Tag Archives: Tree Diseases

Why Do Trees Die

Trees dying from hydraulic failure

Prevent the environment, disease, and insect activity from killing your trees. Knowing why trees die will help you take notice and intervene on threats to your tree’s life.

72tree.com assembled the following information about the many factors that lead to the death of trees, the signs and symptoms of a dying tree, and what to do about it.

1. Tree Diseases

Tree diseases can wreak havoc on your trees, and in some instances, kill them in a single growing season. The following are some of the more common diseases that infect trees:

• Anthracnose (Glomerella cingulata)
• Fire Blight (Erwinia amylovora)
• Diplodia Tip Blight (Sphaeropsis sapinea)
• Oak Wilt (Ceratocystis fagacearum)
• Dutch Elm Disease (Ophiostoma ulmi)
• Canker Diseases (caused by multiple fungal pathogens)

Signs and Symptoms – Trees infected with different diseases will display different symptoms. However, all should be treated with haste to prevent the decline and death of the infected tree. The following symptoms can help you diagnose the disease you are dealing with

Anthracnose – Sunken spots or lesions of various colors in foliage, stems, fruit, and/or flowers. Some infections lead to cankers on twigs, branches, and trunk.

Treatment – If this disease is caught early enough, extensive pruning may halt its progression, allowing the tree to compartmentalize affected areas.

Read more about anthracnose at 72tree.com/symptoms-of-anthracnose/

Fire Blight – Sudden brownish-black withering and death of blossoms, leaves, twigs, fruit spurs, and branches are signs of this disease. Heavily affected trees will appear scorched by fire and may die altogether.

Leaves infected and blackened by fire blight

Treatment – Extensive pruning of affected areas and copper fungicides. However, there is no cure for fire blight. Removal of the tree should be considered before the pathogen spreads to neighboring trees and shrubs.

Further reading on fire blight can be found at 72tree.com/preventing-fire-blight-tree-disease/

Diplodia Tip Blight – This disease infects conifers, first killing needles at the tips of branches. Symptoms typically appear on the lower half of the tree, progressing upwards. When new needles begin expanding, they end up stunted, turn yellow, then tan or brown.

Treatment – This pathogen responds to fungicide treatments. Treatment should start at bud break in the spring for effective control. Pruning out damaged areas, and cones should also be removed, as they hold fungal spores.

This blight can be controlled, but not cured. As with any needle blight disease, the objective of spraying the tree is to break the cycle of infection in emerging needles. Many seasons of treatments are needed before noticeable results are achieved.

Oak Wilt – This disease infects oak trees. It can be identified as mature foliage develops a dark green water-soaked appearance, or may turn pale green or bronze, starting at the leaf margins and progressing toward the center of the leaf. This usually begins on a single branch and quickly spreads throughout the entire crown. Red oaks can die within 4 to 6 weeks after symptoms appear.

Dead leaves on tree with Bretziella fagacearum oak wilt disease

Treatment – Once an oak tree is infected with oak wilt, there is no known treatment capable of ridding the tree of the disease. Infected trees should be professionally removed.

Note: Healthy oaks can be injected with a fungicide known as Propiconazole to suppress oak wilt disease. Since Oak Wilt is spread by root grafts and insect carriers, treat those trees close to infected ones to slow the disease’s spread.

For more oak wilt information, visit 72tree.com/oak-wilt-identification-treatment-prevention/

Dutch Elm Disease (DED) – DED is a vascular wilt disease in trees. External symptoms of infection are yellowing and wilting of leaves on individual branches. These leaves then turn brown and curl up as the branch dies, foliage eventually may drop off.

Treatment – Much like oak wilt, Dutch Elm Disease must be treated proactively before the disease is present in the tree. This disease spreads so quickly that diseased trees may not respond to any form of treatment.

Note: Healthy elms can be professionally treated in the same manner as healthy oaks with the Propiconazole fungicide.

Canker Diseases – Symptoms may include round-to-irregular sunken, swollen, flattened, cracked, discolored, or dead areas (appearing as bruises or open wounds) on tree stems, twigs, limbs, or trunk.

