Articles in category: Insects & Diseases
- Magnolia Scale
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MAGNOLIA SCALE(Neolecanium cornuparvum) Magnolia scale is our largest soft scale insect, reaching ½ inch in length. This scale spends the winter on one-to-two-year-old twigs as tiny, dark-colored nymphs. In the spring, the scales begin to feed,... - Yikes! What's Wrong with That Plant?
Yikes! What's Wrong with That Plant? By Donna Danielson, M.S.Plant Clinic Assistant, The Morton Arboretum To some people, identifying what's wrong with a plant is a complete mystery. Others believe any problem will be solved by an application of...
- Where Are All The Bumble Bees?
Where Are All The Bumble Bees? By Trica BarronPlant Health Care Technician Many of us have noticed that there have been few bumble bees in our gardens this season. They are gentle, slow, clumsy and vividly colored. The loveable bumble bee is...
- Understanding and Identifying Scale Insects on Woody Plants
Understanding and Identifying Scale Insects on Woody Plants Fredric Miller, Ph.D.Professor of HorticultureDepartment of Horticulture ScienceJoliet Junior CollegeJoliet, Illinois 60431 Now that spring is in full swing, we need to be alert for the...
- The Elm Flea Weevil: not to be Confused with Flea Beetles!
The Elm Flea Weevil: not to be Confused with Flea Beetles! By Fredric Miller, Ph.D.Research Associate, Entomology Entomologists have a saying, "there is always one more bug!". With nearly one million classified species of insects so far and...
- Pest Control Decision Making and Managing Scale Insects
Pest Control Decision Making and Managing Scale Insects By Fredric Miller, Ph.D.Professor of HorticultureJoliet Junior College Fall is on its way and colder weather is soon to follow. As we move into the windy, blustery months of early winter, it...
- Overwintering Strategies of Insects and Implications for Integrated Pest Management
Overwintering Strategies of Insects and Implications for Integrated Pest Management By Fredric Miller, Ph.D.Professor of Horticulture, Joliet Junior College and Research Associate, The Morton Arboretum As you sit drinking your morning cup of...
- Japanese Beetles are Here!
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Japanese Beetles are Here! Fredric Miller, Ph.D.Extension EntomologistUniversity of Illinois Adult Japanese beetles began emerging in late June this season and will continue to be around for six to eight weeks. As with many insects, the Japanese... - IPM Propagation - Use of Horticultural Oils in Taxus Propagation
IPM Propagation—Use of Horticultural Oils in Taxus Propagation By Peter LinsnerPlant Production ManagerThe Morton Arboretum Fletcher scale is a common problem in Taxus (Yew) production. Heavily infested plants become stressed causing reduced...
- Biological Control: Utilizing Living Organisms to Control Living Organisms
Biological Control: Utilizing Living Organisms to Control Living Organisms By Daniel ThorpePlant Pathology InternThe Morton Arboretum There is nothing more agonizing than having your plants infested by pests. Whether the plant is grown for...
- Favorite Books to Identify Insect Pests
Favorite Books to Identify Insect Pests By Donna Danielson, M.S.Plant Clinic AssistantThe Morton Arboretum The following list contains our favorite books to identify insect pests on plants. Most of these books do not include chemical controls...
- Verticillium Wilt
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Verticillium Wilt By Karel Jacobs, Ph.D.Plant PathologistThe Morton Arboretum Verticillium Wilt is a serious disease of hundreds of plant species including crop plants and landscape trees and shrubs. Verticillium dahliae is the name of the fungus... - Sudden Oak Death: Yet another introduced disease to be on the look out for.
Sudden Oak Death: Yet another introduced disease to be on the look out for Karel Jacobs, Ph.D.Plant Pathologist, The Morton Arboretum Sudden Oak Death, or SOD as it is known to ‘insiders', is a somewhat misnamed disease caused by what most...
- Mulch, Compost and the Threat of Disease Transmission
Mulch, Compost and the Threat of Disease Transmission By Karel Jacobs, Ph.D.Plant Pathologist Mulching trees and shrubs with wood chips or other organic (derived from once living organisms, like plants) materials are commonplace in landscapes....
- Favorite Books About Plant Diseases
Favorite Books About Plant Diseases By Donna Danielson, M.S.Plant Clinic Assistant Disease identification is much harder than insect identification. Wilted leaves and dying branches can have many causes. To absolutely identify a disease, it...
- Elm Yellows Outbreak in the Chicago Area
Elm Yellows Outbreak in the Chicago Area Karel A. Jacobs, Ph.D.Plant PathologistThe Morton Arboretum I became aware of another lethal elm disease (i.e., not Dutch elm disease) in the fall of 1997 when asked to look at dying American elms in...
