DOCSLIB.ORG

The Pathogenicity and Seasonal Development of Gymnosporangium

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Pathogenicity and Seasonal Development of Gymnosporangium Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1931 The ap thogenicity and seasonal development of Gymnosporangium in Iowa Donald E. Bliss Iowa State College Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Agriculture Commons, Botany Commons, and the Plant Pathology Commons Recommended Citation Bliss, Donald E., "The ap thogenicity and seasonal development of Gymnosporangium in Iowa " (1931). Retrospective Theses and Dissertations. 14209. https://lib.dr.iastate.edu/rtd/14209 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMl films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMl a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g.. maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overiaps. ProQuest Information and Learning 300 North Zeeb Road, Ann Arbor, Ml 48105-1346 USA 800-521-0500 NOTE TO USERS This reproduction is the best copy available. UMI' THE PATHOGENICITY AND SEASONAL DEVELOPMENT OP GYMOSPORANGIDM IN IOWA By Donald E. Bliss A Thesis Submitted to the Gradmte Faculty for the Degree of ? PHILOSOPHy Signature was redacted for privacy. Signature was redacted for privacy. E^d of Major Department Signature was redacted for privacy. Dean of Graduate College Iowa State College Ames, Iowa 1931 UMI Number: DP14399 iMi JMI Microform DP14399 Copyright 2006 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 TABES OF CONTEKTS P&ge I. Introduction 4 II. Pertinent Literature 7 A. Species of Gymnosporangium in Iowa 7 B. Seasonal Development 9 C. Pathogenicity of Gymnosporangium juniperi- virginianae and G. globosum T»T7 17 D. Control by isolation from red cedars 48 III. The Species of Gymnosporangiim in Iowa 50 IV. Studies on Seasonal Development 77 A. Seasonal development of Gymnosporangitm juniperi -virginianae 77 1. Notes on development of rust, 1927 ....... 78 2. Notes on development of rust, 1928 79 3. Notes on development of rust, 1929 80 (a) Systemic infection in Pyrus ioensis .. 81 (b) Appearance of galls on red cedar ,.... 83 (c) Dormancy in rust mycelium. 85 4. Notes on development of rust, 1930 ....... 86 (a) Development of rust galls in the greenhouse 87 5. Experimental,evidence on the life cycle ., 92 6. Experiments to prolong the pericd of via­ bility of teleutospores 95 7. Conditions favorable for the sporulation of galls 96 8. The morphology of germinating teleuto­ spores and sporidia 98 9. Germination of aecidiospores 108 10. Morphology of aecidiospores and their germ tubes 115 B. Seasonal development of Gymnospora.ngiiaii lo^siffii 117 f, Observations in the open 117 2. Development of galls in the greenhouse ... 122 3. Germination of teleutospores 133 4. Germination of aecidiospores 133 V« Studies on Pathogenicity 141 A. The pathogenicity of Gymnosporangium iuniperi-virginianae 143 1, Relative susceptibility of cultivated apples and crabapples 144 -3- Page (a) Extent of loss from leaf spots ....... 146 (1) Relation between the per cent of leaves infected and the extent of loss 193 (h) Occurrence of stem cankers 1S7 (c) The homogeneity of groups of apple varieties in respect to relative sus­ ceptibility 197 2, Relative susceptibility of other hosts ... 205 (s) Aecidial hosts 206 (b) Teleuto hosts 209 3. Physiologic specialization 219 (aV Materials used 222 (b) Method of inoculation 227 (c) Greenhouse trials 228 (d) Field trials,. 233 The pathaagenicity of G. globosum 244 1« Host plants and their relative suscepti­ bility 245 2. Evidence of physiologic specialization ... 248 VI. Studies on the Effect of Isolation from Red Cedar Trees on the Amotint of Cedar-Apple Rast on Apples 253 VII* Discussion 258 VIII. Summary 263 IX. Literature Cited 267 -4. INTRODUCTION i Because cedar-apple mist can only "be controlled success­ fully by the isolation of apples from red cedars, this fungous ! parasite presents a peculiar problem in Iowa where both of its : hosts are trees of value. The red cedar, Juniperus virginiana L., is the only native conifer which is distributed widely throu^out the state. It is cultivated conmonly for shelter belts on farmsteads and its numerous horticultural varieties are utilized by the landscape gardener because of their rare aesthetic worth. The red cedar, aside