A beautiful family of trees, the sycamores (Platinus sp.) stand tall and large, but they are still prone to many diseases that can result in a weakened tree or total tree death.
Knowing the signs and common causes of an infected tree is the most important part of diagnosing and preventing any further infection.
Use the list below to help identify and stop any disease before it is too late!
Gnomonia leptostyla is the fungus that causes anthracnose in sycamore trees. It spreads in the spring through insects, heavy rain, and water splash.
The main symptoms will be shown in the tree’s characteristics resulting in twisted branches, leaf dieback, and blight.
It may also be noticed that the young branches have sunken cankers while the leaves will exhibit black and brown legions.
While anthracnose is usually not fatal on its own, it can weaken the tree, leaving it susceptible to insects and other diseases.
Keeping the tree healthy is your best bet at preventing any diseases or pests.
2. Canker Stain
Canker stain comes from infection caused by the fungus Ceratocystis fimbriata. It is mainly spread by humans while performing pruning and maintenance on the trees.
Dwarfed leaves should lead to a discovery of a black or brown stain on the trunk.
These will grow longitudinally up the tree trunk reaching 20 to 40 inches in length but rarely growing to more than 2 inches in width.
Wood will turn rust-colored and blue or black near the sites of the canker.
Disinfecting pruning tools is the best way to prevent this disease. Without human interaction, this disease would not spread as prolifically.
Preventing wounds on the tree helps to reduce the open wood that can become infected. Unfortunately, this disease usually results in complete tree dieback if the canker circles the tree or overtakes it.
3. Powdery Mildew
Powdery mildew is extremely common and looks like white dust coating the leaves of the plant.
Caused by fungal spores that thrive in moist warm environments, it can prevent the leaves from being able to photosynthesize.
Look for small white dots of mildew that begin to grow on either side of the leaf’s surface. It will start as small white dots and spread to cover the entire leaf.
When the leaf is shaken, it will release white spores that look like dust.
Preventing this can be difficult because most of the time it occurs because of the natural environment. To help mitigate it, avoid getting the leaves wet, and increase air circulation as much as possible.
While powdery mildew will prevent the tree from photosynthesizing, the tree will most likely recover, especially if it is deciduous.
4. Bacterial Leaf Scorch
Usually occurring in summer, the leaves will catch one of many bacteria spread by a small leafhopper as it feeds on the leaves.
Summer is the time of greatest infection because the larva of the leafhoppers hatch and begin to feed.
Bacterial leaf scorch begins with the leaves turning an olive green and then transitioning to black and crispy light brown.
The older leaves are affected first, spreading to the younger growth as it begins to thrive.
Pruning off affected areas will not cure the tree of the symptoms because it is caused by leafhoppers. Rather, it should be remedied using pesticides or trunk flare injections.
Reducing the population of leafhoppers is the best way to prevent the spread. The tree will most likely recover once the insect population dies down and the leaves drop.
5. Leaf Spot
Spread by a few types of fungi, this disease spreads via wind and can affect new and old growth. Infection occurs anywhere the fungal spores touch the leaf surface.
Purple or black spots will form where the spores have touched the leaf. Over time, the leaf will die beginning at the point of infection, first turning brown before eventually spreading to kill the entire leaf.
Leaf spot is a minor fungal disease and can be controlled with a common fungal spray. Be sure to continue to spray the plant regularly according to the product directions for an effective cure.
Large trees are difficult to treat this way, but luckily, most trees will recover from this when they drop their leaves in the fall.
The fungus Cephalosporium diospyri causes dieback in large sycamores. Wilt is spread by wind, but it can also live in moist soil conditions.
In most cases, the initial infection begins in a small wound that was created by an outside force.
Young shoots will begin to brown and curl. Along with yellowing leaves, defoliation, the blight of new growth, and the browning of leaves are all common indications of wilt.
Wilt has the same symptoms as many other issues, so it can be difficult to identify in the beginning.
The spores can survive in the soil for extended periods of time, so wilt may last long enough in the soil to infect the tree seasonally, eventually weakening it to a point of dying.
7. Botryodiplodia Canker
Botryodiplodia theobromae spores are transferred by rain and wind and are the most abundant in the spring.
Try to do any necessary pruning in the winter to reduce the spread of fungal spores that are able to be released.
When examining the tree, you may notice small black fruiting bodies that are about the size of an eraser or smaller on the dead or dying wood.
Discolored bark that shows signs of cracking is another tell-tale sign of an infected tree.
Anytime a tree has open wounds, it is more susceptible to diseases. Since this virus infects open wood, try not to leave large wounds on the tree.
Cankers are usually fatal, but pruning off parts of the tree with a canker can help reduce it from spreading.
8. Shoestring Root Rot
A tree showing signs of Armillaria root rot can be a good indicator the tree has already begun to die. This fungus spreads through the soil and thrives in moist environments.
Examine the trunk of the tree for rotting and decaying wood. White mushrooms will form sporadically and turn the infected wood white while thin black lines will begin to form and spread through the decaying wood.
The best way to help the situation is to reduce moisture levels and keep the tree from other stresses as trees are thought to become infected when weak and affected by multiple stressors.
In most cases, the trees will fully succumb to the fungus as more of the wood begins to rot.
9. Cotton Root Rot
Phymatotrichum omnivorum most commonly affects cotton crops, surviving in soil for multiple years. This fungus will invade the roots and begin to feed on the tissue.
Full plants will die quickly as the base of the stem and roots begin to rot, cutting off the plant’s nutrient supply.
The tree will begin showing signs that resemble underwatering, wilting, and weakness. The tree will also lack vigor, have black rotting tissue, and display a poor appearance.
Examine the roots for rot or black spots to know for sure.
Avoid wet anoxic growing conditions. Cotton root rot thrives in moist environments and spreads quickly through the soil and water splashing.
Plant resistant species if the tree is removed since the fungus will affect other plants for years to come.
10. Trunk Rot
Trunk rot is mainly found in wet environments where the soil never dries out. Many fungi will begin to thrive in rotting dead and moist wood.
Any sign of fungal bodies growing from the wood is a sign of rotting wood in the trunk or branches, especially if there is an overall lack of vigor in the plant’s growth and habit or if its leaves begin to yellow and brown.
If fungal bodies begin to grow where they can flourish, they may spread to any dead wood on the living tree.
If you notice rot forming on a branch, remove it to stop the spread, and destroy any infected materials.
Trunk rot can lead to full tree death as it will cause the connection from the nutrient-producing roots to be severed.
11. Sooty Blotch
Infection by the fungus Gloeodes pomigena makes it look like there has been a fire nearby that burned part of the tree right through the bark.
Sooty blotch spreads by wind and rain, infecting the open wounds of the tree.
Appearing as black spots on the trunk and branches, the affected areas range from a few inches to a few feet long. It will look like charred wood under the bark in areas where the bark has fallen away.
Be sure to remove any infection you identify to prevent it from spreading to other trees nearby. It thrives in hot and drought conditions, so try to ensure trees receive ample water through irrigation.
In most cases, the tree will begin to die, and sadly, this disease is untreatable.
Diseases can take out an established tree if unmanaged. Always look for these important signs of infection to get a jump on treating the problem however you can!
In many cases, a tree will fight off infection to the point of death, but sometimes it is best to remove the tree to prevent further infection and loss of more landscaping trees.