Ash Tree Disease

There are many types of ash trees. Ash trees are a common tree species found in many parts of the world. They are prized for their beauty and can grow to be quite large. In recent years, ash tree disease has been a growing concern for tree owners and managers. 

There are a few different types of ash tree disease, all of which can cause serious damage to trees, and most of which are caused by fungi. If you have an ash tree on your property, it is important to be aware of the infections, symptoms, and treatment options for these diseases.

 

General signs of infections to watch out for in ash trees are:

 

Common ash tree infections are :

  • Anthracnose
  • Verticillium Wilt
  • Emerald Ash Borer
  • ash rust
  • Powdery mildew
  • decays and cankers
  • Ash dieback
  • Mycosphaerella leaf spot
  • Ash flower gall 
  • Sooty mold
  • Cotton root rot
  • Ash Cold Injury

Anthracnose

One common type of ash tree disease is called Anthracnose. This disease causes lesions or spots on leaves, branches, and stems. The lesions can be black, brown, or gray in color, and they often have a fuzzy appearance.

Early signs of anthracnose include wilting leaves and small dead branches. As the disease progresses, larger branches may die off completely.

There is no cure for anthracnose infection, but trees can be treated with fungicide to help slow the spread of the disease.

Verticillium wilt

Verticillium wilt is another common ash tree disease. This disease is caused by a fungus that invades the tree through the roots and spreads up into the trunk. Symptoms of verticillium wilt include yellowing or wilting leaves, branch die-back, and premature fall coloration. The fungus can cause trees to slowly decline over several years, eventually leading to death.

There is no treatment for trees infected with verticillium wilt, but trees can be treated with fungicide to help prevent the spread of the disease.

Emerald Ash Borer (EAB) infestation

Ash trees are also susceptible to Emerald Ash Borer (EAB) infestation. EAB is a destructive beetle that attacks ash trees and feeds on their inner bark. This feeding disrupts the tree’s ability to transport water and nutrients, which can lead to die-back and death.

EAB infestation is difficult to detect until trees have already been damaged, so it is important to be aware of the signs of this pest. Signs of EAB infestation include D-shaped holes in the bark, thinning branches, and premature fall coloration.

Ash rust

Ash rust is a fungal disease that affects ash trees. This disease causes red or orange spots on leaves and can lead to defoliation and tree death. There is no cure for ash rust, but trees can be treated with fungicide to help prevent the spread of the disease.

Powdery mildew

Powdery mildew is another type of tree disease. This disease is caused by a fungus that invades the tree through the leaves and branches.

Symptoms of powdery mildew include white or grayish-white spots on leaves, stunted growth, and leaf curling. Powdery mildew can cause trees to slowly decline over time, eventually leading to death.

There is no treatment for trees infected with powdery mildew, but trees can be treated with fungicide to help prevent the spread of the disease.

Decays and cankers

Decays and cankers are two other common diseases that affect ash trees.

Canker Disease (caused by the fungus Neonectria ditissima) is one of the more serious diseases that affects ash trees. It begins as a small, orange canker on a twig or branch. As time goes on, the canker will become larger and encircle the branch, eventually killing it. If the disease is not treated, it can eventually kill the entire tree.

Decays are caused by a variety of different fungi, and cankers are caused by bacteria. These diseases cause lesions or spots on branches and stems, and can lead to branch die-back and tree death.

There is no cure for decays or cankers, but trees can be treated with fungicide or antibiotics to help prevent the spread of the disease.

Ash dieback

Ash dieback is a disease that affects ash trees. This disease is caused by a fungus that invades the tree through the roots and spreads up into the trunk.

Symptoms of ash dieback include yellowing or wilting leaves, branch die-back, and premature fall coloration. The fungus can cause trees to slowly decline over several years, eventually leading to death. There is no treatment for trees infected with ash dieback, but trees can be treated with fungicide to help prevent the spread of the disease.

Mycosphaerella leaf spot

Mycosphaerella leaf spot is another type of ash tree disease. This disease is caused by a fungus that invades the tree through the leaves and branches.