Canker from tree fungi on tree trunks and branches

Treatment – There is no cure for canker diseases on fruit and shade trees, but the disease’s spread can be controlled by pruning out infected areas. In late winter or early spring, carefully remove and destroy infected branches 4 inches below the canker where the tree is releasing amber color sap. If the canker is located on the trunk, request professional help to treat the infected area or remove the tree.

When treating, pruning, or interacting with diseased trees, you can reduce the chances of spreading the disease by:

• Sanitizing all equipment, including gloves, rakes, saws, etc. before and after use
• Destroying (burning) dropped or pruned foliage, twigs, and limbs (never add infected material to compost piles)
• Never spraying infected trees with overhead watering or irrigation

When in doubt, don’t take the chance of making a bad tree situation worse. Reach out to an ISA certified arborist for professional help. Read more about tree fungi control and prevention at 72tree.com/how-to-get-rid-of-tree-fungi/

2. Weather-Related Tree Damage

Trees have spent millennia adapting to their climate and region. That said, severe weather can still inflict significant and sometimes lethal damages to a tree. For example:

Bark Stripping – During catastrophic weather events like tornadoes and hurricanes, bark can be stripped from a side of or from the entire tree, effectively killing it.

Impact Damage – Also, during severe weather events, yard ornaments, statues, bicycles, and even vehicles can be carried by wind or floodwater, impacting and severely damaging the tree’s bark. If enough bark is damaged or stripped from the tree, it will be girdled and quickly die.

Drought – When the weather is dry, trees still need water. Most tree roots live within the first 30-inches of soil, and without water for prolonged periods, a tree can suffer hydraulic failure and die. Proper mulching and increased watering patterns can prevent this peril.

Severe or Repeated Flooding – In contrast to drought, this can lead to the destabilization of a tree’s root plate. When this condition occurs, the tree may develop a lean or suffer windthrow from the slightest wind.

Windthrow – This condition occurs when trees are toppled by wind. When windthrow occurs, a tree is uprooted as it is blown over.

Severe weather can uproot and knock trees over this is known as windthrow one of many ways blowdown occurs

Windsnap – This condition also occurs when trees are toppled by wind. When windsnap occurs, a tree is broken off at the trunk as it is blown down. Proper seasonal pruning activities and crown thinning can significantly reduce the potential for windthrow or windsnap.

For further reading and preventative measures on windthrow and windsnap, read 72tree.com/blowndown-windthrow-windsnap/

3. Boring Insect Infestations

When it comes to tree killers, boring insects are perhaps the most prolific and persistent. Larvae feed in galleries beneath the bark, consuming the tree’s cambium layer, while adults consume the host’s foliage. Aerial views of forested land demonstrate (in large swaths) the devastation these insects are capable of. A boring insect infestation can be identified as follows:

• Adults found in traps (visual confirmation)
• Partially consumed foliage (Leaf notches)
• Chlorosis of foliage in sections of the crown
• Extreme dieback of foliage and stems
• Frass (sawdust) found on the bark from burrowing activities
• Exit holes in tree bark
• Bulging or vertical splits in the bark (over larval galleries)
• Suckers and water sprouts growing in the crown, on the trunk, and/or from the roots
• Woodpecker damage (woodpeckers hunt beetle larvae)
• Squirrel activity (some squirrel species feed on beetle larvae)

Agrilus planipennis emerald ash borer eab boring insect

As larvae feed season after season, they channel through their host’s cambium layer in a zigzag or ribbon pattern (interrupting the flow of water and nutrients. This feeding ultimately leads to a partial or total girdling of the host, resulting in hydraulic failure and death.

Boring Insect Control and Prevention – Due to the larvae’s occult feeding activities, preventing a wood-boring insect infestation is not always possible. However, these practices will help reduce the potential of an infestation:

• Plant well-adapted species of trees not commonly attacked by wood borers in your region.
• Choose and prepare a suitable planting site to avoid tree stress like freeze damage, sunscald, windburn, and other natural stressors.
• Promote your tree’s health with proper watering, mulching, and fertilization methods.
• Use proper seasonal pruning practices (winter/dormant season).
• Avoid mechanical injury to tree trunks from lawnmowers and/or construction.

