Insects & Diseases
Browse insect and disease resources.
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Alfalfa Mosaic Virus
Alfalfa mosaic virus has a broad host range that includes over 600 plant species in 70 families
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Ambrosia Beetle
Granulate ambrosia beetle was introduced to South Carolina from Asia in the early 1970’s.
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Andromeda Lace Bug
Lace bugs are exclusively plant feeders, and while more species occur on herbaceous plants, the most common species occur on the foliage of trees and shrubs.
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Anthracnose
Many deciduous hardwoods are susceptible to a leaf disease called anthracnose that is caused by various species of the fungus Anthracnose.
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Aphids
Many species of aphids or plant lice occur on ornamental trees and shrubs in Pennsylvania.
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Apple Scab
Apple scab is Pennsylvania's most important apple disease, attacking wild and cultivated apple and crabapple.
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Ash Rust
Ash rust is a common fungal disease of all species of ash trees. The disease is rarely destructive enough to warrant special control measures.
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Ash Yellows
Ash yellows is a disease caused by Candidatus fraxinii , which affects the tree's vascular system or its’ phloem sieve tubes. It is presently only found in North America. Ash yellows disease cycle is still a mystery. Experts think it is transmitted by insect vectors such as leaf hoppers which also transmit viruses.
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Azalea and Rhododoendron Diseases
Informational table showing disease name, symptoms, pathogen/cause, and management of Azalea and Rhododendron diseases.
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Azalea Bark Scale
The adult female azalea bark scale is dark red with short legs and antennae and long, sucking mouth-parts.
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Azalea Leafbug
Lace bugs are common pests of a variety of ornamental trees and shrubs. The adults have highly ornamented wings and a hood-like structure covering the head. The entire surface is covered with veins that look like lace.
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Bacterial Blight
Bacterial blight of lilac, also known as shoot or blossom blight, is caused by the bacterium Pseudomonas syringae pv. syringae. The pathogen is capable of causing damage to all types of lilacs including Japanese, Chinese, Persian and common varieties. Some researchers suggest that white flowering varieties may be more susceptible to infection than other varieties. The disease is usually associated with plants that have been stressed by drought conditions, improper fertilization, and/or have been wounded. The pathogen has also been reported on Forsythia, Blueberry, and other ornamental plants.
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Bacterial Leaf Scorch
Leaf scorch, sometimes called marginal leaf burn, describes the death of tissue along the edge of the leaf. This symptom develops when sufficient water does not reach the leaf margin cells. This can occur if 1) there is insufficient moisture in the soil 2) water is lost too quickly from the leaves to be replaced adequately, 3)roots have been killed by plant pathogens, excavation, or compaction or 4) fungi or bacteria invade and plug the water conducting vessels (xylem) in the plant.
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Bagworms
Bagworm is a caterpillar that molts into a moth in the adult stage. They are easiest to identify by the bags they construct as they feed. Damage includes needle discoloration and injury.
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Bald Cypress Rust Mite
This microscopic mite is an eriophyid mite that is most active during the warm season. The mite is active now in Ohio, and characteristic damage is being seen in Illinois. Damage will appear as reddish brown interior needles.
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Bark Beetle
Bark beetles, family Scolytidae, are common pests of conifers (such as pines, Arborvitae, Fir, Juniper, Leyland Cypress) and some attack broadleaf trees. Over 600 species occurring the United States and Canada with approximately 200 in California alone. The most common species infesting pines in urban landscapes
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Beech Bark Disease
Beech bark disease causes significant mortality and defect in American beech, Fagus grandifolia (Ehrh.).
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Beech Leaf Disease
Beech leaf disease (BLD) is caused by an invasive nematode Litylenchus crenatae subsp. mccannii. Nematodes are microscopic roundworms. Most nematodes are free-living, but some are parasites of animals and plants. Most plant parasitic nematodes live in soil moisture films and feed on plant roots. The nematode that causes BLD is unique in that it is found in the foliage of a tree rather than in the roots.
