DOCSLIB.ORG

Common Diseases

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Common Diseases The Morton Arboretum’s Tree Care Quick Facts COMMON DISEASES Not all diseases are destructive to trees. Nondestructive diseases are often called nuisance diseases, as they typically only impact the tree aesthetically. Below are some common examples. Please contact The Morton Arboretum’s Plant Clinic (mortonarb.org/plantadvice) before considering treatment. Apple Scab Sycamore Anthracnose Apple scab is caused by a fungus in spring Anthracnose is caused by several species Apple Scab as new leaf growth emerges. It can mostly of fungi whose spores infect newly be observed on leaves, blossoms, and fruit. emerging leaves. The disease can become Symptoms look like small velvety brown to severe when cool, wet spring weather olive green spots that enlarge and darken persists. The trees most likely to be to become somewhat circular. Severely affected are quite common, such as ash, infected leaves and fruit fall prematurely. elm, hickory, maple, oak, sycamore, and The fungus overwinters on fallen leaves. It walnut. Most anthracnose symptoms are seen on the lower two-thirds of is important to rake up leaves and dispose the tree's canopy, while the upper third of them off the property. looks unaffected. Sycamore anthracnose, Cedar-Apple Rust unlike other anthracnose diseases, can Cedar-apple rust is caused by a fungus also infect twigs and branches and kill Cedar-Apple Rust that needs two hosts: a juniper, such as buds, resulting in clusters of growth called eastern red-cedar, and, a deciduous host witch's brooms. In bad years, sycamore anthracnose can cause trees to lose all such as crabapple, hawthorn, or quince. their leaves by June. The trees grow new On the apple tree, symptoms include leaves in early July, but the production of leaf spots on the upper and lower side new leaves can weaken them. Remove of the leaves and infections on fruits and diseased leaves as soon as they drop off. branches. Symptoms of infection on the junipers are noticeable tan-brown galls Phomopsis Blight that produce bright orange tendrils in the Phomopsis tip blight is a fungal disease spring. Repeated infestations can destroy that mostly affects evergreens, including the ornamental value of healthy trees. junipers, arborvitae, and some pines. Sycamore Anthracnose Symptoms are first noticeable in spring when new growth changes from light yellow green to red brown to ash gray as it dies. Small stems are usually girdled by these lesions, causing tip death. The blight is spread by splashing rain, wind, insects, or mechanical means such as pruners that have not been disinfected. Prune out diseased branch tips during dry summer The MortonArboretum T_Indigo ©2014 olland 80# weather and discard. Phomopsis Blight 300_07/14_ACE_R THE MORTON ARBORETUM | 4100 Illinois Route 53 Lisle, IL 60532 | mortonarb.org/plantadvice The Morton Arboretum’s Tree Care Quick Facts NONTHREATENING INSECTS Some insects will not typically cause trees to die, but tend to greatly affect tree aesthetics. Below are common, nonthreatening insects found in the Chicago region. Before considering treatment, please contact The Morton Arboretum’s Plant Clinic (mortonarb.org/ plantadvice) for more information and complete descriptions of these insects. Scales Scales the time. Its damage is mostly a cosmetic There are many species of scale insects problem. The tentlike structures from both that feed on a wide range of host plants. caterpillars can be removed by hand. Scale insects generally feed on plant sap and some species produce a sticky Gall-forming Insects substance often called honeydew that Galls are abnormal growths that occur drips onto branches and foliage below. on leaves, twigs, roots, or flowers of many Heavy infestations can cause branch plants. While most galls are caused by dieback. Different scale insects require irritation and/or stimulation of plant cells different treatments. due to feeding or egg-laying by insects Japanese Beetles such as aphids, midges, wasps, or mites, Japanese Beetles some are the result of infections by Common in the Chicago region, Japanese bacteria, fungi, or nematodes. Most galls beetles are 1/2 inch long, shiny, and are nonthreatening, causing only unsightly metallic green with coppery-brown wing distortion on affected plant tissue, though covers. As grubs, Japanese beetle larvae stem galls can do damage. overwinter in the soil and can damage lawns by feeding on grass roots. Adult Pine Sawflies Caterpillars beetles emerge from the soil in late June There are more than 100 species of and feed until mid-August on leaves of sawflies known in the United States. 