If you detect a wood-boring insect infestation, contact an ISA certified arborist to not only confirm the infestation but to mobilize local and regional forestry support if needed. Such infestations can cause catastrophic damages in very little time.

Note: In the absence of stressed or ailing trees, boring insects will attack healthy specimens.

Read more exciting literature about boring insects by visiting 72tree.com/metallic-wood-boring-beetles/

4. Lifespan of Trees

While rare, a tree can die of “old age.” However, what is considered old age for one species may be merely infancy for another. Consider the following species and their average lifespan:

• Willow (Salix) 30 years
• Birch (Betula) 40 – 50 years
• Poplar (Populus) 50 years
• Magnolia (Magnolia) 80 – 120 years
• Maple (Acer) 100 – 300 years
• Oak (Quercus) 100 – 300 years
• Ash (Fraxinus) 120 – 300 years
• Aspen (Populus tremuloides) 150 – 200 years
• Walnut (Juglans) 150 to 250 years
• Fig (Ficus carica) 200 years
• Spruce (Picea) 200 years
• Beech (Fagus) 300 – 400 years
• Elm (Ulmus) 300 years
• Pecan (Carya illinoinensis) 300 years
• Pistachio (Pistacia vera) 300 years
• Giant Sequoia (Sequoiadendron giganteum) 500 – 2,000 years
• Sycamore (Platanus occidentalis) 600 years
• Bristlecone (Balfourianae) 5,000+ years

Signs and Symptoms – Trees in decline due to age may present many symptoms, including the following:

• Chlorosis (loss of color in foliage)
• Extreme dieback (multiple dead branches)
• Cladoptosis (randomly falling branches)
• Sudden Death (the tree just dies)

When a tree reaches or surpasses its lifespan it may die

If you have a tree that is nearing or surpassing its lifespan and is in decline, there is little to nothing you can do to save it. When in these circumstances, call on an ISA certified arborist’s expertise to evaluate the tree and recommend a course of action.

Note: While most tree species can outlive a human being, the vast majority of trees succumb to weather, biological, or human interference factors long before reaching their full lifespan.

Saving Dying Trees

In this article, you discovered information about the lifespan of trees, diseases, weather, and insects that are commonly responsible for why trees die.

By taking preventative measures to halt the spread of disease and insect infestations, you are helping your tree to live up to or surpass its lifespan.

When you ignore the warning signs of a dying or sick tree, you risk suffering grave consequences when that tree dies and falls on your property.

Sources:
extension.umn.edu/plant-diseases/oak-wilt-minnesota
mortonarb.org/trees-plants/tree-and-plant-advice/help-diseases/canker-diseases
ipm.ucanr.edu/PMG/PESTNOTES/pn7414.html
fs.usda.gov/naspf/sites/default/files/publications/how_to_identify_and_manage_dutch_elm_disease.pdf
plantclinic.cornell.edu/factsheets/sphaeropsisdiplodia.pdf

Common Maple Tree Diseases, Symptoms, Treatment, and Prevention

Red maple tree acer rubrum health and diseases

Stop your maple tree from needlessly dying. If caught in time, diseases that attack maples can be treated with success.

72tree.com of Alpharetta Ga, assembled the following list of diseases that affect maple trees, how to identify, treat, and prevent them.

Why do My Maple Tree Leaves Have Spots?

One of the easiest ways to detect maple tree diseases is through irregularities in shape or size, spots, and/or blemishes on the tree’s foliage.

The following diseases may cause spots to appear on your maple tree’s foliage:

Leaf Spot (Phyllosticta minima) – This fungal infection causes round spots about a quarter of an inch in diameter to appear on leaves. These spots will have a pronounced purple border and blackish dots in the center of the spot (fungal fruiting structures).

Treatment: Before fall, prune dead twigs, stems, and branches. Collect all clippings and destroy them (burning them is highly recommended) to prevent the spread of the fungus.

Have the tree evaluated to determine the extent of the infection and whether further action like using fungicides should be taken to protect your tree and surrounding landscape.

Maple tree infected with leaf spot phyllosticta minima disease

NOTE: Sanitize all equipment, including gloves and protective clothing that come in contact with an infected tree and its foliage.