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Beech Scale
The beech scale (Cryptococcus fagisuga Lindinger) was first found in the U.S. in Massachusetts and Maine in the 1930s.
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Black Canker
Black canker of willow (Salix spp.) is caused by the fungus Glomerella miyabeana (Glomerellaceae). In North America and Europe, the black canker pathogen is consistently associated with the willow scab fungus (Venturiaceae: Venturia saliciperda) and together they combine to produce a serious disease of willow known as “willow blight”.
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Black Knot
Black knot is a common fungal disease of Prunus trees including ornamental, edible, and native plum and cherry trees. Hard swollen black galls (tumor like growths) form on branches and occasionally on trunks. Many Prunus trees tolerate black knot. Tolerant trees have many galls throughout the tree with few negative effects on the health of the tree. Some Prunus trees are more severely affected by black knot. In these trees, leaves and shoots wilt and die on branches with galls. Management will vary depending on how severely the tree is affected by black knot.
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Black Leaf Spot
Leaf spot is a common descriptive term applied to a number of diseases affecting the foliage of ornamentals and shade trees. The majority of leaf spots are caused by fungi, but some are caused by bacteria. Some insects also cause damage that appears like a leaf spot disease. Leaf spots on trees are very common and generally do not require spraying. Leafspot may result in some defoliation of a plant. An established plant can tolerate almost complete defoliation if it happens late in the season or not every year. Small or newly planted trees that become defoliated are more at risk of suffering damage until they become established.
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Black Spot
A common disease of roses called black spot is caused by the fungus Diplocarpon rosae. This fungus readily attacks young expanding leaves and young canes. Fungal spores which were formed on infected fallen leaves or on canes are splashed to the new lower leaves of roses in the spring by rain or sprinkler irrigation. The spores must remain wet for several hours in order for the spore to germinate and invade the leaf. If temperatures are warm following infection, symptoms may become visible in 3 days. New spores can form in as few as 10 days after infection. Thus under some conditions the fungus can infect a plant, begin producing new spores, and spread to other leaves within two weeks.
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Black Vine Weevil
The black vine weevil is a serious pest in nurseries and established landscape plantings.
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Bleeding Canker
Phytophthora bleeding canker kills the bark and outer sapwood tissues of trees and shrubs. The most prominent symptom of the disease is dark-colored sap oozing from bark cankers. The fluid is typically reddish-brown and it stains the surrounding bark as it flows downward. Infected bark is often water soaked and stained while the inner sapwood can exhibit a range of abnormal colors (brown, bluish-green, orange and pink) depending on the particular species of Phytophthora present.
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Blight
Stem Blight of Catharanthus rosea (V. rosea, Vinca minor (Periwinkle) and Vinca major (big-leaf or variegated) is caused by the fungus Phoma exigua. Symptoms consist of rapidly expanding, dark brown to black, girdling lesions on stems at the soil line which result in dieback. Stem lesions expand rapidly, spread to the base of new shoots, and cause wilting, browning, and plant death. The pathogen is widespread and the disease is potentially destructive wherever these plants are grown. Stem blight may be so severe that plantings cannot be maintained and must be replaced. Newly planted beds are most susceptible.
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Botryodiplodia Canker
Pathogen—Botryodiplodia canker is caused by fungal species in the genus Botryodiplodia, including B. hypodermia and B. theobromae. Botryodiplodia is the asexual form of the fungus. The sexual states for some of the Botryodiplodia species are Botryosphaeria spp.
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Botryosphaeria Canker
The fungus Botryosphaeria can cause a branch dieback on many woody ornamentals. Cankers girdle and kill twigs and branches of species such as horsechestnut, redbud, dogwood, beech, walnut, tulip poplar, sweetgum, crabapple, pine, oak, rhododendron, azalea, rose, willow, elm, and yew. Small black fungal fruiting structures which contain fungal spores develop in the canker.
