DOCSLIB.ORG

27. Poplar Leaf Rusts Michael E

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
27. Poplar Leaf Rusts Michael E Hardwood Diseases 27. Poplar Leaf Rusts Michael E. Ostry and Jennifer Juzwik Hosts All Populus species are potential hosts of poplar leaf rust fungi, Melamp­ sora species. Distinguishing different leaf rust species is often problematic. Com­ plexity in leaf rust situations is related to the extensive planting of many poplar species and interspecific hybrids, natural or human­aided movement of Melampsora species into new geographic regions, and the occurrence of Melampsora races (formae speciales). Furthermore, mixed race infections on single leaves and the evolution of natural hybrids of rust fungi contribute to this complexity. A critical need exists for monitoring poplar rust Figure 27.1—Uredinia pustules with urediniospores of Melampsora medusae on poplar leaf. Photo by Michael E. populations in this intricate system. Two Ostry, USDA Forest Service. poplar leaf rusts are dominant in the United States. In the East, larch is the alternate host of M. medusae; in the West, Douglas­ fir is the alternate host for M. occidentalis. Infection of coniferous alternate hosts is confined to young needles and the damage is usually minor. Distribution Melampsora leaf rusts affect native and introduced hybrid poplars throughout North America. Damage Leaf rust can cause partial or com­ plete defoliation by midsummer, reducing Figure 27.2—Uredinia pustules with urediniospores of Melampsora occidentalis on poplar leaf. Photo by seedling vigor and quality. Premature Michael E. Ostry, USDA Forest Service. defoliation can predispose seedlings to environmental stresses and invasion by secondary damaging agents. rupture, large numbers of powdery and release powdery aeciospores. Aecia urediniospores are released. From late are preceded by an inconspicuous stage Diagnosis summer to autumn, yellowish crusts (pycnia) that produce their pycniospores (telia), darkening to brown, are produced in droplets (fig. 27.3). The uredinio­ On poplar leaves, look for orange­ among the uredinia. On conifers, yellow spores, teliospores, and aeciospores of yellow spore­bearing (uredinial) pustules spots occur on needles as the aecial stage M. occidentalis are generally larger than (figs. 27.1 and 27.2). When these pustules develops. When mature, the aecia rupture those of M. medusae. 98 Forest Nursery Pests Hardwood Diseases 27. Poplar Leaf Rusts to adjacent leaves, thus intensifying Selected References the disease on poplar hosts throughout the growing season. In the fall telia Innes, L.; Marchand, L.; Frey, P.; Bourassa, M.; Hamelin, R.C. 2004. First report of are produced, completing the annual Melampsora larici­populina on Populus disease cycle. Since both aeciospores and spp. in eastern North America. Plant Disease. urediniospores are windborne, infection 88: 85. of poplars can occur at considerable dis­ tances from conifer hosts. In areas of the Moltzan, B.D.; Stack, R.W.; Mason, P.A.; Ostry, M.E. 1993. First report of Melampsora Southern United States where ornamental occidentalis on Populus trichocarpa in the larch is grown, leaf rust epidemics can Central United States. Plant Disease. 77: 953. occur without need for windborne spores from larch in more northerly locations. Newcombe, G.; Chastagner, G.A. 1993. First report of the Eurasian poplar leaf rust fungus Melampsora larici­populina in North Control America. Plant Disease. 77: 532–535. Newcombe, G.; Chastagner, G.A. 1993. A Prevention Figure 27.3—Melampsora medusae pycniospore leaf rust epidemic of hybrid poplar along the Photo by Michael E. Ostry, lower Columbia River caused by Melampsora droplets on needles of larch. Planting poplar species and clones USDA Forest Service. medusae. Plant Disease. 