Anthracnose (Aureobasidium apocryptum or Discula – Gloeosporium) – Anthracnose is a fungal infection that causes purple or brown streaks to occur alongside and between leaf veins. In some maple species, drought and heat stress can produce similar symptoms. You can confirm an anthracnose infection by locating small, brown fungal fruiting structures near the veins of affected leaves.

Treatment: The same measures and precautions for leaf spot should be used in the treatment of anthracnose.

NOTE: Anthracnose can lead to severe defoliation during a wet spring season.

Root Rot (Fomes fomentarius, Ganoderma lucidum, or Laetiporus sulfureus) – Once a fungal infection embeds itself in the trunk or the roots of a maple tree, there are three types of symptoms to watch for:

• Foliage in the entire crown or a section of it may suffer from chlorosis, wilt, die and eventually fall. This happens as the fungi cause hydraulic failure within the roots, trunk, and branches.

• Fungal fruiting structures (mushroom conks) will appear from late spring to mid-fall. For these structures to form, there must be rotting organic material within the tree.

Maple tree root rot with mushroom conks diseased and dying

• Large black ants known as carpenter ants will make a nest for their colony within trees that suffer from heart rot. These ants do not burrow through heartwood, they remove the tissues rotting and softened from the infection.

Treatment: Once root rot or heart rot has been confirmed, have the tree professionally removed as quickly as possible.

NOTE: The presence of carpenter ants and fungal fruiting structures only occur after significant damage has been done to the tree. When the affected tree is within striking distance of your home, places where people congregate, or other structures and vehicles, the situation should be treated as an emergency.

Galls – These spots are irregular growths or swellings that occur from a reaction to tissue feeding or egg-laying by various species of mites and insects (commonly mistaken for fungal infection).

Maple tree disease galls formed on the top side of a leaf

Galls appear in various ways. Each mite or insect species produces a distinctive gall shape and can range from wart-like bumps to felt-like patches to spindle-shaped protrusions. Galls develop in the spring, and once formed, the pest remains protected within the structure. Arborists can often identify which mite or insect has infested your tree by the shape and appearance of the galls.

Treatment: Leaf galls are relatively innocuous and rarely result in any long term damage to the tree. Applications of pesticides are relatively ineffective, as the pests are protected within the gall structure.

The most effective manner of gall removal is to handpick and destroy affected foliage before exit holes form and allow the pest(s) to move on. If the presence of galls is overwhelming, hire a professional tree service to evaluate the situation and recommend a course of action.

Maple Tree Disease Prevention

Maple tree disease prevention begins with good tree care practices. The healthier your tree is, the more vigorously it can fight back against diseases and infestations.

However, when the tree’s defenses fail, here are steps to prevent the disease or infestation from infecting surrounding trees:

• Prune affected limbs (before leaf-drop)
• Burn all pruned limbs and foliage
• Always sanitize pruning equipment after use on an infected tree
• Avoid tracking soil from around infected trees to areas around uninfected trees (many fungi and other pathogens thrive in the soil). Clean boots, protective clothing, tools, and equipment before leaving an infested area
• Replant resistant species after tree removal
• Avoid planting maple trees in areas with a history of tree diseases
• Have annual tree inspections and soil testing performed to detect any issues early on.

Black Spots on Maple Leaves

In this article, you discovered how to identify diseases that cause spots on maple tree leaves, how to treat them, and how to prevent them.

Prevent the decline of your maple tree by knowing what to do when a fungus or pathogen begins showing signs of infection.

Your choice to ignore signs that your tree is diseased or in decline can result in catastrophic fungal outbreaks to your landscape, or costly damages to your property when the tree falls.

Sources:
extension.psu.edu/maple-diseases
hgic.clemson.edu/factsheet/maple-diseases-insect-pests/
pnwhandbooks.org/plantdisease/host-disease/maple-acer-spp-verticillium-wilt

Oak Wilt Identification, Treatment, and Prevention

Bretziella fagacearum oak wilt disease fungus

Don’t let oak wilt (Bretziella fagacearum) kill your tree. While few fungi can bring down the mighty oak tree, this is one of them.

