Plant Disease Information

Many of the ornamental trees and evergreens in your landscape are susceptible to plant diseases which can eventually cause them to fail and die. What can be more upsetting than watching your valuable trees become weakened by infection? Disease usually begins when a fungus attacks the living tissue of trees and ornamentals, causing leaf or needle drop, cankers, damaged buds or root rot.

Environmental conditions and weather are often critical factors.

Infected trees can then spread the disease as the fungal spores travel on air currents or via root and soil contact.  Some plant diseases are passed between different host plants, such as cedar-apple rust and some contaminate the soil, such as phytophthora root rot. Conditions like humidity, drought, poor pH, overcrowding, compaction, flooding, or nutrient deficiency can also weaken trees and cause disease to flourish.

It is vital to establish a plant health care program that includes proper diagnosis and gets the right treatment on at the right time.

This is where Fox Tree comes in.

At Fox Tree Service we will:

  • Perform a site evaluation and plant diagnosis to determine correct treatment.
  • Schedule and implement a proper treatment program for individual trees and ornamentals as needed.
  • Implement proper preventive techniques in order to reduce susceptibility to disease.

Browse through our pictures below to see if you can identify any of these plant diseases within your landscape. Please feel free to contact our team of specialists.

Sycamore Anthracnose

Sycamore Anthracnose Sycamore anthracnose is a leaf and branch disease that causes leaf drop and  twig dieback. It can affect up to 90% of a tree’s new growth. The disease is usually not fatal and trees defend themselves by dropping infected leaves and pushing out a second set of leaves. However, repeat infections can cause aesthetic harm to a tree and make the tree more susceptible to other diseases and pests. The disease infects the trees' leaves during the [...]

Verticillium Wilt

  Verticillium Wilt on Silver Maple Verticillium Wilt within Phloem Verticillium wilt is a soil borne fungus that can exist in the soil almost indefinitely. In our area we see it most commonly on maple, ash, and redbud. Although verticillium wilt can be found in most soils, it is not usually a problem for woody plants in forested areas, but can be a serious problem in landscaped areas as infected soil is brought in by building [...]

Apple (Venturia) Scab

  Apple Scab     A destructive leaf and fruit disease which can cause defoliation in mid-summer. Infection starts with olive-green spots with indefinite borders which become more prominent and darken to a greenish black. Severe spotting will cause leaves to senesce and fall off. Spots on young fruit will cause deformation and cracking. Wet spring weather, fog, lack of air-flow through tree, and humidity are contributing factors. Spray treatments can help but usually take several years to be [...]

Tar Spots

  Tar Spots Several different fungi in the genus Rhytisma infect the leaves of maples and cause raised, black spots to form on upper leaf surfaces. The diseases are called "tar spots" because their appearance so closely resemble droplets of tar on leaf surfaces. Tar spot alone is rarely serious enough to threaten the health of trees, but sometimes there can be so many spots that the tree becomes unsightly. Heavy infections can also cause early leaf drop-- [...]

Swiss Needlecast

  Swiss Needlecast Needle infecting fungus with symptoms that are usually evident in late winter and early spring and appear on previous year’s or two-year-old needles. Affected needles appear yellow or mottled and gradually turn brown, often with a "dirty" appearance. When the undersides of the needles are examined with a hand lens, two bands of round, black fruiting bodies can be seen on either side of the midrib. With the naked eye, these bands look like "dirt." [...]

Sirococcus Tip Blight

  Sirococcus Tip Blight Sirococcus shoot blight, caused by the fungus Sirococcus strobilinus, affects conifers in the Northern United States and southern Canada. The fungus infects the new shoots; diseased seedlings and saplings are especially affected. Trees that do not die often become misshapen. On older trees, the lower branches are often killed as a result of multiple infections. The fungus causes shoot dieback and stem and branch cankers on the current year's growth. The needles on the [...]

Shothole Fungus

  Shothole Fungus on Cherry Leaves A type of leaf spot that results in small, pinpoint lesions on the leaves. Typically, the black spots fall out, giving the leaf a shot-hole appearance. Leaves with multiple infections turn light green, then yellow, and drop from the tree. Defoliation can affect tree health and lessen winter hardiness. Spots first appear in the spring as the new leaves approach full size. This disease is made worse by mild, wet weather. New [...]

