Tag Archives: Fire Blight


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10 Alpharetta Tree Diseases – Identification & Treatment

Tree diseases cause severe damage to branches foliage and fruit appearing as scabs die back and mushroom conks

Need help identifying a potential tree disease? Recognizing when your tree is diseased will help you take prompt action to prune, treat, or call in an arborist or professional to halt the disease’s progression.

72tree.com gathered the following information to help you identify tree diseases and how to effectively treat your tree to prevent further decline or death.

What Does a Diseased Tree Look Like?

Diseased trees can physically manifest their ailments in multiple ways. Some common indicators of a diseased tree include:

• Low hanging dead or dying branches (lacking bark and have no leaves)
• Dropping dying or dead branches
• Weak, V-shaped branch unions, where two branches have grown together
• An excessively thick or dense canopy that could easily break
• Excessive wilting
• Leaf problems (spots, holes, odd colored, or deformed leaves)
• Fuzzy or moldy patches
• Water sprouts (water shoots) grow on the trunk or roots

Note: An alarming sign of advanced tree disease is when a tree starts to lean. This is an urgent problem requiring immediate professional attention.

Common Tree Diseases

The following tree diseases and their host species may require a professional assessment to determine an effective treatment plan. For an arborist in Alpharetta, we can help, or find a local arborist by visiting treesaregood.org/findanarborist. A third option is to collect samples of the tree and have them analyzed at your local university extension.

Consider the following 10 tree diseases:

1. Dutch Elm Disease (DED) (Ophiostoma ulmi) – A fungal disease that infects elm trees, causes rapid decline and death and is spread by bark beetles.

Tree diseases cause severe damage to branches foliage and fruit like Dutch elm disease

Treatment: When caught early, DED infections can be pruned out, and the tree can be protected by fungicides. Several DED-resistant elm varieties are available.

2. Oak Wilt (Ceratocystis fagacearum) – A fungal disease that affects oak trees and is spread through root grafts and sap-feeding, boring beetles.

Treatment: Trees infected with or have died from oak wilt should be completely removed, properly treated, and destroyed to prevent spore mat development. These treatments may include debarking, chipping or splitting, drying, and burning the wood.

3. Apple Scab (Venturia inaequalis) – A fungal disease that affects apple trees and causes leaf spotting and premature leaf drop.

Treatment: Scab control for edible apple and crabapple trees includes captan, lime-sulfur, and powdered or wettable sulfur applications.

Tree diseases cause severe damage to branches foliage and fruit like apple scab

4. Pine Wilt Disease (Bursaphelenchus xylophilus) – A bacterial disease that affects pine trees and is spread by pinewood nematodes and pine sawyer beetles.

Treatment: Once infected with pinewood nematodes, pesticides are no longer effective. Once a tree is infected, there is no cure for pine wilt, and dead trees left in the landscape become sources of nematodes and pine sawyer beetles. Diseased trees should be destroyed by burning, chipping, or burying.

5. Chestnut Blight (Cryphonectria parasitica) – A fungal disease affecting chestnut trees, causing cankers on the trunk and branches.

Treatment: Chestnut trees with blight cankers can be treated and often cured with mud packs applied to each canker.

6. Black Knot (Dibotryon morbosum) – A fungal disease that affects cherry and plum trees, causing black, warty growths on the branches.

Tree diseases cause severe damage to branches foliage and fruit like black knot

Treatment: Black knot can be controlled by removing all knots and swellings by pruning 3 to 4 inches below the knot during the dormant season. Where infections occur on larger branches, excise infected tissue down to healthy wood.

7. Cedar Apple Rust (Gymnosporangium juniperi-virginianae) – A fungal disease affecting apple trees but is spread by cedar trees.

Treatment: Fungicides with Myclobutanil are most effective in preventing rust. Spray trees when buds first emerge until spring weather becomes consistently warm and dry.

Tip: Fungicides are only effective when applied before leaf spots or fruit infections appear.

8. Fire Blight (Erwinia amylovora) – A bacterial disease affecting apple and pear trees, causing wilting and blackening of the branches. There is no cure for fire blight, only control.

Treatment: Once an infected tree is removed, the fire blight bacteria are also removed. You can safely plant another apple or pear tree in its place (choose a fire blight-resistant variety).

9. Verticillium Wilt (Verticillium dahliae and Verticillium albo-atrum) – A fungal disease that affects a wide range of trees and causes foliage chlorosis and wilting. There is no effective treatment for verticillium wilt.

Tree diseases cause severe damage to branches foliage and fruit like verticillium wilt

Treatment: Prune out affected branches and dispose of them immediately. Do not use infected wood for chips for landscape mulch.

Tip: Sanitize all pruning equipment before moving to another tree to prevent the spreading of the disease.

10. Sudden Oak Death (SOD) (Phytophthora ramorum) – A fungal disease affecting oak trees, causing leaf spots, cankers, and rapid death.

Treatment: Reliant Systemic Fungicide is a phosphonate compound injected into the tree or mixed with a surfactant and sprayed on the trunk for absorption through its bark.

Note: This treatment is not a cure but can help protect trees from infection and effectively suppress disease progression in early infection stages.

Tree Diseases

In this article, you discovered information to help you identify and treat several tree diseases before they cause your tree’s rapid decline or death.

Knowing how to identify when your tree is diseased will help you spring into action with effective treatments or get professional help.