77: 528–531. selected for resistance to the local Melampsora species population is the Newcombe, G.; Stirling, B.; McDonald, Biology most effective practice. Growing poplars S.; Bradshaw, Jr., H.D. 2000. Melampsora near coniferous alternate hosts will result xcolumbiana, a natural hybrid of M. medusae and M. occidentalis. Mycological Research. Melampsora species require a conifer­ in infection earlier in the season and 104: 261–274. ous alternate host to complete their life increased disease severity. In the South, cycle. The conifer species varies with remove susceptible evergreen poplars Ostry, M.E.; Wilson, L.F.; McNabb, Jr., H.S.; the rust species. Telia are produced on to reduce the amount of overwintering Moore, L.M. 1989. A guide to insect, disease, poplar leaves in the fall and appear as uredinia. Leaf microflora and saprophytic and animal pests of poplars. Agriculture Handbook 677. Washington, DC: USDA brown to black, crusty patches on fallen microorganisms have been shown to be Forest Service. 118 p. leaves. In spring, the teliospores in these antagonistic to rusts and may function fallen leaves germinate and produce as natural biological control agents. Shain, L. 1988. Evidence for formae speciales basidiospores, which are windblown to Planting large, monoclonal beds should in the poplar leaf rust fungus, Melampsora the developing needles of coniferous be avoided. This precautionary measure medusae. Mycologia. 80: 729–732. hosts where infection takes place. The minimizes a new rust species or race from Shain, L.; Filer, Jr., T.H. 1989. Cottonwood first fungal structures to develop on becoming damaging in the future. leaf rusts. In: Cordell, C.E.; Anderson, R.L.; infected needles are the pycnia, which Hoffard, W.H.; Landis, T.D.; Smith, Jr., R.S.; produce haploid spores (pycniospores) Chemical Toko, H.V., tech. coords. Forest nursery pests. associated with sexual reproduction. In Agriculture Handbook 680. Washington, DC: USDA Forest Service: 90–91. summer, shortly after the pycnia develop, Application of fungicides labeled aeciospores are produced on the needles for control of Melampsora on poplar Stack, R.W.; Ostry, M.E. 1989. Melampsora and are windblown to poplar leaves. can reduce infection of leaves. Begin leaf rust on Populus in the North Central Yellow­orange uredinia pustules develop applying fungicidal sprays in the summer United States. In: Merrill, W.; Ostry, M.E., on infected poplar leaves and release when conditions are favorable for spore eds. Proceedings, IUFRO Recent Research on Foliage Diseases. GTR­WO­56. Washington, urediniospores that are carried by wind development, dispersal, and infection. DC: USDA Forest Service. 119–124. Forest Nursery Pests 99.
Load more

Recommended publications
  • Melampsora Medusae
    European and Mediterranean Plant Protection Organization PM 7/93 (1) Organisation Europe´enne et Me´diterrane´enne pour la Protection des Plantes Diagnostics Diagnostic Melampsora medusae Specific scope Specific approval and amendment This standard describes a diagnostic protocol for Melampsora Approved in 2009–09. medusae1 Populus trichocarpa, and their interspecific hybrids (Frey et al., Introduction 2005). In Europe, most of the cultivated poplars are P. · eur- Melampsora medusae Thu¨men is one of the causal agents of americana (P. deltoides · P. nigra)andP. · interamericana poplar rust. The main species involved in this disease in Europe (P. trichocarpa · P. deltoides) hybrids. In addition, Shain (1988) on cultivated poplars are Melampsora larici-populina and showed evidence for the existence of two formae speciales within Melampsora allii-populina. All three species cause abundant M. medusae and named them M. medusae f. sp. deltoidae and uredinia production on leaves, which can lead to premature M. medusae f. sp. tremuloidae according to their primary host, defoliation and growth reduction. After several years of severe Populus deltoides and Populus tremuloides, respectively. Neither infection leading to repeated defoliation, the disease may predis- the EU directive, nor the EPPO make the distinction between pose the trees to dieback or even death for the younger trees. these two formae speciales but only refer to M. medusae.Not- Melampsora rust is a very common disease of poplar trees, which withstanding, since M. medusae was only reported in Europe on can cause severe economic losses in commercial poplar cultiva- poplars from the sections Aigeiros and Tacamahaca,andin tion because of the emergence and spread of new pathotypes of respect with the host specialization, it can be stated that only M.
