I was looking in my backyard one day only to find my tree was changing color, it’s turning black. Concerned for my tree’s health, and maybe a bit more my house (since it is in falling distance) I did some research.
Trees turn black due to various diseases depending on the tree. Some common diseases that may cause your tree to turn black include Gloomy Scale, Verticillium fungus, Fire Blight, Bacterial Cankers, Sooty Mold, Black Knot, or Bacterial Wetwood.
Identifying which disease your tree has depends both on the tree species and the varying symptoms. Lets look at all the possibilities of what might be happening to your tree and then dive into how we might narrow it down.
Tree Diseases That Turn It Black
There are so many possibilities, but lets narrow them down by the type of tree and the main symptoms.
| Disease | Common climates | Common Trees Affected | Other Common Symptoms |
| Gloomy Scale | Southeastern US, mild and wet climates | Elm, Maple, Poplar | branch dieback, thinning canopy, darkened bark, and bumpy texture |
| Verticillium Wilt | Numerous, especially bad in temperate climates | Ash, Magnolia, Maple | sudden wilting, brown spots around leaf margins, beneath bark will turn green and grow black streaks |
| Bacterial Cankers | Generally Northern climates, however can grow in the many | Localized to different Species of Maple tree | affects already weakened trees as a secondary infections, black pustules grow and eventually form solid black layer on bark |
| Black Knot | Variety of Climates | Cherry, Plum, and other Prunus trees | large black swollen bark that may be cracked and ooze sticky liquid |
| Fire Blight | Warm temperate climates | Apple, Crabapple, and other Prunus trees | tree shoots or flowers turn black, branches bend to a crook and often grow dark and crack |
| Sooty Mold | Warm dry climates | Boxelder, Elm, Maples | blackened bark and powdery material that may spread to other surfaces off the tree |
| Bacterial Wetwood | Warm wet climates | Aspen, Elm, Willow, and many others | oozing dark liquid from within tree, insects generally attracted due to alcoholic smell from liquid |
Now this is by no means a comprehensive list of all diseases that could be causing your tree to turn black, but it does provide for the most common. If you need help identifying each one click on the name of the disease and it will open an image in another tab to help.
If your shrubs or lawn are the plants that are struggling, click on the links to find out if what may be causing harm to your shrubs or grass.
How To Keep Your Tree From Dying
When it comes to treating each of these diseases below you will find quick ways to help either reduce the spread of the disease or eliminate the diseased area to stop it from spreading.
Gloomy Scale:
- Commonly mistaken for a fungus, gloomy scale is an insect infestation
- Using a pressure washer on an early infestation can help
- Horticulture oils can be applied during dormant months
- Insecticides are most effective during the early spring months as the dormant insects are also emerging(this may also kill natural enemies)
Verticillium Wilt:
- Fungus that grows on both the leaves and branches
- Prune off infected limbs at least 8 inches before infection
- Bury or Burn the infected parts
Bacterial Cankers:
- Keeping the tree healthy is the best defense because this fungus, it takes advantage of already weakened trees
- Prune off infected limbs at least 8 inches before infection
- Bury or Burn the infected parts
- Non-toxic fungicides may help
Black Knot:
- Prune infected branches at least 8 inches before the knot
- Completely remove large branches with established knots
- Chisel away knots on the trunk with a 1 inch perimeter
- Don’t allow infected parts to fall to the ground
- Dispose of infected parts by burying a distance away or burning
- Fungicides can offer protection whether natural or synthetic
Sooty Mold:
- Mold that grows on the excretions of insects that feed on trees
- Can be treated with insecticides, however there are natural ways
- In spring you can spray the branches with a horticultural oil spray (this removes some overwintering insects)
- As leaves grow spray the tree with strong jets of water to remove aphids from the leaves(must be done on a weekly basis)
- If this does not work use a non-toxic insecticide
Fire Blight:
- Bacterial infection that may spread with splashing water
- Prune off infected limbs at least 8 inches before infection
- Burn the infected parts or place in bags to dispose
Bacterial Wetwood:
- No effective methods exist to eliminate wetwood
- Although recommended in the past, do not drill holes as this will introduce bacteria further into the tree
- If it is affected just below the bark, cut away the bark to allow for wound closure
- A surface treatment can be to mix a ratio of 1/9 bleach and water to apply to the surface
- If covering a significant part of the tree(50% or more) it can significantly weaken the structural integrity and a professional should be consulted to potential cut it down.
None of these solutions can be considered a guarantee to eliminate these tree diseases or infestations. Often pruning the tree effectively can eliminate the infected or dead parts increasing the health of the tree. Ensure that all of the pruning occurs during the winter months as this is the healthiest time due to the tree being dormant.
Moss is another pest that plagues many lawns and can consume all of the nutrients your lawn needs to grow. Take a look at our article about keeping deadly moss off of your lawn.
After pruning ensure to clean the tools with a solution of water and bleach followed by oiling the tools. The bleach will clean it of any surviving fungi or bacteria and the oil will help your tools last longer and work better.
Be careful when choosing chemicals to use as many are potentially harmful to the tree, insects that are good for the trees growth, or to you. Copper based fungicides perform the best in most cases when compared to other brand name fungicides. Ultimately if you are concerned for the health of the tree or the structural integrity you should contact a professional arborist that can tell you more. It is increasingly common to be able to take a picture and rapidly have an excellent consult on how to proceed.
How To Know If Your Tree Is Dead
It can be very important to recognize if your tree is dead or already has one foot in the grave. If it’s close to your home or any place that you frequent it is just waiting for the right time to invite itself into your home. Below are some signs from the roots to the branches to help you determine this before it is too late.
From the Roots:
- The tree has decaying roots near the surface
- The tree has developed a significant lean
- Fungus or insects have made their home near the base of the tree
To the Trunk:
- Missing significant portions of bark
- Fungus or Cankers populating along the trunk
- When scratching the tree if it is easy to reach the inner layers of bark and it is brownish color
- Cracks moving vertically up the tree
Ending with the Branches:
- Absent leaves during the budding season
- Dead leaves and branches holding onto those dead leaves
- Fungus or Cankers emerging along leafless branches
When To Call A Pro
When it comes down to it, ask yourself if this tree falls in the worst possible place would it cause financial damage or worse, physical to you or anyone? If you answered yes then please do not hesitate to call a professional immediately.
Early action can solve a lot of problems, so every once and a while when you are walking in your yard take a closer look at your trees for a moment. These remedies sometimes take a long time and simple, consistent application can save you from spending lots on a professional solution for a big problem. Keeping these from spreading can decrease the likelihood of another offender.
BONUS
If you want to know what type of tree you have consider downloading this APP made by Virginia Tech for identifying. With a few questions it can nail it most of the time.