Symptoms of mycosphaerella leaf spot include small, dark spots on leaves, premature fall coloration, and leaf curling. Mycosphaerella leaf spot can cause trees to slowly decline over time, eventually leading to death.

There is no treatment for trees infected with mycosphaerella leaf spot, but trees can be treated with fungicide to help prevent the spread of the disease.

Ash flower gall 

Ash flower gall is a fungal disease that affects ash trees. This disease causes galls (or swellings) to form on the flowers and can lead to defoliation and tree death.

There is no cure for ash flower gall, but trees can be treated with fungicide to help prevent the spread of the disease.

Sooty mold

Sooty mold is a fungus that grows on the honeydew excreted by aphids, scales, and other sap-feeding insects. Sooty mold blackens leaves and branches, reducing their photosynthetic ability and causing die-back.

There is no treatment for sooty mold, but trees can be treated with insecticides to help control the sap-feeding insects that cause the mold to grow.

Cotton root rot

Cotton root rot is a fungal disease that affects ash trees. This disease causes the roots of trees to rot and can lead to tree death.

There is no cure for cotton root rot, but trees can be treated with fungicide to help prevent the spread of the disease.

Ash Cold Injury

Ash cold injury is a condition that affects ash trees. This condition is caused by the freezing of leaves, buds, and branches in winter weather.

Symptoms of ash cold injury include wilting leaves, stunted growth, and dead branches. Ash cold injury can cause trees to slowly decline over time, eventually leading to death.

 

General causes of ash tree infections are:

  • Fungi, insects, and bacteria
  • Environmental conditions, such as drought or flooding
  • Poor tree health
  • Girding injury also makes trees susceptible to infection, as it restricts the flow of water, nutrients and sugars in the trunk and branches.
  • Herbicide injury is also a common cause of ash tree infections. Symptoms include twisted, cupped, curled or stunted leaves; defoliation and so on
 

Pre-emptive measures to protect ash trees from diseases

As with any plant disease, prevention is always better than cure. There are several things you can do to help protect your ash trees from infection. These are a few things you can do to help protect ash trees from disease:

  • Water trees regularly during dry periods
  • Avoid wounding trees
  • Remove dead or dying trees
  • Treat trees with fungicide or insecticide as needed

By following these simple steps, you can help protect your ash trees from disease and maintain their health and beauty for years to come.

 

General problems encountered while protecting ash trees are:

  • Cost of treatment
  • The negative effects of chemicals on trees and environment
  • Time commitment needed to properly care for trees.
  • Ash trees are not excellent candidates for fungicide. 
 

Ash pest

Trees pests play a major role in infection of ash trees, the common ash tree pest are:

  • Aphids are small, sap-sucking insects that can be found on the leaves and branches of trees.
  • Caterpillars are the larval stage of butterflies and moths. They can be found feeding on the leaves of trees, often skeletonizing them.
  • Emerald ash borers are small, green beetles that can be found tunneling in the bark of ash trees. They are responsible for the majority of cases of ash tree death. Emerald ash borers are a highly destructive wood-boring insect pest. 
  • Japanese beetles are a common pest in the United States. They are a small, brown beetle that feeds on the leaves and flowers of trees.
  • Ash plant bugs are small, red bugs that can be found feeding on the leaves of ash trees. They damage the leaves by sucking the sap out of them.

Treatment for trees infected with aphids, caterpillars, or scale insects includes spraying the tree with insecticide.

Treatment for trees infected with Emerald ash borer or Japanese beetle includes spraying the tree with insecticide and removing infested branches.

 

Conclusion

There are several diseases that can affect ash trees, but the most common are ash dieback, mycosphaerella leaf spot, and ash flower gall. These diseases are caused by fungi, insects, or bacteria and can lead to branch die-back and tree death.

The best way to prevent these diseases is to water trees regularly during dry periods, avoid wounding trees, remove dead or dying trees, and treat trees with fungicide or insecticide as needed. 

Trees pests play a major role in infection of ash trees; the most common pests are aphids, caterpillars, Emerald ash borer, Japanese beetle. Treatment for trees infected with pests includes spraying the tree with insecticide.