from its association with the rust fungi, is a desirable plant in Iowa because of its adaptability, utility and beauty. seventy per cent of the 2,840,000 apple trees in Iowa are in home plantings. Vfnere orcharding is practiced commercially the comparative value of apples is much greater than that of red cedars, but in other localities this may not be true. The epidemic of cedar-apple rust in 1923 was one of the most severe outbreaks in many years and caused an estimated loss of $290,000 in Iowa. Orchardists in Harrison County sus­ tained such damage that agitation was started to control the disease by legislation against the red cedar. This move was considered by the officials who are mostly concerned with the 5- control of plant diseases in Iowa but to them the immediate passage of an anti-red-cedar law seemed unadvisable. Instead, a program involving local cooperation betv;een the orchardists and their neigjhbors was substituted and a more thorough investi­ gation was planned. Additional information was needed regarding the prevalence and taxonomy of the cedar rust fungi in Iowa, Their host ranges were poorly defined and many conflicting statements were found regarding the relative susceptibility of these hosts. The latter was especially true in the case of Gsminosporangium juniperi-virginianae Schw. on varieties of cultivated apple. It was also desirable to investigate the effectiveness of con­ trol by the isolation of apples from red cedars. In the event that a rust-resistant jiiniper could be discovered, the problem of disease control mi^t be simplified greatly. It was for the purpose of obtaining information on these problems that the present investigation was started. Most of the field work was done in the nurseries at Shenandoah. Labora­ tory and greenhouse experiments were conducted at Ames and several collecting trips were made over the state. The data were taken during the years 1927 to 1931, althou^ the project was not begun officially until the summer of 1928. Cedar-apple mst was studied from four angles, the pur­ poses of which may be stated as follows: (a) To siimmarize the 6- present knowledge of the genus Gymnosporangium in Iowa as to its geographic distribution, prevalence, host range and mor­ phology. (b) To investigate the seasonal development of Gymnosporangium juniperi-virginianae Schw, and G. globosim pari, and the diseases which they cause, (c) To determine the relative susceptibility of species and varieties of Poma- ceae and Juniperaceae to G. juniperi-virginianae and G. glo- bosum in Iowa; to measure the extent of injury caused; and to compare the pathogenicity of the fungi causing cedar-apple rust in Iowa with that of similar rusts from other states, (d) To measure the effect of isolation from red cedar trees on the amount of cedar-apple rust on apples. 7- PBRTIIEHT LITBRATURE Cedar-apple rust has been the subject of much investiga­ tion in this country since 1880 v/hen Farlow (52) published "The Gymnosporangia or cedar-apples of the United States." Kern (63), Giddings and Berg (40), Reed and Crabill (81), Jones and Bartholomew (61) and Weimer (98, 99) have adequately re­ viewed the literature up to 1917. No attempt will be made at this time to mention all of the literature on cedar-apple rust but only those contributions which bear directly on the problems at hand. To parallel the arrangement of the data v/laich follow, the review of literature has been divided also into four parts. SPECIES OP C-WiNOSPORANC-IUM III lOif/A In his "Preliminary list of Iowa Uredineae" Arthur (6) mentions collections of the teleuto stage of Gymnosporangium clavariaeforme D C., G. germinale (Schw.) Kern.(G« clavipes C« and P.), G. juniperi-virginianae Schw. (G. inacropus Lk.) and of two aecidial forms, Roestelia lacerata ?r. and Roes» peni- cillata Pr# In 1892 Pammel (71) discovered G. globosum Pari, on red cedar near Ames. Wilson (101) added G. corniculans Kern 6- and G. nidus-avis Thax. to the list in 1910. Compilations of the collections in Iowa are given by Arthur (9) and more re- i cently by Gilman and Archer (44)» In 1905 Pammel (73) figured five species of Gymnosporangium i • known in lowa at that time. In fig. 11, page 55, there are pen ! drawings of the aecidia of G. jxmiperi-virginianae (Roestelia : pyrata (Schw.) Ihax.) on Crataegus bipinnatifida and Mercer : crab (Pyrus ioensls).
