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Gymnosporangium Spp. (Non-European)

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Gymnosporangium Spp. (Non-European) EuropeanBlackwell Publishing Ltd and Mediterranean Plant Protection Organization PM 7/73 (1) Organisation Européenne et Méditerranéenne pour la Protection des Plantes Diagnostics1 Diagnostic Gymnosporangium spp. (non-European) Specific scope Specific approval and amendment This standard describes a diagnostic protocol for Gymno- Approved in 2006-09. sporangium spp. Name: Gymnosporangium clavipes (Cooke & Peck) Cooke & Peck Introduction Synonyms: Gymnosporangium germinale F. Kern and The genus Gymnosporangium contains a number of species, Podisoma gymnosporangium-clavipes Cooke & Peck of which five are pests recommended for regulation in the Anamorph: Caeoma germinale Schwein. and Roestelia EPPO region (EPPO/CABI, 1997). The focus of this protocol aurantiaca Peck is the diagnosis of these five species: Gymnosporangium asiaticum, Taxonomic position: Fungi: Basidiomycetes: Uredinales G. clavipes, G. globosum, G. juniperi-virginianae and G. yamadae. EPPO computer code: GYMNCL The above mentioned Gymnosporangium species require Phytosanitary categorization: I/A1 – as Gymnosporangium two different host plants in order to complete their life cycles spp. (non-European). (heteroecious). The main hosts include apple (Malus pumila), pear (Pyrus spp.), quince (Cydonia oblonga), and other rosa- Name: Gymnosporangium globosum (Farl.) Farl. ceous species, depending upon the species of fungus involved. Synonyms: Gymnosporangium fuscum var. globosum Farl. On these hosts, aecia develop after dikaryotization of spermatia Anamorph: not known produced in spermogonia (pycnia). The aecia form aeciospores Taxonomic position: Fungi: Basidiomycetes: Uredinales infecting the alternate host juniper (Juniperus spp.). During the EPPO computer code: GYMNGL winter the fungus survives as mycelium on juniper, in spring on Phytosanitary categorization: I/A1 – as Gymnosporangium juniper telia with teliospores are formed. The basidiospores spp. (non-European). released by the germinated teliospores infect rosaceous species. Both the aeciospores and the basidiospores are airborne and can Name: Gymnosporangium juniperi-virginianae Schwein. be spread over large distances. Synonyms: Gymnosporangium macropus Link and Gymnosporangium virginianum Spreng. Anamorph: Aecidium pyrolatum Schwein. and Roestelia Identity pyrata Thaxt. Name: Gymnosporangium asiaticum Miyabe ex G. Yamada Taxonomic position: Fungi: Basidiomycetes: Uredinales Synonyms: Gymnosporangium haraeanum Syd. and P. Syd., EPPO computer code: GYMNJV Gymnosporangium chinense Long, Gymnosporangium koreaense Phytosanitary categorization: I/A1 – as Gymnosporangium H.S. Jacks. and Gymnosporangium spiniferum Syd. & P. Syd. spp. (non-European). Anamorph: Roestelia koreaensis P. Henn. Taxonomic position: Fungi: Basidiomycetes: Uredinales Name: Gymnosporangium yamadae Miyabe ex G. Yamada EPPO computer code: GYMNAS Synonyms: none Phytosanitary categorization: I/A1 – as Gymnosporangium Anamorph: not known spp. (non-European). Taxonomic position: Fungi: Basidiomycetes: Uredinales EPPO computer code: GYMNYA 1The figures in this standard marked ‘Web Fig.’ are published on the EPPO Phytosanitary categorization: I/A1 – as Gymnosporangium Website www.eppo.org. spp. (non-European). © 2006 OEPP/EPPO, Bulletin OEPP/EPPO Bulletin 36, 441–446 441 442 Diagnostics Detection Host plants of Gymnosporangium spp. G. asiaticum causes Japanese pear rust on Pyrus pyrifolia G. asiaticicum (Japanese pear), and may infect other Asian pear species, Pyrus Aecial hosts: Pyrus pyrifolia (Japanese pear), other Asian communis (European pear), Cydonia oblonga (quince) and pears, P. communis (European pear), Cydonia oblonga (quince), other rosaceous species on which pycnia and aecia are produced. Chaenomeles, Crataegus spp. (hawthorn) and Photinia. Aecia mature within a month after infection. In northern Japan, Telial hosts: Juniperus chinensis, J. procumbus (cedar). aeciospores infect the alternate hosts, Juniperus chinensis and J. procumbus in June and July causing swellings. The alternate G. clavipes hosts are not native to Europe, but widely grown as an ornamental Aecial hosts: Cydonia oblonga (quince), Malus pumila (apple), tree or kept as an indoor bonsai plant. On Juniper, telia are Amelanchier, Aronia, Chaenomeles, Crataegus spp. (hawthorn), produced in the following spring. The fungus may survive for Mespilus, Photinia, Cotoneaster, Sorbus and Pyrus communis many years in infected J. chinensis twigs, producing telia every (European pear). year. The fungus has been reported in Canada, the USA, China, Telial hosts: Juniperus virginiana, J. communis and J. communis Hong Kong, Japan, Korea, Russia (Far East) and Taiwan. alpine (syn. J. sibirica). G. clavipes causes Quince