Oak wilt is one of the most destructive tree diseases in the United States, and it’s on the loose, killing oak trees at nearly epidemic proportions. If your oak tree(s) appear to be in trouble, its problems may be caused by a fungus that, if not halted, will kill your tree in a matter of months.

72tree.com gathered essential information about oak wilt disease, how to identify it, treat it, and prevent it.

What is Oak Wilt?

Bretziella fagacearum, formerly known as Ceratocytis fagacearum, is the scientific name for oak wilt, and this fungal disease affects all species of the oak (Quercus) genus by disabling the water conducting system in these trees.

Based upon porosity and leaf shape, oaks are divided into two groups; red oaks and white oaks. Bretziella fagacearum affects these two groups differently:

White Oak Group – The species below that are part of this group have rounded leaf edges and pores clogged by tyloses.

• Quercus alba (the most commonly known white oak species)
• Quercus lobata (California white oak or valley oak)
• Quercus polymorpha (Mexican white oak or Monterrey oak)
• Quercus bicolor (swamp white oak)
• Quercus arizonica (Arizona white oak)
• Quercus garryana (Oregon white oak or Garry oak)

Tyloses are outgrowths on cells of xylem vessels. Tyloses fall from the sides of the cells and seal a tree’s vascular tissue to prevent or reduce damage.

White oak rounded leaves low susceptibility to Bretziella fagacearum

Red Oak Group – The species below that are part of this group have pointed leaf edges and large open pores:

• Quercus falcata (southern red oak)
• Quercus graciliformis (Canby oak or Chisos oak)
• Quercus buckleyi (Texas red oak)
• Quercus rubra (the northern red oak)
• Carnarvonia araliifolia (an Australian rainforest tree)

Red oak pointed leaves highly susceptible to Bretziella fagacearum

Due to the difference in porosity, species in the red oak group are more easily infected by oak wilt and die more quickly than the white oak group species. In fact, infected trees in the red oak group may die off within a single summer season, where those in the white oak group can persist for several years after being infected.

Another difference is that trees in the red oak group produce fungal spore mats that facilitate the “above ground or overland” spread of the pathogen, whereas the trees in the white oak group rarely produce them.

How to Identify Oak Wilt Disease

Oak trees infected with oak wilt present the following symptoms:

• Leaf chlorosis
• Leaf drop (off-season)
• Dieback from the top down
• Veinal necrosis (Live oak species only)

Dead leaves on tree with Bretziella fagacearum oak wilt disease

In most cases of infection, oak leaves will turn pale green and then brown while still attached to the tree. By the time they fall, the tree is likely dead.

This disease is dangerous in that it is extremely fast acting; it can kill a mature oak tree in a matter of two to four months while spreading from tree to tree via grafted roots.

Grafted roots occur when the roots of two or more compatible tree species meet and fuse together. Once roots are grafted, they gain the ability to interchange nutrients, water, and disease to each other.

If you suspect that your oak tree is infected with oak wilt, have your tree inspected by an arborist immediately.

How to Treat Oak Wilt Disease

Once Bretziella fagacearum has infected your tree, your fast action is required to halt this pathogen. There are two principle ways to treat oak wilt disease:

Fungicide Treatment – Propiconazole applications are an effective preventative measure. During the earliest stages of infection, this fungicide is injected through holes drilled in the root flare, to the tree’s water-conducting vascular system.

The success of this treatment is greatly influenced by the health of the tree and the fungicide application rate. Any time holes are drilled into a tree for this type of treatment, a professional should be hired to make sure the fungicide is applied correctly and that the holes do not become sources of further infection or infestation.

Trenching to Sever Root Connections – When a tree has been infected and fungicide treatments are no longer viable, trenching will help stop the pathogen from being transmitted from tree to tree by grafted roots.

Trenching to sever grafted tree roots and prevent oak wilt disease from spreading

After identifying infected trees, a trench should be dug with a trenching machine, ripper bar, rock saw, or walk-behind trencher to a depth of at least 4 feet (trenches deeper than 4 feet may be required in deeper soil), and a minimum 100 foot radius around the infected tree(s).