Load more

Recommended publications
  • Apples Catalogue 2019
    ADAMS PEARMAIN Herefordshire, England 1862 Oct 15 Nov Mar 14 Adams Pearmain is a an old-fashioned late dessert apple, one of the most popular varieties in Victorian England. It has an attractive 'pearmain' shape. This is a fairly dry apple - which is perhaps not regarded as a desirable attribute today. In spite of this it is actually a very enjoyable apple, with a rich aromatic flavour which in apple terms is usually described as Although it had 'shelf appeal' for the Victorian housewife, its autumnal colouring is probably too subdued to compete with the bright young things of the modern supermarket shelves. Perhaps this is part of its appeal; it recalls a bygone era where subtlety of flavour was appreciated - a lovely apple to savour in front of an open fire on a cold winter's day. Tree hardy. Does will in all soils, even clay. AERLIE RED FLESH (Hidden Rose, Mountain Rose) California 1930’s 19 20 20 Cook Oct 20 15 An amazing red fleshed apple, discovered in Aerlie, Oregon, which may be the best of all red fleshed varieties and indeed would be an outstandingly delicious apple no matter what color the flesh is. A choice seedling, Aerlie Red Flesh has a beautiful yellow skin with pale whitish dots, but it is inside that it excels. Deep rose red flesh, juicy, crisp, hard, sugary and richly flavored, ripening late (October) and keeping throughout the winter. The late Conrad Gemmer, an astute observer of apples with 500 varieties in his collection, rated Hidden Rose an outstanding variety of top quality.
    [Show full text]
  • Dusting Versus Spraying Apple Orchards in Ohio
    BULLETIN 527 AUGUST, 1933 Dusting Versus Spraying Apple Orchards in Ohio F. H. Ballou and I. P. Lewis • OHIO AGRICULTURAL EXPERIMENT STATION Wooster, Ohio This page intentionally blank. DUSTING VERSUS SPRAYING APPLE ORCHARDS IN OHIO . INTRODUCTION F. :U:. BALLOU .AliD I. I'. LEWIS In response to a special request from the organized fruit growers of Ohio the Department of Horticulture of the Ohio Experiment Station began, in the spring of 1926, a series of experiments in dusting versus spraying apple orchards for prevention of injury to foliage and fruit by fungous diseases and insect pests. This series of dusting versus spraying experiments was carried on in eastern, central, northeastern, and southeastern Ohio. The five widely separated projects were located as follows: The Belmont County Experiment Farm, the Dale View Test Orchards (Licking County), the Mahoning County Experiment Farm, the Southeastern Experiment Farm (Meigs County), and the Washington County Experiment Farm. The orchards in Belmont, Licking, and Washington Counties are very favorably situated in hilly sections of the State and, for the most part, occupy areas of ground of such elevation as affords unusual frost protection to buds, blossoms, and newly set fruit. No losses of fruit from cold occurred in these orchards during the full term of the experiment. The orchard at the Mahoning County Experiment Farm occupies ground of moderate elevation, which affords fairly satisfactory cold-air drainage. In the spring of 1929 a partial loss of the apple crop was sustained by reason of freezing temperature immediately preceding the period of open blossoms. However, there was sufficient production of fruit to permit securing grades and counts in all of the variously dusted and sprayed plots.
    [Show full text]
  • Apple Varieties in Maine Frederick Charles Bradford
    The University of Maine DigitalCommons@UMaine Electronic Theses and Dissertations Fogler Library 6-1911 Apple Varieties in Maine Frederick Charles Bradford Follow this and additional works at: http://digitalcommons.library.umaine.edu/etd Part of the Agriculture Commons Recommended Citation Bradford, Frederick Charles, "Apple Varieties in Maine" (1911). Electronic Theses and Dissertations. 2384. http://digitalcommons.library.umaine.edu/etd/2384 This Open-Access Thesis is brought to you for free and open access by DigitalCommons@UMaine. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of DigitalCommons@UMaine. A thesis submitted to the faculty of the University of Maine in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN AGRICULTURE by FREDERICK CHARLES BRADFORD, B. S . Orono, Maine. June, 1911. 8 2 8 5 INTRODUCTION The following pages represent an effort to trace the causes of the changing procession of varieties of apples grown in Maine. To this end the history of fruit growing in Maine has been carefully studied, largely through the Agricultural Reports from 1850 to 1909 and the columns of the Maine Farmer fran 1838 to 1875. The inquiry has been confined as rigidly as possible to this state, out­ side sources being referred to only for sake of compari­ son. Rather incidentally, soil influences, modifications due to climate, etc., have been considered. Naturally* since the inquiry was limited to printed record, nothing new has been discovered in this study. Perhaps a somewhat new point of view has been achieved. And, since early Maine pomological literature has been rather neglected by our leading writers, some few forgot­ ten facts have been exhumed.