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Boxwood Blight
Cylindrocladium pseudonaviculatum infects all aboveground portions of boxwood, but does not appear to infect the roots. Initial symptoms appear as dark or light brown spots or lesions on the leaves. These lesions often have dark borders. Spots enlarge and then coalesce, often with a concentric pattern or a zonate appearance. Infected leaves then turn brown or straw colored, so infected plants look “blighted”. Defoliation often occurs very quickly after foliar symptoms first develop.
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Boxwood Diseases
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Boxwood Leafminer
The boxwood leafminer is a serious pest of Pennsylvania plantings of boxwood.
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Boxwood Psyllid
The boxwood psyllid is a common pest of boxwood, but not considered as destructive as other boxwood pests.
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Boxwood Spider Mite
The boxwood spider mite, Eurytetranychus buxi, becomes active in late April, early May in Oregon. The mites overwinter in the egg stage.
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Bronze Birch Borer
The bronze birch borer is a serious secondary pest of white, paper, and cut leaf weeping birches.
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Brown Rot
On ornamental cherries, the first symptoms often seen are browing and collapse of the blossoms followed closely by death of the small twigs.
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Canker Stain
London plane and sycamore trees are susceptible to a fungus, Ceratocystis fimbriata f. sp. platani, that is lethal.
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Cedar Apple & Cedar Hawthorn Rust
Cedar-apple rust and closely related diseases, cedar-quince, cedar, hawthorn, and Japanese apple rusts are caused by fungi of the genus Gymnosporangium.
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Cercospora
Cercospora leaf spot is a fungal disease that causes brown or tan spots on privet leaves. The spots can be irregular or circular, and may have reddish-purple borders.
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Cercospora Leaf Spot
Cercospora leaf spot is a common disease that affects the leaves of leucothoe plants. It's usually not serious, but can be disfiguring in cool, rainy springs.
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Cherry Leaf Spot
Cherry leaf spot (Blumeriella jaapii) is a fungal disease which infects cherries and plums. Sweet, sour, and ornamental cherries are susceptible to the disease, being most prevalent in sour cherries. The variety of sour cherries that is the most susceptible are the English morello cherries. This is considered a serious disease in the Midwest, New England states, and Canada.
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Cottony Camellia Scale
Cottony camellia scale is a soft scale that feeds on camellia, holly, yew, euonymus, sweetbox, and maple.
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Cottony Maple Leaf Scale
Cottony maple leaf scale females are 3 to 4mm long and 2 to 4mm wide. They are slightly convex and are brown with a yellow-brown ridge down the back. The body is covered with flakes of clear wax. Their eggs are white to pale yellow and are meshed in a white, cottony ovisac which may be up to 5mm wide and 12mm long. Newly hatched nymphs are pale yellow or green and translucent. They closely adhere to the undersides of leaves and are easily overlooked.
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Cottony Maple Scale
The cottony maple scale is a highly modified insect pest that commonly attacks silver and red maples in Ohio.
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Cottony Taxus Scale
Cottony camellia scale (Pulvinaria floccifera), also called cottony taxus scale, is a non-native type of soft scale insect that can be difficult to manage as their waxy body covering shields them from predators and certain pesticides. Learn more about scale insect groups and biology on our Introduction to Scale Insects page. Cottony camellia scale is a common pest of camellia, yew, holly, and several other trees and shrubs. Heavy infestations can cause leaf yellowing. The impacts of honeydew production and the resulting growth of sooty mold will range from being an aesthetic nuisance to suppressing plant growth. Target monitoring and control efforts to the vulnerable crawler stage.
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Crape Myrtle Aphid
Crape myrtles are among the most commonly planted trees in the Southeast. The two main pests are crape myrtle bark scale , which was covered recently, and crape myrtle aphid.
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Crape Myrtle Bark Scale
Crape myrtle bark scale is a felt scale related to azalea bark scale and oak eriococcin scale. They feed on phloem like other “soft scales”, thus the honeydew.
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Cryptomeria Scale
Cryptomeria scale is an armored scale found on the underside of needles.
