - Warm temperate climate, wet all year | Preferred | Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year | |
| Cs - Warm temperate climate with dry summer | Preferred | Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers |
Means of Movement and Dispersal
Top of pageNatural Dispersal (Non-Biotic)
Rust basidiospores are usually wind-disseminated (Alexopoulos et al., 1996). The teliospores are reported to break apart (Grove, 1913); this may be a mechanism for dispersal of the upper cells.
Accidental Introduction
In the summer of 2005, a nursery in Pennsylvania, USA received a shipment of boxwood (Buxus sempervirens) cuttings from various locations in Greece (NAPPO, 2006). Rooted cuttings in the nursery then developed telia of P. buxi in spring 2006.
Preece (2000) observed telia of the rust in England on cuttings in floral bouquets imported from southern Europe.
Pathway Causes
Top of page| Cause | Notes | Long Distance | Local | References |
|---|---|---|---|---|
| Cut flower trade | Foliage used as greenery in bouquets | Yes | Yes | Preece (2000) |
| Horticulture | Yes | Yes | NAPPO (2006) | |
| Nursery trade | Anticipated possibility | Yes | Yes | NAPPO (2006) |
Pathway Vectors
Top of page| Vector | Notes | Long Distance | Local | References |
|---|---|---|---|---|
| Plants or parts of plants | latent or overlooked infections | Yes | Yes | NAPPO (2006); Preece (2000) |
| Wind | Basidiospores | Yes | Alexopoulos et al. (1996) |
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 | fungi/hyphae; fungi/spores | 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 |
| Stems (above ground)/Shoots/Trunks/Branches |
| True seeds (inc. grain) |
| Wood |
Economic Impact
Top of pageAny losses due to this fungus are likely to result from restriction on exports or imports of Buxus plants or plant material, or from the destruction of infected imported planting material by nurseries or quarantine authorities.
Environmental Impact
Top of pageSome Buxus species are endangered or threatened (Batdorf, 2004); introduction of the rust to their native regions could add to the threats to their survival.
Social Impact
Top of pageThe presence of the pathogen in Europe has not prevented use as an ornamental in new plantings (Preece, 2000; Durrieu, 2001).
Risk and Impact Factors
Top of page
Invasiveness
- Proved invasive outside its native range
- Has a broad native range
- Abundant in its native range
- Tolerant of shade
- Host damage
- Parasitism (incl. parasitoid)
- Pathogenic
- Highly likely to be transported internationally accidentally
- Difficult to identify/detect as a commodity contaminant
Diagnosis
Top of pageNo DNA sequences of this species that could be used in laboratory identification of the fungus or detection of the fungus in plant tissue have been deposited in the GenBank database (NCBI, 2009) as of September, 2009.
Detection and Inspection
Top of pageBoth sides of the newest leaves of Buxus plants should be inspected for black pustules containing large, thick-walled, two-celled stalked spores. On plants without pustules, the newest leaves should be examined for spots accompanied by a thickening of the leaves.
Similarities to Other Species/Conditions
Top of pageNo other rust fungi are reported on Buxus species. The asexual fungus Macrophoma candollei [Dothiorella candollei] also causes leaf spots on boxwood (Buxus sempervirens). Its small black pycnidia develop on the undersides of leaves, but the disease begins and is more severe on the oldest of the bush’s foliage, rather than on the newest leaves. The pycnidia produce tendrils, often called cirrhi, of single-celled spores (Batdorf, 1995).
Prevention and Control
Top of pageDue to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
SPS Measures
The Animal and Plant Health Inspection Service of the US Department of Agriculture (APHIS-USDA) developed rules for permitting the importation of artificially dwarfed or “penjing” plants from China, in pots containing growth media rather than bare-rooted (USDA/APHIS, 2003). Buxus sinica (Chinese boxwood), a host for P. buxi (Zhang et al., 1997), was among the plants governed by the rule. Requirements for production of plants for export that relate to the exclusion of P. buxi include that the plants should be developed from clean inspected “mother” stock, that they should be rooted and grown in approved media in an active condition for at least 4 months before export, and during that time, they are kept in a greenhouse practicing sanitary procedures, including inspections, to exclude pests and pathogens (USDA/APHIS, 2003).
After this rust was reported from a nursery in Pennsylvania, USA, a quarantine was placed on rooted cuttings and plants resulting from a shipment of Buxus material from Greece to a nursery in Maryland in the USA (NAPPO, 2006).
Fungicide sprays should be prohibited during such post-entry quarantine of Buxus plants because the fungicides can suppress development of the fungus and disease symptoms. The distribution or sale of asymptomatic plants could spread the fungus to other areas (NAPPO, 2006).
Cultural Control and Sanitary Measures
Planting for sun and air circulation, as well as thinning and pruning for control of other fungal diseases (Batdorf, 1995), may create conditions that retard the growth and spread of P. buxi. The removal of any shed leaves will reduce available inoculum. As Durrieu (2001) indicates, pruning may remove susceptible and/or infected leaves.
Gaps in Knowledge/Research Needs
Top of pageMore information is needed on the biology and ecology of this rust fungus, including the means and conditions of dispersal and the conditions of temperature and humidity required for germination, infection, growth and sporulation.
References
Top of pageDennis RWG, 1986. Fungi of the Hebrides. Kew, UK: Royal Botanic Gardens, 383 pp.
Dennis RWG, 1995. Fungi of South East England. Richmond, UK: Royal Botanic Gardens, 295 pp.
Durrieu G, 2001. More about box rust (Puccinia buxi). Mycologist, 15:144.
Gjaerum, H. B., 1982. Rust fungi from Madeira. In: Boletim do Museu Municipal do Funchal,34. 5-22.
Distribution References
Bensaude Mathilde, 1926. Kew Bulletin of Miscellaneous Information, 381-389.
BPI (US National Fungus Collections), 2009. Fungal Databases - Specimens., Beltsville, USA: Systematic Mycology and Microbiology Laboratory, Agricultural Research Service, USDA. http://www.nt.ars-grin.gov/fungaldatabases/specimens/specimens.cfm
CABI, Undated. Compendium record. Wallingford, UK: CABI
CABI, Undated a. CABI Compendium: Status inferred from regional distribution. Wallingford, UK: CABI
CABI, Undated b. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
Dennis R W G, 1986. Fungi of the Hebrides. Kew, UK: Royal Botanic Gardens. 383 pp.
Durrieu G, 2001. More about box rust (Puccinia buxi). Mycologist. 144.
Gjaerum H B, 1982. Rust fungi from Madeira. In: Boletim do Museu Municipal do Funchal. 34 5-22.
Contributors
Top of page10/09/09 Original text by:
Systematic Mycology & Microbiology Laboratory, USDA-ARS, 10300 Baltimore Ave., Beltsville, MD 20705, USA
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