    [Show full text]
  • Evolution of Isoprenyl Diphosphate Synthase-Like Terpene
    www.nature.com/scientificreports OPEN Evolution of isoprenyl diphosphate synthase‑like terpene synthases in fungi Guo Wei1, Franziska Eberl2, Xinlu Chen1, Chi Zhang1, Sybille B. Unsicker2, Tobias G. Köllner2, Jonathan Gershenzon2 & Feng Chen1* Terpene synthases (TPSs) and trans‑isoprenyl diphosphate synthases (IDSs) are among the core enzymes for creating the enormous diversity of terpenoids. Despite having no sequence homology, TPSs and IDSs share a conserved “α terpenoid synthase fold” and a trinuclear metal cluster for catalysis, implying a common ancestry with TPSs hypothesized to evolve from IDSs anciently. Here we report on the identifcation and functional characterization of novel IDS-like TPSs (ILTPSs) in fungi that evolved from IDS relatively recently, indicating recurrent evolution of TPSs from IDSs. Through large-scale bioinformatic analyses of fungal IDSs, putative ILTPSs that belong to the geranylgeranyl diphosphate synthase (GGDPS) family of IDSs were identifed in three species of Melampsora. Among the GGDPS family of the two Melampsora species experimentally characterized, one enzyme was verifed to be bona fde GGDPS and all others were demonstrated to function as TPSs. Melampsora ILTPSs displayed kinetic parameters similar to those of classic TPSs. Key residues underlying the determination of GGDPS versus ILTPS activity and functional divergence of ILTPSs were identifed. Phylogenetic analysis implies a recent origination of these ILTPSs from a GGDPS progenitor in fungi, after the split of Melampsora from other genera within the class of Pucciniomycetes. For the poplar leaf rust fungus Melampsora larici-populina, the transcripts of its ILTPS genes were detected in infected poplar leaves, suggesting possible involvement of these recently evolved ILTPS genes in the infection process.
    [Show full text]
  • Forest Health Conditions in Alaska 2020
    Forest Service U.S. DEPARTMENT OF AGRICULTURE Alaska Region | R10-PR-046 | April 2021 Forest Health Conditions in Alaska - 2020 A Forest Health Protection Report U.S. Department of Agriculture, Forest Service, State & Private Forestry, Alaska Region Karl Dalla Rosa, Acting Director for State & Private Forestry, 1220 SW Third Avenue, Portland, OR 97204, [email protected] Michael Shephard, Deputy Director State & Private Forestry, 161 East 1st Avenue, Door 8, Anchorage, AK 99501, [email protected] Jason Anderson, Acting Deputy Director State & Private Forestry, 161 East 1st Avenue, Door 8, Anchorage, AK 99501, [email protected] Alaska Forest Health Specialists Forest Service, Forest Health Protection, http://www.fs.fed.us/r10/spf/fhp/ Anchorage, Southcentral Field Office 161 East 1st Avenue, Door 8, Anchorage, AK 99501 Phone: (907) 743-9451 Fax: (907) 743-9479 Betty Charnon, Invasive Plants, FHM, Pesticides, [email protected]; Jessie Moan, Entomologist, [email protected]; Steve Swenson, Biological Science Technician, [email protected] Fairbanks, Interior Field Office 3700 Airport Way, Fairbanks, AK 99709 Phone: (907) 451-2799, Fax: (907) 451-2690 Sydney Brannoch, Entomologist, [email protected]; Garret Dubois, Biological Science Technician, [email protected]; Lori Winton, Plant Pathologist, [email protected] Juneau, Southeast Field Office 11175 Auke Lake Way, Juneau, AK 99801 Phone: (907) 586-8811; Fax: (907) 586-7848 Isaac Dell, Biological Scientist, [email protected]; Elizabeth Graham, Entomologist, [email protected]; Karen Hutten, Aerial Survey Program Manager, [email protected]; Robin Mulvey, Plant Pathologist, [email protected] State of Alaska, Department of Natural Resources Division of Forestry 550 W 7th Avenue, Suite 1450, Anchorage, AK 99501 Phone: (907) 269-8460; Fax: (907) 269-8931 Jason Moan, Forest Health Program Coordinator, [email protected]; Martin Schoofs, Forest Health Forester, [email protected] University of Alaska Fairbanks Cooperative Extension Service 219 E.