300 different plant species. Feeding can The pine sawfly gets its name from the skeletonize leaves so only the leaf veins sawlike apparatus at the tip of the adult's remain. Several years of high beetle abdomen used for egg laying. Pine sawfly populations can drastically reduce the larvae feed in groups on white pine, mugo, vigor of affected trees and plants. and other pines. Due to their vigorous and Caterpillars lengthy feeding periods, large populations of sawflies can cause significant defoliation Two common pests of deciduous trees to host plants. Control requires constant Gall-forming Insects are the Eastern tent caterpillar (active vigilance and immediate action when in spring) and the fall webworm (active populations are detected. Remove the in summer and fall), whose gauzy larvae by hand or use a forceful spray tents deface trees on roadsides, home landscapes, and orchards. Tent caterpillars of water to dislodge them. feed on leaves of ornamental trees during the day and return to their nests at night. olland 80# T_Indigo ©2014 The MortonArboretum T_Indigo ©2014 olland 80# They can defoliate a tree, but the tree may send out new leaves later in the season. Fall webworm stays in the nest all Pine Sawflies 300_07/14_ACE_R THE MORTON ARBORETUM | 4100 Illinois Route 53 Lisle, IL 60532 | mortonarb.org/plantadvice The Morton Arboretum’s Tree Care Quick Facts THREATENING INSECTS Below are the most common destructive insects in the Chicago region. If untreated, they can kill trees, though sometimes the insects are so harmful that treatment is futile. Before considering treatment, please contact The Morton Arboretum’s Plant Clinic (mortonarb.org/plantadvice) for more information and complete descriptions of these insects. Emerald Ash Borer Emerald Ash Borer Adults are nocturnal gray-brown moths The emerald ash borer (EAB) is a major and are rarely seen. invasive species. Adults are metallic emerald green, bullet-shaped beetles Bronze Birch Borer that are smaller than a penny. Established Similar to emerald ash borer in shape and across most of the United States, EAB size, this metallic bronze beetle affects causes significant mortality to native ash stressed birches of several species. In the Two-Lined Chestnut Borer trees (Fraxinus) during its larval stage. larval stage, the borer tunnels beneath the The larvae feed on water-conducting bark, cutting off the supply of water and tree tissue just under the bark, creating nutrients. Some birch species are resistant distinctive serpentine tunnels. As the to bronze birch borer. larvae rapidly multiply, these tunnels girdle a tree in one to three years. Chemical National Invasive Species of Critical Concern. injections can be used to protect trees from EAB larvae if applied before Gypsy Moth Zimmerman Pine Moth Gypsy moth is a major invasive species. Its significant damage is done. caterpillars feed on more than 450 kinds Two-Lined Chestnut Borer of trees but favor oaks. Found throughout Two-lined chestnut borer attacks many northeastern Illinois, the caterpillars hatch types of oaks. Trees that are stressed, in spring from buff-colored egg masses injured, or weakened are most susceptible. and begin feeding in groups. The adult The adult beetle is slender, greenish-black, male moth is brown and the female is and bullet-shaped with two yellow stripes white with black markings. To help slow Bronze Birch Borer along its back. The larvae feed under the the spread of gypsy moth, check for for bark and destroy the water-conducting egg masses on outdoor surfaces during tissues, causing branch dieback and the winter and remove them. eventually killing the tree. Prevention is the best defense. Healthy trees are Asian Longhorned Beetle less susceptible. One of the most serious invasive pests, the Asian longhorned beetle (ALB) is Zimmerman Pine Moth black with several white spots on its Gypsy Moth The Zimmerman pine moth generally back. It feeds on more than 14 tree attacks Douglas-fir and Scots, Austrian species, especially maples. The beetle is and red pines. The pine moth’s larval stage most destructive in its larval stage. The does the most damage. The larvae tunnel larvae tunnel not only in the water- and under the bark, girdling the trunk or large nutrient-carrying tissues of a tree but also branches and cutting off the supply of in the inner heartwood, undermining the water and nutrients. Masses of sap are tree’s structure. Although eradicated in apparent on the affected areas of the the Chicago region, ALB persists in large Asian Longhorned Beetle tree, usually near branch whorls. sections of the eastern United States. THE MORTON ARBORETUM | 4100 Illinois Route 53 Lisle, IL 60532 | mortonarb.org/plantadvice The Morton Arboretum’s Tree Care Quick Facts THREATENING DISEASES Below are the most common destructive tree diseases in the Chicago region. If untreated, they can kill trees, though sometimes the diseases are so harmful that treatment may be futile. Before considering treatment, please contact The Morton Arboretum’s Plant Clinic (mortonarb.org/plantadvice) for more information and complete descriptions of these diseases. Dutch Elm Disease (DED) Cankers Caused by a fungus, this disease can spread Cankers vary in size and shape. They Dutch Elm Disease readily in elm-rich areas due to the fungus' appear as sunken or discolored lesions ability to move not only with the help of on the bark of trunks and branches or elm bark beetles, but also through grafted as injured areas on smaller twigs.