Rose Rust

  Rose Rust Rose rust is a fungal disease caused by several species of Phragmidium. Symptoms can develop on leaves and any other green parts of the plant. Under favorable conditions, rust symptoms can appear on the entire plant. Small, orange pustules develop on both leaf surfaces in early spring. These gradually enlarge and become more pronounced on the lower surface of the leaf. Chlorotic or mottled areas can also develop on the upper surface of the leaf. [...]

Rhabdocline Needlecast

  Rhabdocline Needlecast Needle infecting fungus with symptoms that first become apparent in late fall or early winter as yellow spots or flecks on one or both surfaces of current-season needles. The chlorotic spots gradually turn reddish-brown and can range from 1-2 mm or can encompass the entire needle. A distinctive diagnostic characteristic is the sharp border between the healthy green tissue and the infected brown tissue. Discolored needles are most conspicuous in early spring. Symptoms are often [...]

Privet Anthracnose

Fungus disease causing blighting of twigs, development of cankers on stems and drying of leaves which cling to stems. Tiny yellow, spindle-shaped larvae and dark brown to black adults (with a bright red band) can be sufficiently damaging to give privet a grayish/dusty appearance. Close-up, the foliage looks flecked or stippled.  Spray treatments recommended.  (no image available)

Powdery Mildew

  Powdery Mildew A dusty white to gray coating over leaf surfaces or other plant parts causing stunting and distortion of leaves, buds, growing tips, and fruit. Affects many different plant species. Spray treatments recommended.        

Phytophthora Root Rot

  Phytophthora Rot Symptoms in Rhododendron A soil borne pathogen often brought in on container grown plants or caused by over-watering or poor drainage. Infection often results in the death of the plant, with earlier symptoms including wilting, yellowing and retention of dried foliage and darkening of young feeder roots and occasionally the larger roots. Phytophthora cinnamomi requires moist soil conditions and warm temperatures to be active, but damage caused by the disease most often occurs in summer [...]

Peach Leaf Curl

  Peach Leaf Curl A leaf disease which attacks members of the prunus family. This fungus destroys young leaves. New leaves will develop, however, their growth reduces established food reserves, weakens the tree, and may reduce yield. Defoliation by peach leaf curl in successive seasons may kill the tree. Infected leaves, which begin appearing in mid-May, are easily distinguished from healthy leaves in that they are curled, puckered and thicker than normal. Deformed areas are red to yellow [...]

Oak Anthracnose

  Oak Anthracnose White oaks are the most susceptible of many oak species to this leaf blotching disease. Twig infections occur but are not significant except as sources of overwintering fungal inoculum from year to year. Leaves and shoots are infected during cool, wet spring conditions causing leaf blotches that often are strictly delimited by leaf veins. Eventually, lesions become a papery tan color and some leaf shriveling occurs. Multiple cycles of infection can occur. Just as leaves [...]

Leucostoma & Cytospora Cankers

  Cytospora Canker Leucostoma canker is a devastating disease of Colorado blue, Norway and white spruce and can occasionally be found on other conifers. Trees infected with this fungus will generally first exhibit browned needles (sometimes with a pinkish cast) that fall during the first winter. This symptom usually starts at the bottom and then progresses upwards. Occasionally upper branches will be infected first, but this is rare. The dry brittle twigs contrast sharply with adjacent branches that [...]

Kabatina & Phomopsis Tip Blight

  Phomopsis Tip Blight A tip blight that attacks junipers, especially rug junipers, in landscape plantings and can occur on plants of all ages. Symptoms include browning of needles and tip and branch dieback. Infected tissues develop an overall ash-brown appearance. Infection of the youngest growth is most common although older wood and entire branches can be attacked. In extreme cases the entire plant is killed. Plants under stress due to environmental factors (e.g., drought, excess moisture, growing [...]

Fire Blight

      Fire Blight A significant bacterial infection of crabapples and apples which causes dead areas in crown and dead branches. Usually associated with other factors (stress, irrigation, etc.) Causes blossom blight, shoot blight and dieback of entire areas of crown. Look for sticky bacterial ooze on twigs and fruit. Sanitation pruning or replacement recommended (no effective spray treatment at this time.)       