    [Show full text]
  • A New Species of Melampsora Rust on Salix Elbursensis from Iran
    For. Path. doi: 10.1111/j.1439-0329.2010.00699.x Ó 2010 Blackwell Verlag GmbH A new species of Melampsora rust on Salix elbursensis from Iran By S. M. Damadi1,5, M. H. Pei2, J. A. Smith3 and M. Abbasi4 1Department of Plant Protection, Faculty of Agriculture, University of Maragheh, Maragheh, Iran; 2Rothamsted Research, Harpenden, Hertfordshire, UK; 3School of Forest Resources and Conservation, University of Florida, Gainesville, Florida, USA; 4Plant Pests & Diseases Research Institute, Tehran, Iran; 5E-mail: [email protected] (for correspondence) Summary A rust fungus was found causing stem cankers on 1- to 5-year-old stems of Salix elbursensis in the north west of Iran. The rust also forms uredinia on leaves and flowers of the host willow. Light and scanning electron microscopy revealed that the new rust is morphologically distinct from several Melampsora species occurring on the willows taxonomically close to S. elbursensis, but indistinguish- able from Melampsora larici-epitea. Examination of the internal transcribed spacer (ITS) region of the ribosomal DNA suggested that the rust fungus is phylogenetically close to Melampsora allii-populina and Melampsora pruinosae on Populus spp. Based on both the morphological characteristics and the ITS sequence data, the rust is described as a new species – Melampsora iranica sp. nov. 1 Introduction The genus Melampsora was established by Castagne in 1843 based on the rust on Euphorbia, Melampsora euphorbiae (Schub.) Cast. (Castagne 1843). The main character- istic of the genus Melampsora is the formation of ÔnakedÕ uredinia and crust-like telia that comprise sessile, laterally adherent single-celled teliospores. Of some 80 Melampsora spp.
    [Show full text]
  • New Reports of Melampsora Rust (Pucciniomycetes) on the Salix Retusa Complex in Balkan Countries
    (2020) 44 (1): 89-93 DOI: https://doi.org/10.2298/BOTSERB2001089S journal homepage: botanicaserbica.bio.bg.ac.rs Original Scientific Report New reports of Melampsora rust (Pucciniomycetes) on the Salix retusa complex in Balkan countries Miloš Stupar✳, Milica Ljaljević Grbić, Jelena Vukojević and Dmitar Lakušić University of Belgrade, Faculty of Biology, Institute of Botany and Botanical Garden “Jevremovac”, Takovska 43, 11000 Belgrade, Serbia ✳ correspondence: [email protected] Keywords: ABSTRACT: plant pathogen, distribution, Melampsora epitea, known to cause rust on the complex of Salix retusa prostrate Melampsora epitea, basidiomycete, willows distributed in the subalpine and alpine belt of the mountains of Central snow willows Europe, is here documented for the first time in Montenegro and North Macedonia growing at six localities. It is not new for Serbia, but the records come from a newly reported host, namely Salix serpyllifolia. The pathogen’s distribution presumably is UDC: 528.28:582.681.81(234.42) wider than initially believed, and further surveys need to be conducted. Received: 09 January 2020 Revision accepted: 04 February 2020 During field investigation of the complex of Salix retusa were collected, placed in bags and transported to a labo- (family Salicaceae) on the Balkan Peninsula, six popula- ratory in the Department of Algology, Mycology and Li- tions with many individuals infected with rust fungus chenology of Faculty of Biology, University of Belgrade for were documented (Fig. 1). proper screening of symptoms, documented and used for The complex of Salix retusa includes S. retusa L. (s.str), further analyses by light and scanning microscopy. Symp- S.