Load more

Recommended publications
  • Diseases of Trees in the Great Plains
    United States Department of Agriculture Diseases of Trees in the Great Plains Forest Rocky Mountain General Technical Service Research Station Report RMRS-GTR-335 November 2016 Bergdahl, Aaron D.; Hill, Alison, tech. coords. 2016. Diseases of trees in the Great Plains. Gen. Tech. Rep. RMRS-GTR-335. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 229 p. Abstract Hosts, distribution, symptoms and signs, disease cycle, and management strategies are described for 84 hardwood and 32 conifer diseases in 56 chapters. Color illustrations are provided to aid in accurate diagnosis. A glossary of technical terms and indexes to hosts and pathogens also are included. Keywords: Tree diseases, forest pathology, Great Plains, forest and tree health, windbreaks. Cover photos by: James A. Walla (top left), Laurie J. Stepanek (top right), David Leatherman (middle left), Aaron D. Bergdahl (middle right), James T. Blodgett (bottom left) and Laurie J. Stepanek (bottom right). To learn more about RMRS publications or search our online titles: www.fs.fed.us/rm/publications www.treesearch.fs.fed.us/ Background This technical report provides a guide to assist arborists, landowners, woody plant pest management specialists, foresters, and plant pathologists in the diagnosis and control of tree diseases encountered in the Great Plains. It contains 56 chapters on tree diseases prepared by 27 authors, and emphasizes disease situations as observed in the 10 states of the Great Plains: Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, and Wyoming. The need for an updated tree disease guide for the Great Plains has been recog- nized for some time and an account of the history of this publication is provided here.
    [Show full text]
  • Managing Fire Blight by Choosing Decreased Host Susceptibility Levels and Rootstock Traits , 2020 , January 15 January
    Managing Fire Blight by Choosing Decreased Host Susceptibility Levels and Rootstock Traits , 2020 , January 15 January Awais Khan Plant Pathology and Plant-microbe Biology, SIPS, Cornell University, Geneva, NY F ire blight bacterial infection of apple cells Khan et al. 2013 Host resistance and fire blight management in apple orchards Host resistance is considered most sustainable option for disease management due to Easy to deploy/implement in the orchards Low input and cost-effective Environment friendly No choice to the growers--most of the new and old cultivars are highly susceptible Apple breeding to develop resistant cultivars Domestication history of the cultivated apple 45-50 Malus species-----Malus sieversii—Gene flow Malus baccata Diameter: 1 cm Malus sieversii Malus baccata Diameter: up to 8 cm Malus orientalis Diameter: 2-4 cm Malus sylvestris Diameter: 1-3 cm Duan et al. 2017 Known sources of major/moderate resistance to fire blight to breed resistant cultivars Source Resistance level Malus Robusta 5 80% Malus Fusca 66% Malus Arnoldiana, Evereste, Malus floribunda 821 35-55% Fiesta, Enterprise 34-46% • Fruit quality is the main driver for success of an apple cultivar • Due to long juvenility of apples, it can take 20-25 years to breed resistance from wild crab apples Genetic disease resistance in world’s largest collection of apples Evaluation of fire blight resistance of accessions from US national apple collection o Grafted 5 replications: acquired bud-wood and rootstocks o Inoculated with Ea273 Erwinia amylovora strain