    [Show full text]
  • Variety Description Origin Approximate Ripening Uses
    Approximate Variety Description Origin Ripening Uses Yellow Transparent Tart, crisp Imported from Russia by USDA in 1870s Early July All-purpose Lodi Tart, somewhat firm New York, Early 1900s. Montgomery x Transparent. Early July Baking, sauce Pristine Sweet-tart PRI (Purdue Rutgers Illinois) release, 1994. Mid-late July All-purpose Dandee Red Sweet-tart, semi-tender New Ohio variety. An improved PaulaRed type. Early August Eating, cooking Redfree Mildly tart and crunchy PRI release, 1981. Early-mid August Eating Sansa Sweet, crunchy, juicy Japan, 1988. Akane x Gala. Mid August Eating Ginger Gold G. Delicious type, tangier G Delicious seedling found in Virginia, late 1960s. Mid August All-purpose Zestar! Sweet-tart, crunchy, juicy U Minn, 1999. State Fair x MN 1691. Mid August Eating, cooking St Edmund's Pippin Juicy, crisp, rich flavor From Bury St Edmunds, 1870. Mid August Eating, cider Chenango Strawberry Mildly tart, berry flavors 1850s, Chenango County, NY Mid August Eating, cooking Summer Rambo Juicy, tart, aromatic 16th century, Rambure, France. Mid-late August Eating, sauce Honeycrisp Sweet, very crunchy, juicy U Minn, 1991. Unknown parentage. Late Aug.-early Sept. Eating Burgundy Tart, crisp 1974, from NY state Late Aug.-early Sept. All-purpose Blondee Sweet, crunchy, juicy New Ohio apple. Related to Gala. Late Aug.-early Sept. Eating Gala Sweet, crisp New Zealand, 1934. Golden Delicious x Cox Orange. Late Aug.-early Sept. Eating Swiss Gourmet Sweet-tart, juicy Switzerland. Golden x Idared. Late Aug.-early Sept. All-purpose Golden Supreme Sweet, Golden Delcious type Idaho, 1960. Golden Delicious seedling Early September Eating, cooking Pink Pearl Sweet-tart, bright pink flesh California, 1944, developed from Surprise Early September All-purpose Autumn Crisp Juicy, slow to brown Golden Delicious x Monroe.
    [Show full text]
  • Pear Trellis Rust, a New Disease
    Natter’s Notes summer. By mid-summer, Pear Trellis Rust, a tiny black dots (pycnia) appear in the center of the new disease leaf spots.” [Fig 3] By late Jean R. Natter summer, brown, blister-like swellings form on the lower Recently, Pear Trellis Rust leaf surface just beneath (Gymnosporangium the leaf spots. This is sabinae) became the followed by the newest contributor to this development of acorn- hodge-podge-let’s-try- shaped structures (aecia) everything year. During with open, trellis-like sides 2016, the first case of pear Fig 1: Pear trellis rust (Gymnosporangium sabinae) on the top that give this disease its trellis rust was reported in leaf surface of edible pear tree; Multnomah County, OR. (Client common name. (Fig 4) the northern section of the image; 2017-09) Aeciospores produced within Willamette Valley, that on a Bartlett pear growing in the aecia are wind-blown to susceptible juniper Milwaukie, Clackamas County. (See “Pear Trellis hosts where they can cause infections on young Rust: First Report in Oregon” Metro MG Newsletter, shoots. These spores are released from late summer January 2016; until leaf drop.” (“Pear Trellis Rust, http://extension.oregonstate.edu/mg/metro/sites/d Gymnosporangium sabinae” efault/files/dec_2016_mg_newsletter_12116.pdf. (http://www.ladybug.uconn.edu/FactSheets/pear- Then, in mid-September 2017, an inquiry about a trellis-rust_6_2329861430.pdf) pear leaf problem in Multnomah County was submitted to Ask an Expert. [Fig 1; Fig 2] Yes, it’s Signs on affected alternate host junipers are difficult another fruiting pear tree infected with trellis rust. It to detect.