    [Show full text]
  • Ray G. Woods, R. Nigel Stringer, Debbie A. Evans and Arthur O. Chater
    Ray G. Woods, R. Nigel Stringer, Debbie A. Evans and Arthur O. Chater Summary The rust fungi are a group of specialised plant pathogens. Conserving them seems to fly in the face of reason. Yet as our population grows and food supplies become more precarious, controlling pathogens of crop plants becomes more imperative. Breeding resistance genes into such plants has proved to be the most cost effective solution. Such resistance genes evolve only in plants challenged by pathogens. We hope this report will assist in prioritising the conservation of natural ecosystems and traditional agro-ecosystems that are likely to be the richest sources of resistance genes. Despite its small size (11% of mainland Britain) Wales has supported 225 rust fungi taxa (including 199 species) representing 78% of the total British mainland rust species. For the first time using widely accepted international criteria and data collected from a number of mycologists and institutions, a Welsh regional threat status is offered for all native Welsh rust taxa. The results are compared with other published Red Lists for Wales. Information is also supplied in the form of a census catalogue, detailing the rust taxa recorded from each of the 13 Welsh vice-counties. Of the 225 rust taxa so far recorded from Wales 7 are probably extinct (3% of the total), and 39 (18%) are threatened with extinction. Of this latter total 13 taxa (6%) are considered to be Critically Endangered, 15 (7%) to be Endangered and 13 (6%) to be Vulnerable. A further 20 taxa (9%) are Near Threatened, whilst 15 taxa (7%) lacked sufficient data to permit evaluation.
    [Show full text]
  • Working Party on Poplar and Willow Diseases
    WORKING PARTY ON POPLAR AND WILLOW DISEASES 159 160 HOST-RANGE STUDIES OF MELAMPSORA ON SALIX IN THE PACIFIC NORTHWEST REGION OF THE UNITED STATES Chandalin Bennett1, George Newcombe, Catherine Aime Melampsora is known as an important cause of disease on willows throughout the world. Even so, little is known about the occurrence, distribution, and specific hosts of these leaf rusts in North America. Current classification places all willow rusts occurring in North America into the species complex Melampsora epitea Thuem. This is a result of supposed morphological continuity throughout the complex. Several lines of study have been initiated in an effort to understand what is represented by this complex on a regional scale. Host-range inoculation experiments of Melampsora on Salix are the main components of this baseline study. Although wild collections are still in progress, a preliminary inoculation has been performed with rust from Salix sitchensis. Ten different Salix species that occur throughout the Pacific Northwest (PNW) region of the United States were used as test plants. It was found that this Melampsora isolate was able to infect across the range of its host plant, which represents six geographically distinct S. sitchensis populations throughout Washington and Idaho states. Three others: Salix spp., S. wolfii, S. bebbiana, and S. scouleriana were also susceptible to this inoculum, although both S. bebbiana and S. scouleriana displayed an hypersensitive response and prolonged latent period (> 15 days). Five other Salix species - S. geyeriana, S. exigua, S. melanopsis, S. alba, and S. eriocephala - from locations throughout this region were resistant to the inoculum. These preliminary results clearly demonstrate that Melampsora is host specific and that certain populations of Salix are resistant to this particular isolate.