    [Show full text]
  • Tree Diseases
    Tree Diseases In North Texas home owners cherish their trees for their beauty and for their shade protection from summer’s sun. Unfortunately, trees can experience problems that affect their attractive appearance and may even lead to death. Trees are vulnerable to environmental stress, infectious diseases, insects and human-caused damage. Correctly diagnosing the cause of a tree’s problem is the most important step in successful treatment. To determine if your tree has a disease, examine the whole tree not just the area showing symptoms suggests Iowa State University Extension Service (Diagnosing Tree Problems). Check leaves for holes or ragged edges, discoloration or deformities Look at the tree’s trunk for damage to the bark such as cracks or splits Consider previous activity that may have impacted the tree’s root system such as planting shrubs nearby or construction of a sidewalk or adding hardscape like a deck or patio The following diseases occur in Denton County. This is not all-inclusive, but Master Gardeners have seen all of these (with the exception of oak wilt). If you need help diagnosing a tree problem, send a picture of the entire tree and close-ups of the problem area(s) to the help desk at [email protected]. If it is a new tree, include a picture of the bottom of the trunk where it meets the soil. Include such information as: Age of the tree When the problem was noticed Sudden or gradual onset Presence of insects Anything else you believe is relevant Anthracnose This fungus is usually on lower branches, following a cool, wet, spring.
    [Show full text]
  • Fire Blight of Apple and Pear
    WASHINGTON STATE UNIVERSITY EXTENSION Fire Blight of Apple and Pear Updated by Tianna DuPont, WSU Extension, February 2019. Original publication by Tim Smith, Washington State University Tree Fruit Extension Specialist Emeritus; David Granatstein, Washington State University; Ken Johnson, Professor of Plant Pathology Oregon State University. Overview Fire blight is an important disease affecting pear and apple. Infections commonly occur during bloom or on late blooms during the three weeks following petal fall. Increased acreage of highly susceptible apple varieties on highly susceptible rootstocks has increased the danger that infected blocks will suffer significant damage. In Washington there have been minor outbreaks annually since 1991 and serious damage in about 5-10 percent of orchards in 1993, 1997, 1998, 2005, Figure 2 Bloom symptoms 12 days after infection. Photo T. DuPont, WSU. 2009, 2012, 2015, 2016, 2017 and 2018. Shoot symptoms. Tips of shoots may wilt rapidly to form a Casual Organism “shepherd’s crook.” Leaves on diseased shoots often show blackening along the midrib and veins before becoming fully Fire blight is caused by Erwinia amylovora, a gram-negative, necrotic, and cling firmly to the host after death (a key rod-shaped bacterium. The bacterium grows by splitting its diagnostic feature.) Numerous diseased shoots give a tree a cells and this rate of division is regulated by temperature. Cell burnt, blighted appearance, hence the disease name. division is minimal below 50 F, and relatively slow at air temperatures between 50 to 70 F. At air temperatures above 70 F, the rate of cell division increases rapidly and is fastest at 80 F.