Dogwood Spot Anthracnose

  Dogwood Spot Anthracnose Elsinoe corni causes the disease known as spot anthracnose, different in many ways from dogwood anthracnose. Infected flower buds do not open or they produce stunted, malformed bracts with numerous small, circular to elongated tan spots with purple to brown borders. There may be up to 50 spots on a bract. Leaf spots have slightly raised purplish edges paling to yellow-gray at centers. The centers will often fall out producing a shot-hole effect. There [...]

Dogwood Anthracnose

  Dogwood Anthracnose A leaf and twig disease that is extremely harmful to flowering dogwoods. Usually, Kousa dogwoods are resistant to infection. Shortly after the leaves have expanded (mid-late May and June), spots and blotches of varying shape and size appear on infected trees. In some cases, entire leaves may become infected and die. Many drooping, brown, dried leaves remain on the stem throughout the fall and winter. When the whole leaf is affected, the infection may then [...]

Diplodia or Sphaeropsis Tip Blight

  Diplodia Tip Blight Diplodia tip blight, also called Sphaeropsis blight, can be a destructive and devastating disease of certain pines. Trees of all ages are susceptible, although older trees frequently sustain greater damage and disfigurement. Diplodia tip blight is caused by the fungus Sphaeropsis sapinea. This fungus usually attacks only mature trees, although it is more damaging to trees that have been under stress from drought, excessive soil moisture, root restriction, other site problems or stresses. Symptoms often [...]

Crown Gall

    Crown Gall on Ilex A bacteria caused infection that causes large, corky galls up to several inches in diameter to appear at the base of the plant and on the stems and roots. The galls are rounded, with a rough, irregular surface. Plants with numerous galls are weak, growth is slowed and leaves turn yellow. Branches may die back. The galls disrupt the flow of water and nutrients to the top of the plant. The bacteria [...]

Cercospora Leaf Spot

  Cercospora Leaf Spot A number of tree species, both deciduous and evergreen, are subject to attack by cercospora spp. foliage diseases, often where spray from irrigation or over-watering are considerations. Spray treatments can help with recovery.       

Cedar Quince Rust of Junipers

  Cedar Quince Rust on Juniper Infected areas on juniper are much less spectacular than with cedar apple rust, with a cushion-like mat of orange fungal growth developing on spherical galls in spring. Galls may be pruned out, but no spray treatment is effective.       

Cedar Quince Rust of Shads & Hawthorns

  Cedar Quince Rust on Shad Cedar quince rust causes great damage to ornamental rosaceous hosts including shads and hawthorns. It is transmitted from nearby junipers and Eastern redcedars. It causes extensive, unsightly fruit infestations, stunting and death of fruits and swelling and distortion of twigs. Infected leaves brown and die. Fruits become covered with orange-pink spore horns. Unsightly spherical cankers developing on stems can last more than one year. New growth is killed off and the trees [...]

Cedar Hawthorn Rust of Junipers

  Cedar Hawthorn Rust on Juniper On junipers, galls are somewhat smaller than with cedar apple rust disease. Galls continue to produce spores on junipers for more than one year, compared to only one season of spore production with cedar apple rust. Galls may be pruned out, but no spray treatment is effective.

Cedar Hawthorn Rust of Hawthorns

  Cedar Hawthorn Rust A significant leaf disease of hawthorns, similar to cedar/apple rust in apples and  brought on by proximity to junipers and Eastern redcedars. Easily seen due to orange lesions on surface and underside of leaves. Wet spring weather, fog, lack of air-flow through tree, and humidity are contributing factors. Spray treatments can help but usually take several years to be effective. Also, removal of dead leaves and fruit is imperative.        

Boxwood Blight

Boxwood Blight Damage A serious disease of boxwoods caused by the fungal pathogen Cylindrocladium buxicola, first seen in the United States in 2011. The disease infects leaves and branches and causes defoliation and dieback. Infected stems sshow long blackish-brown cankers that appear as stripes on stems. Under hot, humid conditions clusters of white spores are visible. The disease can cause repeated defoliation which will cause decline and eventual death. Spray treatments are considered ineffective in landscapes. Best practice involves rogueing out infected [...]