    [Show full text]
  • Common Larch-Willow Rust -Melampsora Capraearum a Number of Rust Fungi Infect Larch and Willow Trees
    U.S. Department of Agriculture, Agricultural Research Service Systematic Mycology and Microbiology Laboratory - Invasive Fungi Fact Sheets Common larch-willow rust -Melampsora capraearum A number of rust fungi infect larch and willow trees. If the teliospores are present on upper surface of willow leaves, Melampsora caprearum can be easily differentiated by the thickened apex of the teliospores. Also on willow, the uredinial stage is more difficult to distinguish from other species of Melampsora. The inconspicuous spermagonial and aecial stages occur on larch in spring. Recent molecular studies have confirmed that these are distinct species that can be identified using molecular diagnostic tools (Nakamura et al. 1998, Pei et al. 2005). Pei & McCracken (2005) present a recent account of these rust fungi. Melampsora caprearum is the most common species of this genus on larch in Europe. Melampsora capraearum Thum. 1879 Spermogonia amphigenous, type 3 (Hiratsuka, 1992). Aecia hypophyllous, pale orange; aeciospores globose or broadly ellipsoid, 15-25 × 12-20 µm, finely and densely verrucose, walls 1.5-2 µm, thick, germ pores scattered. Uredinia hypophyllous, occasionally epiphyllous, 1-3 mm; urediniospores globose or broadly ellipsoid, 14-26 × 13-23 µm, walls 2-4 µm thick, distantly echinulate, germ pores scattered; paraphyses capitate, 50-60 x 18-30 µm, walls thickened at apex, up to 6 µm. Telia epiphyllous, subcuticular, 1 mm or more wide, dark reddish-brown; teliospores 25-45 × 7-17 µm, walls 1 µm thick at side, 5-10 µm thick above, with an apical germ pore. See Hiratsuka (1992) and for a more detailed description. Host range: Spermagonial and aecial stages on various species of Larix, mostly commonly on Larix decidua and L.
    [Show full text]
  • Melampsora Spp.) David L
    Comparative analysis of secreted protein evolution using expressed sequence tags from four poplar leaf rusts (Melampsora spp.) David L. Joly, Nicolas Feau, Philippe Tanguay, Richard Hamelin To cite this version: David L. Joly, Nicolas Feau, Philippe Tanguay, Richard Hamelin. Comparative analysis of secreted protein evolution using expressed sequence tags from four poplar leaf rusts (Melampsora spp.). BMC Genomics, BioMed Central, 2010, 11, 16 p. 10.1186/1471-2164-11-422. hal-02660329 HAL Id: hal-02660329 https://hal.inrae.fr/hal-02660329 Submitted on 30 May 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Joly et al. BMC Genomics 2010, 11:422 http://www.biomedcentral.com/1471-2164/11/422 RESEARCH ARTICLE Open Access Comparative analysis of secreted protein evolution using expressed sequence tags from four poplar leaf rusts (Melampsora spp.) David L Joly1, Nicolas Feau1,3, Philippe Tanguay1, Richard C Hamelin1,2* Abstract Background: Obligate biotrophs such as rust fungi are believed to establish long-term relationships by modulating plant defenses through a plethora of effector proteins, whose most recognizable feature is the presence of a signal peptide for secretion. Since the phenotypes of these effectors extend to host cells, their genes are expected to be under accelerated evolution stimulated by host-pathogen coevolutionary arms races.
    [Show full text]
  • Leaf Rusts of Poplars and Willows in the Midwest
    report on RPD No. 605 PLANT February 1990 DEPARTMENT OF CROP SCIENCES DISEASE UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN LEAF RUSTS OF POPLARS AND WILLOWS IN THE MIDWEST In the Midwest, premature defoliation of willows, poplars, aspens, and cottonwoods is often caused by three or four leaf rust fungi in the genus Malampsora. All North American willow rusts are currently assigned to the “group species” M. epitea mainly because they are morphologically indistinguishable from each other in their telial and uredinial states on willows. This group species includes the synonyms M. abieti-capracearum and M. paradoxa (also known as M. bigelowii) which occur in the Midwest. The leaf rust fungi that attacks poplars are named M. medusae (synonym M. albertensis and M. abietis- Figure 1. Leaf rust on poplar. canadensis. The approximate host ranges of these fungi in the Midwest are given in Tables 1 and 2. In wet years, young trees may be severely defoliated, suppressing growth 30 percent or more. In susceptible bottomland cottonwood stands, continued defoliation of successive flushes of growth by leaf rusts decreases vigor and indirectly increases the likelihood of winter injury as well as susceptibility to other diseases, such as Cytospora, Dothichiza, and Phomopsis cankers. Epidemics of leaf rusts are favored by growing susceptible clones of poplars and willows in crowded, monocultural stands where air movement is restricted. Table 1. Willows (Salix species) susceptible to Melampsora epitea (equals M. paradoxa and M. abieti- capracearum) in the Midwest Willow (Salix) Babylon weeping (S. babylonica) Osier, common or basket (S. viminalis) Bay or laurel-leaved (S.
