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The two most common ash trees in NJ are the white ash (Fraxinus Americana), and the green ash (Fraxinus pennsylvanica), these both grow to a height of between 50 and 80 feet tall and are similar in shape. They require moist well-drained soil, such as near a body of water like a lake or river. Ash trees can live to be between 175 and 200 years old, if not plagued by disease.

Ash trees are beneficial for several reasons:

  • Valued for its strength and elasticity ash wood is used to make baseball bats, bows, drums and electric guitars.
  • Its foliage and seeds feed animals as well as butterfly and moth caterpillars.
  • Ash tree wood is used as firewood and for smoking food, especially meat.
  • The ash tree has compound leaves. Between 8 to 15 inches long and consist of 5 to 13 oval serrated leaflets. Leaves are green during the spring, and turn yellow, orange, red and purple in the fall.
  • Both domestic animals, cows and goats and wild animals like rabbits eat the leaves and branches of ash tree.

While the ash tree is favored by landscapers because of its full canopy of interesting leaves, and whitish bark; there are several diseases and a pest that can be fatal to the ash tree in some cases, and treatable in others.

Fungal leaf diseases are common during the spring with heavy rains. Many of these fungi cause abnormalities in the plants they infect. Despite the ragged appearance of infected plants, most of the leaf spot diseases have little impact on overall plant health. The diseases that hurt the plan the least, besides being unsightly, are the easiest problems to control with fungicide applications. Treatments must be done at bud break and repeated during the cool and moist days of spring, good coverage is essential.

Ash Rust

Ash rust is common in New Jersey landscapes when weather conditions are favorable. A wet and stormy spring season promotes the development and spread of the fungus. Fungicides are usually not necessary; however, for a valued tree they can be used. It is caused by the fungus Puccinia sparganioides, which affects white and green ash. It is a heteroecious rust, meaning that it requires more than one host plant to grow and reproduce. In this case, the alternate host is salt marsh or cord grass, and they are the overwintering plants for this disease.

Symptoms on ash are very distinct.

In the spring - Fungal spores are carried by the wind from the salt marsh or cordgrass to the ash foliage, and yellow spots quickly form on top of the leaves as well as stems and leaf petioles, the leaf attachment to stem.

A few weeks later - The fungus will produce bright-orange infection cups, which contain the spores on the petiole, stem, and lower surface of the leaf.

In early summer - The leaves become distorted and begin to die, giving the tree a torched appearance. The stems and petioles can develop wartlike swellings with the spores and cause dieback.

 The spores are then windborne and reinfect the salt marsh or cordgrass and the cycle starts over once again, preparing for infection again next spring.

Younger trees are more negatively affected than established trees. Corrective pruning and branch removal is required to encourage new growth and reduce infection sites for other diseases and insects. When fungicides are used, they must be applied at bud-break in early spring and repeated at intervals to achieve adequate control. Despite the dramatic appearance of this disease, the overall impact on plant health is minimal. Infected leaves stay on the tree, so despite the necrotic tissue, there is enough green tissue to produce adequate carbohydrate reserves to sustain the plants for the season.

This fungus is rarely destructive, it can, however, kill young trees. Premature defoliation can occur with severe infections. If trees are infected with ash leaf rust for several years, trees can become weakened and are more susceptible to winter damage and branch dieback. Getting rid of the alternate hosts, marsh grass and cordgrass, can be effective also. Calling the professionals at Advanced Tree Care to assess your trees will help with this disease.

Ash Yellows

Ash yellow is a slow killer and there is no cure. Ash yellows affect both white and green ash trees. It is caused by a microorganism called Candidatus fraxinii and affects the tree's vascular system. It can be spread through the soil or carried by insects like leafhoppers. A leafhopper is a common name for tiny insects that drink sap from a tree or shrub.

  • In the early stages this disease can be treated by pruning affected branches and spraying with a fungicide.
  • The leaves turn pale green or yellow before falling off, and the branches die over the winter.
  • A susceptible tree can die within 1 to 3 years.

The tree will need plenty of fertilization to have the nutrition to fend off this disease. If more than 50 percent of the foliage is affected by dieback which is characterized by progressive death of twigs, branches, shoots, or roots, starting at the tips; the tree needs to be cut down to prevent the disease from spreading.

Ash yellow is a slow killer and there is no cure. Ash yellows affect both white and green ash trees. It is caused by a microorganism called Candidatus fraxinii and affects the tree's vascular system. It can be spread through the soil or carried by insects like leafhoppers. A leafhopper is a common name for tiny insects that drink sap from a tree or shrub.

  • In the early stages, this disease can be treated by pruning affected branches and spraying with a fungicide.
  • The leaves turn pale green or yellow before falling off, and the branches die over the winter.
  • A susceptible tree can die within 1 to 3 years.

The tree will need plenty of fertilization to have the nutrition to fend off this disease. If more than 50 percent of the foliage is affected by dieback which is characterized by progressive death of twigs, branches, shoots, or roots, starting at the tips; the tree needs to be cut down to prevent the disease from spreading.

Verticillium Wilt and Ash Anthracnose

These two fungal diseases can produce wilting, dieback, and other symptoms like EAB infestation and ash yellows, and can be just as deadly. Verticillium wilt causes gradual foliage die-back and eventual death, and it is incurable once it has entered the tree. Ash anthracnose also affects the leaves, giving them purple and brown spots and forcing them to drop prematurely.

Fungal diseases can be controlled in the early stage by pruning affected branches and fertilizing the soil with a low-nitrogen, high-phosphorous blend to ensure the tree has the nutrient it needs to fight the diseases off. Once an ash tree has lost half of its foliage, it should be cut down to avoid infecting other trees.

Calling the experts at Advanced Tree Care when you see your ash trees in any distress is the first step in helping your trees to remain healthy.