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Cylindrocladium
Dark spots form on leaves. Lesions on stems can girdle and kill them. Plants are stunted. Leaves yellow and wilt as branches die. Many dark-brown to black lesions form on roots, enlarge, and girdle roots. Longitudinal cracks may
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Cytospora Canker
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Diplodia (Sphaeropsis) Tip Blight on Pine
Austrian, Scots, ponderosa, mugo, red and other 2 and 3-needled pines are susceptible to the killing of shoot tips and branches by the fungus Diplodia pinea (formerly Sphaeropsis sapinea).
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Diplodia Tip Blight
Diplodia (formerly Sphaeropsis) tip blight is caused by the fungus Diplodia pinea. It is the most common and severe disease of pines in Pennsylvania and attacks trees of all ages. Tips of infected current-year shoots will blight. Needles on these dead tips are usually tan to straw colored, shorter than normal, and typically remain attached.
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Dogwood Anthracnose (Discula)
The early symptoms of discula anthracnose begin in mid to late May as leaf spots with tan or purple borders.
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Dogwood Borer
Adults are typical black and yellow clear-winged moth similar to but smaller than adult lesser peach tree borer and peach tree borer, with awing span of only ¾ inch.
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Dogwood Sawfly
Adult sawflies are wasplike. After the second molt, larvae become covered in a white powdery substance.
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Downy Mildew
Downy mildew is the common name for a group of highly specialized obligate parasites of vascular plants.
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Drought
Drought can impact many types of woody plants in landscapes, natural woodlots, and forests.
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Dutch Elm Disease
Dutch elm disease (DED) is one of the most destructive shade tree diseases in North America. The disease affects American…
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Eastern Tent Caterpillar
The Eastern tent caterpillar has been observed in the United States since 1646.
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Elm Bark Beetle
Three species of bark beetles are associated with elms in the United States.
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Elm Leaf Beetle
The elm leaf beetle is an introduced pest that feeds only on species of elm.
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Elm Yellows
Elm yellows symptoms begin in mid to late summer with the chlorosis and drooping of petioles of turgid leaves and…
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Elongate Hemlock Scale
The elongate hemlock scale sometime known as the fiorinia scale, is a serious scaled insect pest of hemlock.
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Emerald Ash Borer
Emerald Ash Borer (EAB) is a destructive, introduced insect of North American ash trees. It has been the cause of widespread ash tree decline and mortality throughout northeastern North America.
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Eriophyid Mites
Eriophyid mites are microscopic mites that often go undetected.
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Euonymus Alatus Scale
Yellowing of foliage and dieback of branched in heavy infestations. Heavily infested plants have been defoliated during the growing season.
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Euonymus Scale
The euonymus scale is a key pest of deciduous and evergreen euonymus.
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European Elm Scale
Mature females are up to 10 mm long oval and grayish-brown with a white waxy fringe ovisac.
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European Pine Sawfly
The most common sawfly species that attacks pines in Pennsylvania is the European pine sawfly.
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European Red Mite
The European red mite (ERM) is the most important mite species attacking tree fruits in North America.
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Excess Water
Excess water can be a serious problem for many woody ornamentals.
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Fall Webworm
The fall webworm is a widely distributed native pest that appears from late summer through early fall. It feeds on many species of deciduous trees and shrubs.
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Filbert Blight
Eastern Filbert Blight is caused by the fungus Anisogramma anomala and is indigenous to the Northeast United States.
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Fire Blight
Fire blight is a disease caused by the bacterium Erwinia amylovora. Twigs, branches, and leaders on trees and shrubs wilt…
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Fletcher Scale
The Fletcher Scale, sometimes referred to as the arborvitae soft scale, is a common pest of arborvitae and yew.
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Foliar Aphids
Many species of aphids or plant lice occur on ornamental trees and shrubs in Pennsylvania.
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Fungus and Mold in Mulch
Bacteria and fungi help organic matter decompose, so it is only natural that such mulches will sometimes have fungi and…
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Gypsy Moth
The gypsy moth was accidentally introduced into Massachusetts in 1869.