    [Show full text]
  • Cherry Fire Blight
    ALABAMA A&M AND AUBURN UNIVERSITIES Fire Blight on Fruit Trees and Woody Ornamentals ANR-542 ire blight, caused by the bac- Fterium Erwinia amylovora, is a common and destructive dis- ease of pear, apple, quince, hawthorn, firethorn, cotoneaster, and mountain ash. Many other members of the rose plant family as well as several stone fruits are also susceptible to this disease (Table 1). The host range of the Spur blight on crabapple fire blight pathogen includes cv ‘Mary Potter’. nearly 130 plant species in 40 genera. Badly diseased trees and symptoms are often referred to shrubs are usually disfigured and as blossom blight. The blossom may even be killed by fire blight phase of fire blight affects blight. different host plants to different degrees. Fruit may be infected Symptoms by the bacterium directly through the skin or through the The term fire blight describes stem. Immature fruit are initially Severe fire blight on crabapple the blackened, burned appear- water-soaked, turning brownish- cv ‘Red Jade’. ance of damaged flowers, twigs, black and becoming mummified and foliage. Symptoms appear in as the disease progresses. These Shortly after the blossoms early spring. Blossoms first be- mummies often cling to the trees die, leaves on the same spur or come water-soaked, then wilt, for several months. shoot turn brown on apple and and finally turn brown. These most other hosts or black on Table 1. Plant Genera That Include Fire Blight Susceptible Cultivars. Common Name Scientific Name Common Name Scientific Name Apple, Crabapple Malus Jetbead Rhodotypos
    [Show full text]
  • Fireblight–An Emerging Problem for Blackberry Growers in the Mid-South
    North American Bramble Growers Research Foundation 2016 Report Fire Blight: An Emerging Problem for Blackberry Growers in the Mid-South Principal Investigator: Burt Bluhm University of Arkansas Department of Plant Pathology 206 Rosen Center Voice: (479) 575-2677 Fax: (479) 575-7601 Julia Stover University of Arkansas Department of Plant Pathology 211 Rosen Center A poster with many of these initial findings was presented at the North American Berry Conference in Grand Rapids, MI in December 2016 Background and Initial Rationale: Fire blight, caused by the bacterial pathogen Erwinia amylovora, infects all members of the family Rosaceae and is considered to be the single most devastating bacterial disease of apple. Erwinia amylovora was first isolated from blighted blackberry plants in Illinois in 1976, from both mummified fruit and blighted canes (Ries and Otterbacher, 1977). These symptoms had been sporadically reported previously in both blackberry and raspberry, but the causal agent had never been identified. Since this first report, the disease has been found throughout the blackberry growing regions of the United States, but is generally not considered to be a pathogen of major concern (Smith, 2014; Clark, personal communication). However, with the advent of primocane fruiting plants, a significant increase in disease incidence has been witnessed in Arkansas (Garcia, personal communication) and fruit loss of up to 65% has been reported in Illinois (Schilder, 2007). Fire blight is a disease that is very environmentally dependent, and warm, wet weather at flowering is most conducive to serious disease development. The Arkansas growing conditions are ideal for disease development, and the shift in production season with primocane fruiting moves flowering time to a time of year with temperatures cool enough for bacterial growth (Smith, 2014).
    [Show full text]
  • Home Orchards Disease and Insect Control Recommendations
    INTEGRATED PEST MANAGEMENT Home Orchards Disease and Insect Control Recommendations Apple and Pear Apple and pear trees are subject to serious damage from pests. As a result, a preventive spray program is needed. The following practices will improve the effectiveness of the pesticides and may lessen the need for sprays. ■ Plant disease-resistant varieties. This method of disease control is especially important for fire blight, where chemical control options are limited. Varieties resistant to cedar-apple rust, scab, and powdery mildew also are available and will potentially reduce the need for sprays. ■ Rake and destroy leaves in the fall if apple scab or pear leaf spot are problems. The fungi that cause these diseases can survive through the winter in ■ Prune out and destroy all dead or diseased shoots infected leaves. and limbs during the dormant season. This helps to reduce fire blight, fruit rots, and certain leaf spots, ■ Remove diseased galls from cedar trees. Spores as the organisms that cause these diseases can from these cedars can infect apples, causing cedar- survive through the winter in the wood. Removing apple rust. Elimination of the source of spores (cedar mummified (dark, shriveled, dry) fruit helps to prevent trees) is effective but not always possible. Where the overwintering of the fruit rot organisms. cedars are part of an established landscape, remove and destroy all galls caused by the rust fungus on ■ Prune out fire blight–affected shoots and blossom cedars in the late fall. Inspect the cedars again in clusters during the growing season only as symptoms the early spring during or just after a rain when the appear.