Boxwood Decline

Boxwood Decline A result of attack by various fungi and nematodes, which adds to damage from winter injury and stress on plants especially those in poorly drained sites. This causes stunted growth and dieback. Young foliage turns gray-green or bronze and finally straw color. Old leaves fall prematurely. Middle or top branches die. Sunken cankers form at the soil line or on branches in the crotches where dead leaves accumulate. Wood under the sunken canker is blackened. Protect [...]

Botrytis Blight

  Botrytis Blight Botrytis blight or gray mold is a fungus disease which infects a wide array of herbaceous annual and perennial plants. There are several species of the fungus Botrytis which can cause blights; the most common is Botrytis cinerea. Botrytis infections are favored by cool, rainy spring and summer weather usually around 60F. Gray mold can be particularly damaging when rainy, drizzly weather continues over several days. During wet or humid weather, examine any brown or [...]

Cedar Apple Rust of Junipers & Redcedars

Cedar Apple Rust Gall on Juniper Seen on junipers and Eastern redcedars and transmitted to them from nearby apples and crabapples. Causes tan to brownish round to kidney-shaped fungal galls. With moist weather, gaudy bright orange masses of gelatinous spores develop from these galls, and galls swell to several times their original size. Spore masses are several inches in diameter, with a central core and radiating hornlike tendrils, and are highly visible during moist weather in mid-spring. Galls [...]

Cedar Apple Rust of Apples & Crabapples

A significant leaf and fruit disease of apples and crabapples brought on by proximity to junipers and Eastern redcedars. Easily seen due to orange lesions on surface and underside of leaves. Wet spring weather, fog, lack of air-flow through tree, and humidity are contributing factors. Spray treatments can help but usually take several years to be effective. Also, removal of dead leaves and fruit is imperative.

Brown Rot Blossom & Twig Blight

Brown rot is a common and destructive disease of members of the prunus genus of trees. The brown rot fungus may attack blossoms, fruit, spurs (flower and fruit bearing twigs), and small branches. Symptoms first appear in the spring as the blossoms open. Diseased flowers wilt, turn brown, and may become covered with masses of brownish-gray spores. The diseased flowers usually remain attached into the summer. The disease is most important on fruits just before ripening, during and after harvest. [...]

Blue Stain Fungus

Blue Stain Fungus A fungal disease (Leptographium spp.) introduced into a variety of conifers, notably Japanese black pines, by bark beetles and pinewood nematodes. A the fungus grows, it blocks the sap flow, which eventually kills the tree. The damage can be seen in the wood of the tree, hence the name "blue stain" fungus. There is no treatment for this disease

Bleeding Cankers

  Open cankers that form on the main trunk and large lateral limbs of beech trees and other trees. Can lead to decline and death unless controlled. Usually associated with some kind of stress factor such as age, drought or mechanical injury to tree or root mass. Bark spray treatments with Agri-Fos have been effective. Bleeding Cankers

Black Spot of Roses

Black Spot on Roses Black spot occurs only on roses and is widespread among rose species although some cultivars how more resistance. Symptoms include round to irregular black splotches with fringed margins causing leaf yellowing and defoliation and eventually failure. Treatment involves pruning back diseased canes before winter and an extensive spring/ summer fungicide program.

Black Knot

A fungus (Dibotryon morbosum ) that affects twigs, branches, and fruit spurs of trees of the prunus family, mainly black cherries. It causes abnormal growth of bark and wood tissues, forming knots that turn darker and enlarge and gradually encircle the twig or branch. Sanitation pruning or replacement of tree are only options.

Azalea Gall

Azalea Gall Attacks the newly forming leaves of azaleas and rhododendrons in the spring. Part of the leaf becomes distorted with a bladder-like thickening. When young, the thickened leaf is covered with a white growth. As the galls age they turn brown, dry up and fall to the ground. Sanitation pruning is best treatment

Armillaria Root Rot

Armillaria root rot, or shoestring root rot, is caused by various species of the fungus Armillaria . Most trees are susceptible, but it mainly attacks those under stress from drought, root injury, or recent transplanting. Trees may appear to die quickly. Distinctive fans of fungal growth are seen under bark near the soil line. No treatment available.