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Hawthorn Lace Bug
Lace bugs are common pests of a variety of ornamental trees and shrubs.
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Hawthorn Leafminer
A moderately common pest problem observed on hawthorn trees in May and June is the hawthorn leafminer, Profenusa canadensis. The leafminer is the larval stage of a sawfly. The larvae live inside the leaf causing the leaf tips to turn brown. Leaves appear to be diseased or damaged by frost. However, frass and at certain times even the larvae can be seen between the upper and lower epidermis by holding the leaves up to the sun.
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Hemlock Rust Mite
Adult eriophid mites are minute, yellowish-orange, spindle-shaped mites with four legs.
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Hemlock Woolly Adelgid
Hemlock woolly adelgid is a destructive, introduced pest of forest and ornamental hemlock trees.
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Holly Leaf Spot
The fungi Coniothyrium ilicinum and Phacidium species are two of several that regularly cause leaf spots on holly (Ilex) in…
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Holly Leafminer
Ornamental plantings of holly in Pennsylvania are often damaged by leafmining pests. The native holly leafminer only feeds on the foliage of American holly.
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Honeylocust Plant Bug
The honeylocust plant bug is a key pest of honeylocust.
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Honeylocust Spider Mite
Adult mites that have overwintered are less then 1 mm long and orange.
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Hydrangea Foliar Diseases
An overview of Hydrangea diseases including Botrytis Blight, Cercospora Leaf Spot, Virescence and others.
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Imported Willow Leaf Beetle
Adults and larvae of the imported willow leaf beetle both feed on foliage of willows during the summer months.
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Indian Wax Scale
Indian wax scale insects, Ceroplastes ceriferus, are tiny, brownish-purple females with microscopic legs and a thick covering of sticky, white wax.
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Japanese Beetle
Japanese beetle adults have metallic green bodies with coppery brown wing covers surrounded with 12 white tufts of hair.
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Japanese Cedar Longhorn Beetle
The Japanese cedar longhorned beetle is an exotic insect that bores into trees of the cypress family.
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Japanese Maple Scale
The Japanese maple scale is a recently detected pest of a wide range of woody host plants in Pennsylvania.
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Japanese Mealybug
This species was intercepted 131 times at U. S. ports-of-entry between 1995 and 2012, with specimens originating from Brazil, China,…
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Juglone Toxicity
Walnuts and hickories produce the chemical juglone (5 hydroxy-1,4- napthoquinone), which is exuded from all parts of the plant.
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Juniper Diseases
An overview of Juniper diseases including cedar-apple rust, cercospora blight and more.
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Juniper Scale
The juniper scale, native to Europe, is now distributed throughout the United States. This armored scale insect occasionally becomes a…
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Juniper Twig Blight
Junipers (Juniperus sp.), also known as red cedars are susceptible to a disease that results in the death of twig…
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Kabatina and Phomopsis Twig Blight
The disease is most severe in nursery stock and seedlings where plants are grown closely together.
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Lace Bug
About 160 species of lace bugs have been described in North America.
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Landscaping and Gardening around Walnuts
Walnuts and hickories produce the chemical juglone (5 hydroxy-1,4- napthoquinone), which is exuded from all parts of the plant
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Larch Casebearer
Caterpillars of this species are very small and one of their first actions is to cut off a needle tip…
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Leaf and Flower Gall
Leaf and flower galls are commonly found on many flowering woody hosts, most often on azalea and camellia.
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Leaf Blotch
Small irregular, reddish-brown spots and large blotches with yellow halos form in late June or early July. Most infected leaves…
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Leaf Spot Diseases on English Ivy
The English ivy is a hardy evergreen vine that is grown widely as a ground cover under trees and in…
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Leaf Spot Diseases on Shade Trees
Leaf spot is a common descriptive term applied to a number of diseases affecting the foliage of ornamentals and shade…
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Leafhoppers
Leafhoppers will feed on the new growth of wisteria. The severity of infestation depends on the size of the migrating…
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Leafminer
A moderately common pest problem observed on hawthorn trees in May and June is the hawthorn leafminer, Profenusa canadensis. The…
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Lecanium Scale
The European fruit lecanium is a key soft scale insect pest of shade trees and other woody ornamental plants in…
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Leucostoma (Cytospora Canker)
Cytospora canker is one of the most destructive diseases of peaches, nectarines, apricots, sweet cherries, and plums in Pennsylvania.