Healthy trees within the trench are considered high risk and should be uprooted or removed to improve the effectiveness of the barrier. Tree removal should start immediately after trenching, beginning with the trees closest to the trench, and working inward thereafter until all of the trees within the trench have been eliminated.

An oak wilt contamination can be more easily contained when treatment begins early. Trees outside the trenched area should be monitored for several years after the infected area has been treated, and in the event of further infection, the same procedure (trenching and tree removal) should be repeated while the contaminated area is still manageable.

Oak Wilt Disease Prevention

Tree disease prevention begins with tree health. However, when it comes to oak wilt disease, special care must be taken to avoid infecting otherwise healthy trees. The following will help you avoid spreading the Bretziella fagacearum pathogen to your oaks:

Healthy tree free from Bretziella fagacearum oak wilt disease

Tree Health – A healthy tree has defense mechanisms that help it stave off attacks from fungi and insect infestation. Whether it be exuding sap to close wounds made by insects, or compartmentalization to contain invading pathogens, the healthier your tree is, the more effective its defense will be. The following steps help you increase your tree’s vitality:

During prolonged dry seasons:

• Provide weekly deep waterings for your trees.
• Fertilize your trees before the growing season begins (February, and early March).
• Mulch your trees to avoid losing soil moisture.
• Inspect your trees frequently for wounds and weather damage (including surface roots), use tree wound dressing, wax based dressing, or latex paint to seal these wounds.

Pruning Activities – Pruning encourages new growth. However, in the case of oak trees, pruning them may provide an opportunity for Bretziella fagacearum to invade and kill your tree. Adhere to the following guidelines when pruning oak trees:

Oak tree branch cutting and pruning in winter to prevent wilt disease infection

• From February through July, avoid pruning or wounding your oak tree(s). This period is when oak wilt fungal mats are most easily formed, and oak bark beetles (Scolytinae) and sap beetles (nitidulid) are most active.
• Pruning activities should take place during midwinter or extended periods of hot weather in late summer. (these are the periods which present the least threat to your oaks)
• Sterilize all pruning equipment between trees.
• Paint all pruning wounds with a tree wound dressing, wax-based dressing, or latex paint to create an immediate barrier to contaminated beetles or airborne pathogens, regardless of the time of year.
• Freshly cut stumps and wounded surface roots should be dressed immediately, as Bretziella fagacearum can be transmitted from tree to tree through grafted roots.

Diseased Tree Removal – Oak trees that are dead or dying from oak wilt disease should be removed and immediately burned or buried to prevent dissemination of the disease’s spores.

When dealing with infected trees, call on a professional tree service to handle the removal and destruction of these trees. They will also be able to assess the potential risk to surrounding trees and advise you on any further necessary preventative measures.

Firewood Awareness – Avoid purchasing or transporting unseasoned firewood. Since fungal mats may form on unseasoned oak firewood, you could be unintentionally spreading the pathogen to uninfected areas.

Oak tree seasoned firewood does not spread Bretziella fagacearum

Seasoned firewood has been dried for a minimum of one year and poses little to no threat of spreading the oak wilt pathogen.

Oak Tree Disease – Bretziella Fagacearum

Your mighty oak tree can become infected and die in a matter of months. The Bretziella fagacearum fungus can spread by way of insects, airborne spores, and through grafted roots. By the time you identify the problem, you may be dealing with several infected trees on a fast-track to death.

In this article, you discovered vital information about oak wilt disease, how you can identify it, what you need to do to treat it, and prevention tips.

Your slow response to this fast-acting disease can not only result in the death of your tree, but also to the spread of oak wilt to numerous trees in surrounding environments. At the first sign of trouble, call a professional to help you assess the damage and required measures for containment.

Sources:
https://tfsweb.tamu.edu/OakWiltFAQS/
http://www.inspection.gc.ca/plants/plant-pests-invasive-species/diseases/oak-wilt/fact-sheet/eng/1325629194844/1325632464641
https://www.annualreviews.org/doi/abs/10.1146/annurev.en.07.010162.001551?journalCode=ento
https://www.canr.msu.edu/news/oak_wilt_disease_1
http://www.austintexas.gov/blog/oak-wilt-101