    [Show full text]
  • Comprehensive Assessment of Organic Apple Production in Vermont: Experience from Two Orchard Systems, 2006-2013 Terence L
    University of Vermont ScholarWorks @ UVM Graduate College Dissertations and Theses Dissertations and Theses 2015 Comprehensive Assessment of Organic Apple Production in Vermont: Experience from Two Orchard Systems, 2006-2013 Terence L. Bradshaw University of Vermont Follow this and additional works at: https://scholarworks.uvm.edu/graddis Part of the Agricultural Economics Commons, and the Horticulture Commons Recommended Citation Bradshaw, Terence L., "Comprehensive Assessment of Organic Apple Production in Vermont: Experience from Two Orchard Systems, 2006-2013" (2015). Graduate College Dissertations and Theses. 327. https://scholarworks.uvm.edu/graddis/327 This Dissertation is brought to you for free and open access by the Dissertations and Theses at ScholarWorks @ UVM. It has been accepted for inclusion in Graduate College Dissertations and Theses by an authorized administrator of ScholarWorks @ UVM. For more information, please contact [email protected]. COMPREHENSIVE ASSESSMENT OF ORGANIC APPLE PRODUCTION IN VERMONT: EXPERIENCE FROM TWO ORCHARD SYSTEMS, 2006-2013 A Dissertation Presented by Terence L. Bradshaw to The Faculty of the Graduate College of The University of Vermont In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Specializing in Plant and Soil Science May, 2015 Defense Date: March 25, 2014 Dissertation Examination Committee: Josef H. Gorres, Ph. D., Advisor Robert L. Parsons, Ph.D., Chairperson Lorraine P. Berkett, Ph.D. Sidney C. Bosworth, Ph.D. Cynthia J. Forehand, Ph.D., Dean of the Graduate College ABSTRACT Despite substantial consumer demand and willingness to pay premium prices for organically grown fruit, apple growers in Vermont and other New England states have been slow to adopt certified organic practices.
    [Show full text]
  • Apples: Organic Production Guide
    A project of the National Center for Appropriate Technology 1-800-346-9140 • www.attra.ncat.org Apples: Organic Production Guide By Tammy Hinman This publication provides information on organic apple production from recent research and producer and Guy Ames, NCAT experience. Many aspects of apple production are the same whether the grower uses low-spray, organic, Agriculture Specialists or conventional management. Accordingly, this publication focuses on the aspects that differ from Published nonorganic practices—primarily pest and disease control, marketing, and economics. (Information on March 2011 organic weed control and fertility management in orchards is presented in a separate ATTRA publica- © NCAT tion, Tree Fruits: Organic Production Overview.) This publication introduces the major apple insect pests IP020 and diseases and the most effective organic management methods. It also includes farmer profiles of working orchards and a section dealing with economic and marketing considerations. There is an exten- sive list of resources for information and supplies and an appendix on disease-resistant apple varieties. Contents Introduction ......................1 Geographical Factors Affecting Disease and Pest Management ...........3 Insect and Mite Pests .....3 Insect IPM in Apples - Kaolin Clay ........6 Diseases ........................... 14 Mammal and Bird Pests .........................20 Thinning ..........................20 Weed and Orchard Floor Management ......20 Economics and Marketing ........................22 Conclusion
    [Show full text]
  • Introduction to Neotropical Entomology and Phytopathology - A
    TROPICAL BIOLOGY AND CONSERVATION MANAGEMENT – Vol. VI - Introduction to Neotropical Entomology and Phytopathology - A. Bonet and G. Carrión INTRODUCTION TO NEOTROPICAL ENTOMOLOGY AND PHYTOPATHOLOGY A. Bonet Department of Entomology, Instituto de Ecología A.C., Mexico G. Carrión Department of Biodiversity and Systematic, Instituto de Ecología A.C., Mexico Keywords: Biodiversity loss, biological control, evolution, hotspot regions, insect biodiversity, insect pests, multitrophic interactions, parasite-host relationship, pathogens, pollination, rust fungi Contents 1. Introduction 2. History 2.1. Phytopathology 2.1.1. Evolution of the Parasite-Host Relationship 2.1.2. The Evolution of Phytopathogenic Fungi and Their Host Plants 2.1.3. Flor’s Gene-For-Gene Theory 2.1.4. Pathogenetic Mechanisms in Plant Parasitic Fungi and Hyperparasites 2.2. Entomology 