- Apple Scab Resistance - Pursuing a Moving Target
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Apple Scab Resistance—Pursuing a Moving Target By Susan J. Wiegrefe, Ph. D.Morton Arboretum Tree Breeder It's not just your imagination—apples and crabapples have been infected with apple scab more than usual in the recent years. The fungal... - Armillaria Root Rot and Native Oaks
Armillaria Root Rot and Native Oaks By Karel Jacobs, Ph.D.Plant PathologistThe Morton Arboretum Concern over declining oaks is impossible to soothe. Rare is the tree so long-lived and evocative in its gnarled architecture. Maybe only the squirrel,...
- Cottony Maple Scale (Pulvinaria Innumerabilis)
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COTTONY MAPLE SCALE (Pulvinaria innumerabilis) The primary host of cottony maple scale is the silver (or soft) maple and boxelder. It can also infest other maples, white ash, hackberry, dogwood, beech, apple, oak, linden, elm, black and honey... - Viburnum Crown Borers (Synanthedon viburni and Synanthedon fatifera)
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DESCRIPTION Viburnum borers are wood-boring insects that feed on the lower part of viburnum trunks, branches, and roots. There are two species of viburnum crown borers which have a similar look and biology. The adult viburnum clearwing borer... - Spruce Gall Adelgid
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Spruce Gall Adelgid Two species of small, soft-bodied insects infest spruce species during the course of rather complicated life cycles. These aphid-like insects called adelgids, produce galls that can disfigure and even kill their hosts. The two... - Elm Leaf Beetle (Xanthogaleruca luteola)
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The elm leaf beetle is often considered as much of an indoor nuisance as a garden pest since large numbers of adults migrate into homes seeking a protected place to overwinter. Outdoors, both adults and larvae feed on the emerging leaves of... - Carpenter Ants (Camponotus pennsylvanicus)
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While often associated with wood that is dead or rotting, the carpenter ant is not the source of the deterioration, as is generally thought. Wood that is soft and moist is the carpenter ant’s preferred nesting site, and it is the telltale sawdust... - Periodical Cicadas (Magicicada septendecim)
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Each year, somewhere in the United States east of the Rocky Mountains, a brood of the periodical cicadas emerges. Periodical cicadas have two distinct races based on required time to complete their life cycle: a 17-year northern race and a 13-year... - Slugs
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Anyone who has watched their hosta foliage turn “lacy” has experienced the work of slugs. Slugs, a common plant pest in wet weather, are snails without shells. They are mollusks, which means they are related to oysters, octopi, and... - Scale Insects
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DESCRIPTION There are many species of scale insects that feed on a wide range of host plants. Scale insects are a unique group, that look quite different from other insects. In their juvenile growth stage, they are referred to as "crawlers". As... - Gypsy Moths
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The gypsy moth, Lymantria dispar, was introduced into this country in 1869 and has since become a serious pest in the northeastern part of the United States. In some areas it has changed the ecology of native forests, defoliating more than 13... - Pine Sawflies
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DESCRIPTION There are more than 100 species of sawflies known in the United States, and the most common feed on conifer foliage. In reality, the sawfly is not a fly, but in the order Hymenoptera, which includes ants, wasps, and bees. It gets the... - Pine Moths
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Although there are many species of small moths that infest conifers, two in particular are troublesome to pines in the Midwest: the European pine shoot moth and the Zimmerman pine moth. The larvae of both species inflict damage by boring into the... - Mites
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DESCRIPTION There are several different species of mites that can cause damage to a wide variety of ornamental plants, including deciduous trees and shrubs, evergreens, and garden plants. As the name implies, mites are so small that they often... - Minor Plant Pest Problems
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There are a number of conditions in gardens that may affect the appearance of a plant, but not pose a serious threat to its overall health. These conditions have a variety of causes, from environment and climate, to insects and bacteria or fungi.... - Japanese Beetles
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The Japanese beetle is native to Japan and was accidentally introduced into the United States in 1916. Since that time it has slowly spread from southern Maine to Georgia, and westward from Missouri to Minnesota. DESCRIPTION Japanese beetle adults... - Honeysuckle Aphid (Hyadaphis tataricae)
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In recent years, honeysuckle shrubs have become prone to infestations of the honeysuckle aphid, whose feeding habits cause a serious distortion of growing tips known as “witches’ brooms”. While attacks from the honeysuckle aphid do not usually... - Honey Locust Plant Bug (Diaphnocoris chlorionis)
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DESCRIPTION The honey locust plant bug is approximately 1/8 inch long and pale to light green when full grown. There are two stages: the nymph and adult. The nymph is a miniature replica of the adult. Both stages are quite active and will fly when... - Cankerworms
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SYMPTOMS Commonly known as the “inchworm”, there are actually two species of cankerworms that attack fruit and ornamental trees: the “fall” and “spring” cankerworms. Their names refer to the season during which their eggs are laid,... - Bronze Birch Borer (Agrilus anxius)
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This native insect is a serious pest of ornamental birch (Betula spp.), one of the more popular trees found in landscapes today. Grown as a specimen, white-barked birch is often sited in heavy clay soils or grown under other adverse conditions,... - Black Vine Weevil (Otiorhynchus sulcatus)
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One of the most destructive and widespread root weevils in the northern U.S. and Canada, the black vine weevil, can cause damage to susceptible plants at both the adult and larval stages of its life cycle. Feeding on a wide range of herbaceous and... - Boxelder Bugs (Leptocoris trivittatus)
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While the boxelder bug can cause minor damage to its preferred host plant, the boxelder tree (Acer negundo), it is primarily a nuisance for the homeowner who finds large colonies of adults seeking places to overwinter. The boxelder bug will seek... - Aphids (Aphis spp.)