    [Show full text]
  • Fire Blight of Pears and Apples,” Utah Plant Disease Control No
    UtahUtah Pest Factsheet Published by Utah State University Extension and Utah Plant Pest Diagnostic Laboratory PLP-009 June 2008 Adapted from “Fire Blight of Pears and Apples,” Utah Plant Disease Control No. 27, Revised 2000. Fire Blight Kent Evans, Extension Plant Pathology Specialist been found in all pear and apple-producing areas Erin Frank, USU Plant Disease Diagnostician in the United States, as well as in New Zealand and Taun Beddes, Cache County Extension Agent Europe. Erwinia amylovora has the ability to infect many Mike Pace, Box Elder County Extension Agent ornamental plants of the rose family, but is particularly Maggie Shao, Salt Lake County Extension Agent important on pear and apple. It not only destroys the Alicia Moulton, Wasatch County Extension Agent current season’s crop, but may damage the structure of the tree and reduce subsequent production. Highly What You Should Know susceptible trees may be killed in a single season. Fire blight is a bacterial disease of rosaceous plants. Economically, it is most serious on pears and apples. Symptoms The bacterium that causes fire blight, Erwinia amylovora, can be spread by insects, contaminated pruning or graft- Fire blight symptoms are easily recognized by the ing tools, infected grafts, and any manner that carries scorched appearance of leaves, blossoms, and young the bacterial pathogen from an infected plant to one that terminal shoots. Initial infection causes wilt; infected tis- is not, including wind and rain-splash. Pear and apple sue and tissue outward of infections turns black on pear are most susceptible at flowering, but actively growing and brown on apple.
    [Show full text]
  • Crataegus (Hawthorn)
    nysipm.cornell.edu 2019 Search for this title at the NYSIPM Publications collection: ecommons.cornell.edu/handle/1813/41246 Disease and Insect Resistant Ornamental Plants Mary Thurn, Elizabeth Lamb, and Brian Eshenaur New York State Integrated Pest Management Program, Cornell University CRATAEGUS Hawthorn pixabay.com Crataegus is a large genus of shrubs and small trees in the rose family commonly known as hawthorn. This popular ornamental has showy pink or white flowers in spring and colorful berry-like fruit. Some species also have long thorns that provide protection for wildlife but may be a hazard in the landscape–thornless cultivars are available. Like other rosaceous plants, hawthorns are sus- ceptible to a number of diseases including fire blight, scab, leaf spot and several types of rust. Insect pests include lace bugs and leaf miners. DISEASES Cedar Rust diseases on hawthorn, which include hawthorn rust and quince rust, are caused by sev- eral fungi in the genus Gymnosporangium that spend part of their life cycle on Eastern red cedar (Juni- perus virginiana) and other susceptible junipers, and another part of their life cycle on plants in the rose family, especially Malus and Crataegus. Since two hosts are required for these fungi to complete their life cycle, one way to reduce disease problems is to avoid planting alternate hosts near each other. Hawthorn Rust, caused by Gymnosporangium globosum, is a significant concern for Crataegus spp. in the Northeast (7). Hawthorns are the main broadleaved host for this rust, and yellow-orange leaf spots are the most common symptom. (8). With severe infections, foliage may turn bright yellow and drop prematurely (15).