    [Show full text]
  • LIFE CYCLE and GENETIC DIVERSITY of WILLOW RUSTS (Melampsora Spp.) in EUROPE
    ACTA AGROBOTANICA Vol. 64 (1): 3–10 2011 LIFE CYCLE AND GENETIC DIVERSITY OF WILLOW RUSTS (Melampsora spp.) IN EUROPE Joanna Ciszewska-Marciniak, Małgorzata Jędryczka Institute of Plant Genetics, Polish Academy of Sciences, Poznań, Poland e-mail: [email protected] Received: 19.11.2010 Abstract energy (Szczukowski et al. 2005; T rybush et The paper is a review of classical and recent studies on al. 2008), the study of its pathogens is regarded as sig- willow rusts in Europe, with special reference to short rotation nificant. coppice willows used for biomass production, such as common osier willow (Salix viminalis L.). The review presents the taxo- CLASSIFICATION OF RUST FUNGI nomic classification of rust fungi from the genus Melampsora spp. We present a list of telial hosts (genus Salix) as well as ae- The rust fungi belong to the class Pucciniomyce- cial hosts for different rust species. The life cycle of this fungal tes and the order Pucciniales. They contain about 7,000 pathogen is described in detail from the epidemiological and species (Webster and Weber, 2007), which are genetic point of view. The DNA polymorphism of M. larici- grouped in more than 100 genera (Cummins and epitea, the rust species most responsible for severe yield losses Hiratsuka, 1983; Ono and Aime, 2006). The po- of plant biomass, is characterised based on RAPD, AFLP and pular name “rust fungi” refers to the reddish – brown RFLP-PCR methods. colour of urediniospores which are produced in dense pustules on the host plant surface (leaf or stem), giving Key words: willow, Salix sp., rust, Melampsora spp., life cyc- them a “rusted” appearance.
    [Show full text]
  • Introduction to Rust Diseases
    Introduction to Rust Diseases Specialized foliage and/or canker diseases often with alternate hosts Rust diseases are grouped based on the taxonomic classification of the pathogens.They are fungi in the phylum Basidiomycota, class Pucciniomycetes, and order Pucciniales. Rusts are all obligate parasites that depend on the living cells of their hosts. Initially, they produce structures (haustoria) that grow into their hosts’ living cells, from which they derive nutrients. The diseases caused by this group are varied. Most of the rust fungi initially infect and cause diseases of foliage. However, some spread into branches and stems, colonizing the phloem and cambium. Rusts cause cankers (dis- eases of the bark), galls, brooms, foliage diseases, and/or cone diseases. The majority of the rust diseases in this Region are native pathogens, with the exception of white pine blister rust. Table 9 provides examples of some of the most damaging and/or common rusts in the region (figs. 1-7). However, many other rusts occur within the Rocky Mountain Region. Signs and Symptoms—The common name, “rusts,” comes from the rust-like appearance of the various spore structures that are often rust-colored, yellow, and/or orange. These brightly colored signs help to distinguish rusts from other diseases. If signs are not present, symptoms may look like other foliage or canker diseases, with dis- colored foliage or branch flagging (faded and dying branches). Stem rusts often can be identified by the host and shape of the cankers or galls. The cankers usually have distinctive roughness on their margin that are the remains of earlier fruiting structures.
    [Show full text]