2.2.1. Entomology in Asia and the Middle East 2.2.2. Entomology in Ancient Greece and Rome 2.2.3. New World Prehispanic Cultures 3. Insect evolution 4. Biodiversity 4.1. Biodiversity Loss and Insect Conservation 5. Ecosystem services and the use of biodiversity 5.1. Pollination in Tropical Ecosystems 5.2. Biological Control of Fungi and Insects 6. The future of Entomology and phytopathology 7. Entomology and phytopathology section’s content 8. ConclusionUNESCO – EOLSS Acknowledgements Glossary Bibliography Biographical SketchesSAMPLE CHAPTERS Summary Insects are among the most abundant and diverse organisms in terrestrial ecosystems, making up more than half of the earth’s biodiversity. To date, 1.5 million species of organisms have been recorded, although around 85% of potential species (some 10 million) have not yet been identified. In the case of the Neotropics, although insects are clearly a vital element, there are many families of organisms and regions that are yet to be well researched.
    [Show full text]
  • Survey of Apple Clones in the United States
    Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. 5 ARS 34-37-1 May 1963 A Survey of Apple Clones in the United States u. S. DFPT. OF AGRffini r U>2 4 L964 Agricultural Research Service U.S. DEPARTMENT OF AGRICULTURE PREFACE This publication reports on surveys of the deciduous fruit and nut clones being maintained at the Federal and State experiment stations in the United States. It will b- published in three c parts: I. Apples, II. Stone Fruit. , UI, Pears, Nuts, and Other Fruits. This survey was conducted at the request of the National Coor- dinating Committee on New Crops. Its purpose is to obtain an indication of the volume of material that would be involved in establishing clonal germ plasm repositories for the use of fruit breeders throughout the country. ACKNOWLEDGMENT Gratitude is expressed for the assistance of H. F. Winters of the New Crops Research Branch, Crops Research Division, Agricultural Research Service, under whose direction the questionnaire was designed and initial distribution made. The author also acknowledges the work of D. D. Dolan, W. R. Langford, W. H. Skrdla, and L. A. Mullen, coordinators of the New Crops Regional Cooperative Program, through whom the data used in this survey were obtained from the State experiment stations. Finally, it is recognized that much extracurricular work was expended by the various experiment stations in completing the questionnaires. : CONTENTS Introduction 1 Germany 298 Key to reporting stations. „ . 4 Soviet Union . 302 Abbreviations used in descriptions .... 6 Sweden . 303 Sports United States selections 304 Baldwin.
    [Show full text]
  • Pear Trellis Rust
    Dr. Yonghao Li Department of Plant Pathology and Ecology The Connecticut Agricultural Experiment Station 123 Huntington Street, P. O. Box 1106 New Haven, CT 06504 Phone: (203) 974-8601 Fax: (203) 974-8502 Founded in 1875 Email: [email protected] Putting science to work for society Website: www.ct.gov/caes PEAR TRELLIS RUST Pear trellis rust (European pear rust) is one premature defoliation, significant diebacks, of most devastating diseases on fruit and and reduced tree vigour (Figure 1). ornamental pear trees in Europe. In the United States, since the disease was first SYMPTOMS AND DIAGNOSTICS reported in the Bellingham, WA in 1997, it The disease affects pear and juniper plants, has moved from the west coast to east coast. which is the alternate host of the fungal In Connecticut, pear trellis rust was first pathogen Gymnosporangium sabinae. On reported in 2012. Although the disease is pear trees, the disease mainly damages considered cosmetic on pear trees, heavy and leaves although twigs and fruit can also be repeated infections due to wet spring infected. The initial symptom appears as weather conditions may result in severe yellow spots on the upper side of young leaves in the spring. Lesions become reddish orange in color and expand up to 3/4 inch in diameter (Figure 2). By mid summer, small black dots (spermagonia) form in the center of the spot on the upper side of leaves. And then, light brown, Figure 1. Browning of leaves and early Figure 2. Reddish-brown lesions on the defoliation of heavily infected pear trees in upper- (left) and lower-side (right) of the early summer leaf acorn-shaped structures (aecia) form on the differences in susceptibility between under side of the leaf directly below the varieties.