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Lichens
https://ag.umass.edu/landscape/fact-sheets/pseudocercospora-leaf-spot-of-mountain-laurel
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Lilac Borer
Adult lilac (ash) borers are moths that vary in color from brown to yellow to orange. They have clear wings…
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Magnolia Scale
The magnolia scale is one of the largest scale insects in the United States. It feeds only on magnolia. This…
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Mimosa Webworm
The mimosa webworm feeds primarily on the leaves on mimosa and honeylocust trees.
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Mountain Laurel Leaf Spot
Leaf Spot on Mountain Laurel will have large, tan to brown spots on leaves with a dark line on their…
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Oak Bark Beetle
Bark beetles, family Scolytidae, are common pests of conifers (such as pines) and some attack broadleaf trees. Over 600 species…
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Obscure Scale
Obscure scale is a key pest of oak in Pennsylvania.
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Overview of Dogwood Diseases
A look at diseases, symptoms, causes and management of diseases that can affect the Dogwood tree.
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Peachtree Borer
The peachtree borer, a native insect, is a major pest of stone fruits in the United States and Canada.
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Pear Sawfly
Pear sawflies feed on hawthorn, serviceberry, pear, and other members of the rose family.
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Pear Scab
Pear scab resembles apple scab in nearly all respects and is caused by the closely related fungus Venturia pirina.
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Pear Trellis Rust
ptoms on pear begin as yellowish-orange leaf spots early in the season. Young fruit and twigs can also be infected.
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Pestalotiopsis
Pestalotiopsis is a type of needle blight fungal disease that is primarily found on arborvitae (Thuja). It is usually considered a secondary disease that attacks foliage that has been injured or weakened by unfavorable weather or growing conditions. The disease may kill the smaller twigs where the infected needles died
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Phyllosticta
Witchhazel blight is caused by a fungus, Phyllosticta hamamelidis. The fungus causes brown lesions bordered by darker brown margins.
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Phytophthora Bleeding Canker
Bleeding Canker is a potentially lethal disease to mature European Beech trees (Fagus sylvatica).
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Phytophthora Root Rot and Crown Dieback
Fungus-like organisms belonging to the genus Phytophthora are soil- or plant-borne and all are plant pathogens.
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Pine Bark Adelgid
A tree heavily infested with pine bark adelgid may have the look of snow on its branches and trunk.
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Pine Bark Beetle
These cylindrical, brown to black beetles are usually very small, 1/6 to 1/8-inch, but they can cause considerable damage. Fortunately,…
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Pine Diplodia Tip Blight
Austrian, Scots, ponderosa, mugho, red and other 2 and 3-needled pines are susceptible to the killing of shoot tips and…
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Pine Needle Scale
The pine needle scale is considered a key pest of pines in landscapes, nurseries, and Christmas tree plantations in Pennsylvania.
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Pine Tube Moth
Individual Pine Tube Moth (Argyrotaenia pinatubana) caterpillars use silk to form a hollow tube by binding together 10 – 20 needles. They then move up and down their silk-lined tube to feed on the tips of the bound needles.
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Powdery Mildew Cross Listing
While some powdery mildews attack a very few specific plants, others have a broad host range and infect many different…
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Privet Rust Mite
The privet rust mite, Aculus ligustri, is a microscopic mite with teeny-weeny, scissor-like mouthparts that it uses to puncture the epidermis of the leaves of ligustrum to feed.
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Procera Root Rot
Procera root rot also known as white pine root decline is caused by a fungus. It infects the inner bark and sapwood of the roots and lower trunk of white pine.