    [Show full text]
  • Performance of New Fire Blight Resistant Pears
    Bill Shane - New Fire Blight Resistant Pears Michigan State University Performance of New Fire Blight Resistant Pears Bill Shane Michigan State University SW Michigan Research and Extension Center Benton Harbor, MI Bill Shane - New Fire Blight Resistant Pears Michigan State University Michigan pear industry Estimated 800 acres Bartlett 83% Bosc 6% Clapp 1% D’Anjou 1% Other 9% Uses of pears . Fresh for local, roadside, & farmers market . Home canning uses . Processing for babyfood. Limited use in wine and brandy Bill Shane - New Fire Blight Resistant Pears Michigan State University Processing qualities for puree taste (pear flavor): strong pear brix/ titratable acidity puree color texture: amount of stone cells consistency: watery to very thick Bill Shane - New Fire Blight Resistant Pears Michigan State University Fire blight is the most important problem of Michigan pear industry Estimated 800 acres Bartlett 83% Bosc 6% Clapp 1% D’Anjou 1% Other 9% Bartlett Bosc Bill Shane - New Fire Blight Resistant Pears Michigan State University European Pear Varieties with good to excellent fire blight resistance Variety Harvest Variety Harvest Harrow Delight -14 Seckel +8 Moonglow -12 Blake’s Pride +10 Harrow Gold -10 Shenandoah +10 Sunrise -12 Harrow Sweet +14 Harvest Queen -7 Potomac +18 Warren 0 Harovin Sundown +21 Harrow Crisp +3 Comice +30 Gem +5 Kieffer +30 Magness +7 Harvest = days before (-) or after (+) Bartlett Bill Shane - New Fire Blight Resistant Pears Michigan State University Sources of new European pear varieties with fire blight resistance
    [Show full text]
  • Fire Blight Mary W
    ARIZONA COOPERATIVE E TENSION AZ1030 Revised 01/11 plant disease management Horticultural Crops Fire Blight Mary W. Olsen Figure 2. Brown flecking of the vascular tissue is commonly used for diagno- sis of Verticillium wilt but may not always be present. Figure 1. Fireblight symptoms in loquat. Figure 2. Wilting and bending of infected shoots. Pathogen Bacterium, Erwinia amylovora Host Apple, pear, pyracantha, loquat, quince and other plants At a Glance in the rose family. • Fire blight is a bacterial disease that affects only plants in the rose family such as apple, pear, loquat Symptoms/signs and pyracantha; roses are not affected. If flowers are infected in the spring during bloom, blossom clusters wilt and shrivel, turn dark brown or black and die • Dieback of twigs and branches, as well as shriveling within a few days (Figure 1). During spring and summer of flowers, occurs in warm, moist weather; affected months, infected shoots and twigs have reddish-brown tissues turn very dark and twigs are crook shaped. streaking that turns brown in apple and brown to black • Prevent disease by planting tolerant varieties; on in pear. Extensive branch killing is more common in pear susceptible varieties, use an antibiotic or copper than in apple. Infected shoots often bend at the tips and spray to prevent bloom infection. are referred to as a “shepherd’s crook” in describing disease symptoms (Figure 2). Masses of bacteria may ooze from • Control by pruning infected tissue well away from infected tissue as a sticky amber or brown droplets. Cankers infection site using a 20% bleach dip for tools in infected branches and trunks have a water-soaked between cuts.
    [Show full text]
  • Fire Blight Fact Sheet
    Fire Blight Fact Sheet A bacterial disease of apple, crab apple and pear trees Fire blight is a destructive bacterial disease of apples, crab apples and pear trees, as well as other related plants such as cotoneaster shrubs and mountain ash. Warm rainy springs and open wounds allow rapid spread of the disease. Fire blight is most severe before and during bloom when spring temperatures are warmer than average. Fire blight can destroy the blossoms, fruit, and stems of the plant, and even kill the plant. Treatment options are limited for infected trees Fire blight is difficult to treat effectively, because the bacteria live in the wood of the tree and are inaccessible through externally applied treatments. Trees infected with fire blight should be kept under close monitoring, as the disease can flare up suddenly. Even in best-case scenarios, fire blight can only be sup- pressed but not controlled. What to look for • Disease attacks all above ground parts of the tree • Leaves blacken and curl, giving a fire-scorched appearance • Infected branches blacken and curl into a “shepherds crook” Branches blacken and curl into a • Small to large cankers form on the branches and trunk “shepherds crook” • Succulent growth turns to a brown or black color and wilts • Lesions forming on fruit Treatment and Prevention • Select varieties of trees that are less susceptible to fire blight. • Reduce stress on plants through proper watering and mulching • Reduce growth rate with application of Cambistat™ Growth Regulator • Limit pruning to reasonable doses to reduce sprouting • Remove all cankers and diseased branches o Sanitize pruning equipment between each cut Disease overwinters in Infection gives leaves a fire-scorched Life Cycle old cankers appearance In Spring, bacteria oozes out from cankers and is spread by insects and rain to nearby trees Bacteria travels through branches into the main stem and causes cankers New infection points are blossoms, fresh wounds or natural openings 952-922-3810 © Rainbow Treecare, All Rights Reserved www.rainbowtreecare.com V-01A.
    [Show full text]