rust, also called Cedar-quince rust, which is an important disease of Malus pumila (apple) G. globosum in North America. The fungus infects fruit but not leaves of Aecial hosts: Crataegus spp. (hawthorn), Amelanchier, Malus, apple, and both leaves and fruit of Cydonia oblonga (quince), Pyrus, Sorbus. Crataegus spp. (hawthorn) and other rosaceous species. Telial hosts: Juniperus virginiana. It also infects pear, but does not cause a serious problem. In autumn, aeciospores infect young stems of Juniperus G. juniperi-viginianae communis and J. virginiana producing galls, from which telial Aecial hosts: Malus pumila (apple) and other Malus spp. horns emerge under wet conditions in the following spring. Telial hosts: Juniperus virginiana and other Juniperus spp. The galls are perennial and may produce telia for 20 years. The fungus has been reported in Canada, Mexico, the USA G. yamadae and Guatemala. Aecial hosts: Malus pumila (apple) and other Malus spp. G. globosum causes American hawthorn rust, also called Telial hosts: Juniperus chinensis. Cedar hawthorn rust, and infects leaves of Crataegus spp. (hawthorn), but also leaves of Malus pumila (apple), Pyrus Symptoms caused by different Gymnosporangium spp. spp. (pear) and other rosaceous species in eastern North on different hosts America. It rarely infects fruits and is a minor disease compared with cedar apple rust (see below) and quince rust. However, Pyrus spp. G. globosum can cause severe infections on Crataegus seed- Pyrus pyrifolia. lings in nurseries. Its alternate host is Juniperus virginiana, G. asiaticum produces pycnia on the upper surface of the leaves which is an important timber and amenity tree in North America. and aecia on the lower surface on thickened brown spots in a Infection on J. virginiana causes galls. After germination of dense group or ring opposite the pycnia (Web Fig. 1a). The aecia aeciospores and subsequent infection, an overwintering latent are white, long and tubular, becoming ruptured at the tip, about mycelium is produced on J. virginiana which can stay viable for 3–6 × 0.25 mm with rusty-brown contents. more than one year. In spring, the telia produce basidiospores which infect rosaceous hosts again. The fungus has been reported Malus spp. in Canada, Mexico and the USA. G. juniperi-virginianae causes Cedar apple rust on Malus Malus pumila. pumila (apple) and other Malus spp. Apple is an important crop G. clavipes infects fruits, but not leaves of apple. Pycnia and in the EPPO region. On apple, aecia and pycnia are produced on aecia are rarely developed on apple fruits and clear rust the leaves. The galls on the alternate host J. virginiana are symptoms are often absent. On fruit, a dark green lesion occurs annual, producing only one batch of telia. The fungus has been at the calyx end, causing distortion of the fruit. G. clavipes reported in Canada and the USA. causes lesions on fruit which extends to the core, while G. G. yamadae causes Japanese apple rust. It occurs in most juniperi-virginianae causes only superficial lesions on fruit apple-growing regions of Japan and causes damage by defoliation. (Web Fig. 2a). Its morphology and disease cycle most closely resemble those G. juniperi-virginianae produces aecia and pycnia on the of G. globosum. Pycnial and aecial lesions on apple leaves leaves. Small yellow-orange lesions appear on the upper surface resemble those of cedar apple rust. Fruit infections are rare. The of the leaves and petioles, in which the pycnia are formed alternate host is Juniperus chinensis. The galls on J. chinensis in small groups of 1–3 mm diameter. Several weeks later, produce telia for a period of one year only. The pathogen has yellow-brown lesions appear on the undersurface, in which the been reported in Japan, Korea and China. aecia are formed. In this stage, leaves may show cupping and © 2006 OEPP/EPPO, Bulletin OEPP/EPPO Bulletin 36, 441–446 Gymnosporangium spp. 443 curling. On susceptible cultivars, infection of G. juniperi- Identification virginianae can result in defoliation. Sometimes, superficial brown necrotic lesions on apple fruits can be observed. Some- Identification of the Gymnosporangium species mentioned is times these lesions contains pycnia, but rarely aecia (Web based on host-pathogen relations and morphological characters Fig. 4a,b,c). on plant material. Gymnosporangium species are obligate and G. yamadae produces aecia and pycnia on the leaves. cannot be cultured on artificial media. So far, no information on Pycnia occur on the upper side in small groups. Aecia, 3–8 mm molecular diagnosis has been reported. high × 0.3–0.5 mm diameter, occur on the lower surface of Usually, identification can only be done on aeciospores pro- leaves (Web Fig. 5a). On susceptible cultivars, G. yamadae can duced on the rosaceous species. The morphology of teliospores
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