Your inability to detect or identify when your tree is diseased can lead to rapid decline, death, and catastrophic personal or structural damage when it collapses or falls on your property.

Sources:
extension.umn.edu/plant-diseases/dutch-elm-disease
dec.ny.gov/docs/lands_forests_pdf/oakwiltusda.pdf
portal.ct.gov/CAES/Fact-Sheets/Plant-Pathology/Protecting-Chestnut-Trees-from-Blight
extension.umaine.edu/ipm/ipddl/publications/5091e/
fs.usda.gov/wildflowers/plant-of-the-week/gymnosporangium_juniperi-virginianae.shtml
ipm.ucanr.edu/PMG/PESTNOTES/pn7414.html
invasivespeciesinfo.gov/terrestrial/pathogens-and-diseases/sudden-oak-death

Image credit: mndaily.com
Image credit: web.extension.illinois.edu
Image credit: hortnews.extension.iastate.edu


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Preventing Fire Blight Tree Disease

What is Fire Blight Tree Disease?

Fire blight is a hard to control disease of fruit trees like pear and apple. It is caused by bacteria, its effects are devastating and it leaves a behind a burnt appearance; this is where it gets its name from. In addition to fruit trees, it attacks ornamental plants like roses, cotoneaster crabapple, loquat, hawthorn, pyracantha, and mountain ash. Unlike dieback, fire blight attacks flowers first, twigs next and finally branches.

Signs of this Disease

The first signs of fire blight usually appear in early spring, when the weather is humid and rainy and when temperatures rise above sixty degrees. Flowers infected by the disease turn black and die. The disease moves through the branch, infecting and killing young twigs. These dead twigs go black and curl over like a shepherd’s hook.” Affected branches look fire scorched as their leaves are black and wilted. Cankers, which are slightly sunken areas show up on the branches and the trunk. Fire blight affects many parts of the plant including leaves, stems, fruits and blossoms. In wet spring weather, a translucent milk-like, sticky liquid that contains multitudes of bacteria oozes out of the infected part of plant.

Fire blight spreads effortlessly in a lot of different ways and through different means, they include:

• Insects, birds, and animals transmit it from one plant to another.
• Rain drops splashes the bacteria among plants.
• Plants make contact all the time, that way the bacteria can move from an infected plant to an uninfected plant.
• Gardening tools can transmit the disease when gardening or even when watering. Tools should be sterilized after use on an infected plant.

Late spring or early summer is the maximum time of risk of infection. At this time, the bacterial emerges from its dormant period and the cankers become more pronounced. Infected branches should never be left on the ground when pruned, they should be immediately burnt or put in a bin as placing them on the ground could infect the surrounding bushes or trees.

Commonly Affected Plants

In your home garden, fire blight can be very damaging to pear and apple trees especially pear trees as they are very susceptible. Some pear trees, (e.g. Bradford) are unaffected by the disease but can develop it when the environment is advantageous to disease development. Some plants in the rose family such as the Rosacea, can be infected with fire blight, others include; mountain ash, photinia, crabapple, hawthorn, loquat, pyracantha, spirea, cotoneaster and quince.

Prevention & Treatment

Fire blight has no cure thereby making prevention very important. Though there are many ways to control fire blight, these methods are not 100% effective. Some fire blight control methods include; making use of recommended sanitation measures and cultural practices, choosing tolerant varieties, and applying bactericides and insecticides.

Bactericides & Insecticides: Bacteria enters plants through fresh wounds, blossoms or natural openings, it is then spread by rain and insects such as ants, bees, aphids, beetles and flies who transfer the bacteria to blossoms. Insect control can decrease the spread of bacteria, however, insecticides shouldn’t be used when plants are blooming. To learn more about disease and pest prevention oils, visit: 72tree.com/using-dormant-horticultural-oil-treat-tree-insect-infestations/

Sanitation Measures & Cultural Practices: all infected plant parts should be removed and destroyed, and all pruning tools should be disinfected with household bleach and water (one part bleach and nine parts water). This will lead to a reduction in the spread of the disease. Cuts should be made at least 8 to 12 inches beneath the infected tissue.

Pears: Pear trees can be treated with a copper fungicide spray (pre-bloom) and a streptomycin spray in bloom. The first spray should be applied immediately the flowers open and should be repeated every three to four days. There should be a minimum of fifty days between the application of streptomycin and harvesting of fruits.

Apples: If fire blight was severe the year before, then copper fungicide should be sprayed just before bloom. All branches and spurs should be thoroughly covered with streptomycin spray which is the recommended bactericide for apple trees in bloom. It should be sprayed first at the beginning of bloom and should be repeated every three to four daysas long as there are flowers.

Crabapple: copper fungicides are also used to treat crabapple trees. In other to lessen bacterial inoculum on the exterior of twigs and spurs, they should be applied before and after bloom. It shouldn’t be applied when plants are blooming as it may cause fruit abortion or russeting on the plant.

Arborists Discuss Controlling Tree Disease

Scheduling an annual inspection of your landscape is another way to prevent and treat tree disease. When you detect that something has gone awry with your trees and plants, contact your local tree professional. Properly identifying and treating the issue is key to halting it and preventing future occurrences.

Sources:
http://www.clemson.edu/extension/hgic/pests/plant_pests/veg_fruit/hgic2208.html
https://www.extension.purdue.edu/extmedia/BP/BP-30-W.pdf