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Red Headed Pine Sawfly
There are several species of sawflies that attack pines in Pennsylvania including the redheaded pine sawfly.
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Rhabdcline Needle Cast
Douglas-fir is the only known host of Rhabdocline. Rhabdocline needle cast infection occurs around bud break, when buds are opening to expose susceptible immature needles
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Rhizosphaera Needle Cast
Rhizosphaera needlecast disease is caused by the fungus Rhizosphaera kalkhoffii Bubak.
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Rhododendron and Azalea Care
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Rhododendron Borer
The rhododendron borer is one of the smallest clearwing borers found in Pennsylvania.
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Rhododendron Lace Bug
Twenty-eight lace bug species have been recorded in Pennsylvania, but only a few are key pests of ornamental evergreen plants like azalea and rhododendron.
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Rhododendron Tip Midge
The rhododendron tip midge is a light-brown, 1.25-mm-long fly.
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Rose Diseases
An overview of the types of diseases that affect the Roses.
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Rose General
Unfortunately, the numerous insects and related pests that attack roses can make growing them “interesting,” if not outright challenging.
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Rose Midge
The rose midge, Dasineura rhodophaga (Coquillett, 1900), is an uncommon but damaging pest of roses.
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Rose Rosette Disease
Rose rosette disease has been spreading through much of the wild rose population of the Midwestern, Southern, and Eastern United States.
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Rose Scale
This insect has a global distribution, and is commonly seen on Rosa and Rubus.
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Rose Spider Mites
Spider mites are tiny 8 legged animals closely related to spiders. Several kinds are important pests of ornamental trees, shrubs and bedding plants. Under favorable conditions spider mites can build up rapidly and seriously threaten plant health.
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Roseslug Sawfly
The common roseslug, Endelomyia aethiops, can be found skeletonizing rose leaves in late spring and early summer.
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Rust
Cedar-apple rust and closely related diseases, cedar-quince, cedar-hawthorn, and Japanese apple rusts are caused by fungi belonging to the genus Gymnosporangium.
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Sapsuckers
The yellow-bellied sapsucker is the only member of the woodpecker family to cause the type of injury from boring numerous drills holes in trees to drink sap.
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Scale Insects Fact Sheet
U.S. quarantine notes This species was intercepted 131 times at U. S. ports-of-entry between 1995 and 2012, with specimens originating from Brazil, China, France, India, Japan, Singapore, South Korea, Togo, and Vietnam.
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Seiridium Canker
Seiridium canker is perhaps the most significant and damaging disease on Leyland cypress. This fungus is commonly associated with both twig cankers and twig dieback.
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Shothole Disease
The shot-hole appearance of the leaves is where the disease-infected tissue dries up and falls out of the center of the leaf spot, leaving a hole about 1/8” inch in diameter. This disease literally appears as though someone were shooting a shotgun at the leaves of your tree, creating a random pattern of small shot-holes.
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Southern Red Mite
The female adult is about 0.38 mm long and resembles a small spider.
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Spider Mites
Spider mites are not insects, and are more closely related to spiders.
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Spiny Witchhazel Gall Aphid
The aphid produces raised ribs or “corrugations” on the upper leaf surface that match deep furrows between the veins.
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Spittlebug
This pest is most commonly recognized when the nymphs make the bubbly spittle masses on small branches of conifers.
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Spotted Lantern Fly
Lycorma delicatula , commonly known as the Spotted Lanternfly (SLF), is a new invasive insect that has spread throughout southeastern Pennsylvania since its discovery in Berks County in 2014. SLF presents a significant threat to Pennsylvania agriculture, including the grape, tree-fruit, hardwood and nursery industries, which collectively are worth nearly $18 billion to the state's economy.
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Spruce Bud Scale
Spruce bud scale may often go unnoticed since their size and color can cause them to be mistaken for buds. They are round, reddish brown in color and are often clustered in-groups of three to eight at the base of new shoots. Lower branches are more often attacked than higher branches. Severe infestations can produce lots of honeydew that will allow sooty mold to grow.