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There are many species of aphids, varying in size, color and habitat. As individuals, they do little harm to a host plant, but large infestations can produce severe damage. While their behavior is determined largely by food preference and feeding... - Asian Longhorned Beetle (Anoplophora glabripennis)
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The Asian longhorned beetle is an insect that can do very serious damage and even kill trees while it is in its larval stage. It was first discovered in the Ravenswood area of Chicago in 1998, as well as in two Chicago suburbs, Addison and Summit. A... - European Elm Flea Weevil (Orchestes alni)
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DESCRIPTION The European elm flea weevil has been a pest on elms in the upper Midwest only since 2003, though it was first discovered in the U.S. in 1982. It is especially common on Siberian elms. The insects are tiny weevils about 1/16th of an... - Borers
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Borers are a group of insect pests that spend part of their adult or larval life stage feeding inside roots and branches, or tunneling beneath the bark or into the heartwood of many trees and shrubs. Many species of boring insects are capable of... - Plant Galls
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Description Galls are abnormal growths that occur on leaves, twigs, roots, or flowers of many plants. Most galls are caused by irritation and/or stimulation of plant cells due to feeding or egg-laying by insects such as aphids, midges, wasps, or... - Wetwood
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Wetwood, also known as slime flux, is a very common bacterial disease that occurs in many kinds of trees. Nearly all elm and poplar species are affected, as are numerous other trees including crabapple, beech, birch, maple, dogwood, horsechestnut,... - Verticillium Wilt
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Verticillium wilt is a serious fungal disease that causes injury or death to many plants, including trees, shrubs, ground covers, vines, fruits and vegetables, and herbaceous ornamentals. It is a disease of the xylem, or water-conducting tissues, in... - Spruce Diseases
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CYTOSPORA CANKER Cytospora canker, caused by the fungus Cytospora kunzei (also known as Valsa kunzei var. piceae), is the most prevalent and destructive fungal disease of Norway and Colorado blue spruce. Occasionally, Cytospora canker is found on... - Diplodia Tip Blight
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Diplodia tip blight, previously known as Sphaeropsis tip blight, is a common fungal disease of stressed conifers, especially pines with needles in bunches of 2’s and 3’s. Austrian pine (Pinus nigra) is the most susceptible host, although the... - Powdery Mildews
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Powdery mildews are caused by over 1,000 species of fungi that affect most landscape plants. Most grow only on the upper leaf surface and stems of plants, and do not invade the leaf tissue of the host plant. In most cases, powdery mildew is not a... - Pine Diseases
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Besides Sphaeropsis tip blight (see leaflet #60), common pine diseases found in the Chicago area are pine wilt, Dothistroma needlecast, and Lophodermium needlecast. PINE WILT Pine wilt is a serious disease caused by the pinewood nematode,... - Oak Wilt
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Oak wilt, caused by the fungus Ceratocystis fagacearum, has become a serious disease threat to oaks in the eastern and central United States. While the spread of oak wilt has not been rapid, it can be found in all counties of Illinois and 18 other... - Ground Cover Diseases
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Ground covers often make our jobs as gardeners easier by preventing weeds, holding soil in place, and helping to moderate soil temperature extremes. Ground covers, however, are not maintenance free. Like all plants, they can be susceptible to... - Cedar-Apple and Related Rust Diseases
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There are several cedar-rust diseases that spend part of their life cycle on Eastern red cedar (Juniperus virginiana) and other junipers, and another part of their life cycle on apple, hawthorn, and other members of the rose family. Both hosts are... - Canker Diseases
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Canker diseases are common, widespread, and destructive to a wide range of trees and shrubs. A ‘canker’ is really a symptom of an injury often associated with an open wound that has become infected by a fungal or bacterial pathogen. Canker... - Black Knot of Ornamental Cherry and Plum
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Black knot is a serious disease of plum and cherry trees (Prunus species) throughout the United States. Black knot is a disease that gets progressively worse each year unless controlled, and it will eventually stunt or kill the tree. It is... - Apple Scab
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Apple scab is one of the more serious diseases of ornamental crabapples. It is caused by the fungus Venturia inaequalis. Apple scab mainly affects members of the rose family, including nearly all commercial cultivars of apple (Malus spp.), crabapple... - Tent or Web-Making Caterpillars