    [Show full text]
  • Master Thesis
    Swedish University of Agricultural Sciences Faculty of Natural Resources and Agricultural Sciences Department of Forest Mycology and Plant Pathology Uppsala 2011 Taxonomic and phylogenetic study of rust fungi forming aecia on Berberis spp. in Sweden Iuliia Kyiashchenko Master‟ thesis, 30 hec Ecology Master‟s programme SLU, Swedish University of Agricultural Sciences Faculty of Natural Resources and Agricultural Sciences Department of Forest Mycology and Plant Pathology Iuliia Kyiashchenko Taxonomic and phylogenetic study of rust fungi forming aecia on Berberis spp. in Sweden Uppsala 2011 Supervisors: Prof. Jonathan Yuen, Dept. of Forest Mycology and Plant Pathology Anna Berlin, Dept. of Forest Mycology and Plant Pathology Examiner: Anders Dahlberg, Dept. of Forest Mycology and Plant Pathology Credits: 30 hp Level: E Subject: Biology Course title: Independent project in Biology Course code: EX0565 Online publication: http://stud.epsilon.slu.se Key words: rust fungi, aecia, aeciospores, morphology, barberry, DNA sequence analysis, phylogenetic analysis Front-page picture: Barberry bush infected by Puccinia spp., outside Trosa, Sweden. Photo: Anna Berlin 2 3 Content 1 Introduction…………………………………………………………………………. 6 1.1 Life cycle…………………………………………………………………………….. 7 1.2 Hyphae and haustoria………………………………………………………………... 9 1.3 Rust taxonomy……………………………………………………………………….. 10 1.3.1 Formae specialis………………………………………………………………. 10 1.4 Economic importance………………………………………………………………... 10 2 Materials and methods……………………………………………………………... 13 2.1 Rust and barberry
    [Show full text]
  • Apple Scab (Venturia Inaequalis) and Pests in Organic Orchards
    Apple Scab (Venturia inaequalis) and Pests in Organic Orchards Boel Sandskär Department of Crop Science, Alnarp Doctoral Thesis Swedish University of Agricultural Sciences Alnarp 2003 2 Abstract Sandskär, B. Apple Scab (Venturia inaequalis) and Pests in Organic Orchards Doctoral Dissertation ISSN 1401-6249, ISBN 91-576-6416-1 Domestication of apples goes back several thousand years in time and archaeological findings of dried apples from Östergötland in Sweden have been dated to ca 2 500 B.C. Worldwide, apples are considered an attractive and healthy fruit to eat. Organic production of apples is increasing abroad but is still at very low levels in Sweden. This study deals with major disease and pest problems in organic growing of apples. It concentrates on the most severe disease, the apple scab (Venturia inaequalis). Resistance to apple scab was evaluated during three years in over 450 old and new apple cultivars at Alnarp and Balsgård in southern Sweden. There were significant differences between the cultivars and years. About ten per cent of the cultivars had a high level of resistance against apple scab. The correlation between foliar and fruit scab was stronger when the scab infection pressure was high (1998-1999), compared to when it was low (2000). Polygenic resistance is a desirable trait since such resistance is more difficult to overcome by the pathogen. A common denominator for polygenic resistance among the cultivars assessed was 'Worcester Pearmain'. The leaf infection of apple scab was compared at three locations: Alnarp, Kivik and Rånna (Skövde) in an observation trial for 22 new apple cultivars. The ranking of the cultivars was similar at the three locations.
    [Show full text]