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Spruce Cytospora Canker
Blue and Norway spruces are susceptible to a branch killing disease caused by the fungus Cytospora kunzei.
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Spruce Gall Adelgid
The eastern spruce gall adelgid is a key pest of Norway spruce in northeastern United States.
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Spruce Spider Mite
The Spruce Spider Mite is considered one of the most destructive spider mites in the United States.
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Stigmina Needle Cast
Prior to 1999, when Stigmina lautii was identified in North Carolina on blue spruce, this needle cast pathogen was only known from western Canada on black (P. mariana) and white spruce.
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Swiss Needle Cast
Like most other fungal diseases, Swiss needle cast favors rainy, moist, and cool weather. Fruiting bodies develop through the stomata.
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Sycamore Lacebug
Lace bugs are exclusively plant feeders. The most common species occur on the foliage of trees and shrubs.
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Taxus Mealybug
A small soft bodied insect covered with fine whitish wax, similar in appearance to soft scale.
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Thousand Cankers Disease
Thousand cankers disease (TCD) is a disease complex native to the western United States.
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Thrips
Thrips, order Thysanoptera, are tiny, slender insects with fringed wings.
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Tree Diseases That Cause Hazards
An overview of certain diseases of trees that weaken their structure and create a hazardous situations.
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Tubakia Leaf Spot
Tubakia leaf spot is different than anthracnose, so consultants and homeowners have questioned whether they should be concerned. This disease is not new but is still not as well known as anthracnose.
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Tuliptree Scale
The tuliptree scale is one of the largest soft scale insects in the United States.
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Two-lined Chestnut Borer
Adult two-lined chestnut borers are slender, black beetles with a bluish to greenish hue that are 1/5-1/2 inch (5-13 mm) long with two faint, yellowish stripes along their back. Larvae are legless, white, slender, and about 1 inch (2.5 cm) long when fully grown with two spines at the tip of the abdomen and have an enlarged, flattened front end, characteristic of the Buprestidae.
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Two-Spotted Spider Mite
This plant pest seems to feed on just about everything in the landscape. Two-spotted spider mites reproduce faster and have more generations per year when the weather is hot, consistently in the upper 80's. Its host range is vast including annual flowers, ornamental grasses, herbaceous perennials, and woody trees and shrubs.
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Verticillium Wilt
Early indications that a tree has Verticillium wilt include heavy seed production, leaves that are smaller than normal, and the browning of the margins of leaves.
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Viburnum Leaf Beetle
An invasive species, the viburnum leaf beetle has the potential to become a serious problem in nurseries and landscapes in Pennsylvania.
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Volutella
Leaf blight can be a very destructive disease on pachysandra. The disease is caused by the fungus Volutella pachysandrae, and may be worse where plants are under stress.
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Volutella Blight
Brown to tan spots on the leaves are small at first but enlarge and may cover the entire leaf.
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White Pine Sheath Mite
Eriophyid mites are distinctly different from the typical spider mite. They are extremely small and only have two pairs of legs in all active stages. The body is wedge or carrot shaped and light tan or pinkish
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White Pine Weevil
The white pine weevil is considered the most destructive insect pest of eastern white pine in North America.
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White Prunicola Scale
What was formerly considered to be a single species of scale known as the white peach scale, has been determined to actually involve two species, one commonly known as the white peach scale, Pseudaulacaspis pentagona, and the other, Pseudaulacaspis prunicola, with the suggested common name of white prunicola scale (WPS). The WPS is the species found on Long Island, whereas white peach scale is more southern in its geographic distribution.
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Whitefly
Whiteflies are white insects with pale yellow bodies that are approximately 2 mm long.
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Willow Scab
Willow scab, caused by the fungus Venturia saliciperda, affects Salix species throughout Europe and the eastern United States.
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Winter Injury
Weather conditions during the past few winters have been conducive for injury to woody ornamentals.
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Woolly Beech Aphids
These sap-sucking insects cover themselves with waxy filaments to deter predators.