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Two of the most common pests of deciduous trees are the Eastern tent caterpillar and the fall webworm, whose conspicuous gauzy tents deface roadside trees, home landscape trees, and fruit tree orchards. Although people often confuse the two or... - Bagworms (Thyridopteryx ephemeraeformis)
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Description Bagworms are pests on many kinds of conifers and deciduous trees, though they’re most frequently found on arborvitae and junipers. The dark brown bagworm caterpillars are 1/8 to 1/4 inch long when they first hatch, eventually... - Ash Flower Galls
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Many homeowners become alarmed when they see green or brown clusters hanging from branches on their ash trees. The clusters are ash flower galls and do not harm the tree. Most ash trees are dioecious – that is, the tree has either all male flowers... - Juniper Tip Blight
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Juniper tip blight is a common disease of junipers found in most states east of the Mississippi River. There are many varieties of junipers susceptible to tip blights; however, the disease is most serious on young or newly transplanted plants. As... - Fire Blight
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Fire blight is caused by a bacterium, Erwinia amylovora, and it only affects members of the rose family. This includes more than 75 different kinds of trees and shrubs, including apple and crabapple (Malus), cotoneaster (Cotoneaster), hawthorn... - Dutch Elm Disease
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This disease is not of Dutch origin, but because early work on the disease was done by Dutch pathologists in the 1920s, the disease has been called Dutch elm disease (DED). In all probability the disease is of Asiatic origin. DED is caused by a... - Anthracnose of Shade Trees
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One of the most common and unsightly diseases of shade trees is anthracnose. Anthracnose is a foliar disease caused by several species of fungi whose spores, when released, infect newly emerging leaves. The disease, which becomes active in spring,... - Emerald Ash Borer Background Information
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Invasive species Awareness Month (May) "Where Have All the Ashes Gone?". Andrea Dierich, Forest Pest Outreach and Survey Project Coordinator at The Morton Arboretum talks about Emerald Ash Borer. (8:24... - Symptoms of Emerald Ash Borer Infestation
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Usually EAB infestations go undetected until the trees begin to show symptoms of infestation. It may take at least one year before symptoms first appear. The symptoms below indicate the possible presence of emerald ash borer: Jagged... - Emerald Ash Borer Identification
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Adults are bright metallic green beetles that are approximately 1/3 inch long and 1/16 inch wide. They have flat backs and rounded abdomens. They are present from mid-May through late July. Larvae reach a length of approximately 1 inch and are... - Ash Tree Identification
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Every tree species has a unique combination of defining characteristics. Variations in leaf size, shape, and arrangement can assist in identification. Use the following images comparing ash to other trees in determining if your tree is an ash. Ash... - EAB Educational Materials & Hubs
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Pamphlets and other educational materials are available for municipal foresters or others who must educate the public about EAB. Below is a list of products, some in limited quantities, and a list of hubs. Note (very important): contact... - Latest EAB Information for Municipal Foresters
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The Morton Arboretum suggests these steps for municipal foresters: Conduct a public education campaign by helping homeowners understand what an ash tree and EAB look like. To help you educate village managers and other officials about the scope... - EAB Advice to Homeowners
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The Morton Arboretum suggests these steps: Do not move firewood. Campers or vacationers who head to their summer homes should acquire firewood from the local area. Familiarize yourself with ash trees. Familiarize yourself with the... - Emerald Ash Borer — Additional News
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Insecticidal ControlHomeowners and others have asked whether insecticides are useful in combating EAB. Experts have compiled a fact sheet to answer your questions. [PDF] Replacement Tree ListsMany property owners ask what kinds of replacement... - Emerald Ash Borer Now in 15 States
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Officials continue to confirm additional infestations of the Emerald ash borer (EAB), an invasive pest that has left tens of millions of ash trees dead in the United States. Fifteen states now reporting infestations are: Illinois, Indiana,...