Common Tree Pests & Diseases In Minnesota

For property owners, trees and plants add beauty and value. However, when care is not taken, diseases can take root; causing decay and other health problems leading to death and destruction. Property owners should hire an I.S.A certified arborist to conduct a thorough examination of all trees and plants on their property on an annual basis.

Tree diseases can affect the health of your trees and shrubs in a variety of ways, and therefore necessitate different types of treatment. Each genus and tree species are susceptible, to varying degrees, to different insects or tree diseases. As a property owner, you want to keep your eyes open for a few common symptoms, such as leaf spots, powdery mildew appearing on the leaf surfaces and leaves turning yellow out of season.

If any of the above symptoms present themselves, it can be a sign that an insect or disease could be affecting your trees.  Property owners should take action and call a local tree and plant health care specialist, such as Birch Tree Care. Birch Tree Care knows all the pests and diseases affecting Minnesota and operates in St Paul's, Minneapolis and the surrounding metro area.

The most common insect in Minnesota is the EAB, and the most common tree disease is the Dutch Elm disease.  The fungus causing Dutch Elm Disease prevails as the most widely spread, with the spread of infection being caused by beetles and root grafting.

Dutch Elm Disease (DED)

Some tree diseases are serious and damaging in their effects. Dutch elm disease falls into this category. As professionals and experts in the field, the severity of this threat cannot be understated.

In the early 20th century, a strain of the fungus arose and the destruction of elm trees started. Data shows that almost all of the United States, and all of Minnesota, falls within the area of infection.  In the past few decades, the vast majority of mature European elms or American elms have succumbed to the Dutch Elm disease. This fungal disease has resulted in the death of millions of elm trees across the United States.

Dutch elm disease is a pervasive tree disease is caused by the fungi ophiostoma ulmi and novo ulmi. The destructive fungi infect tree roots but cause tree death by affecting the trees vascular system.

In a tree, it is the xylem and phloem tissue that deliver water and nutrients to the rest of the plant.  In simple terms, xylem and phloem make up the "transport system" for water and nutrients in a tree.

In an attempt to block the fungus from spreading farther, the tree reacts by plugging its xylem tissue with gum and tyloses. What this means is that the tree has "cut itself off" from a critical part of the transport system for nutrients and water.

By creating "plugs" to prevent the spread of the virus, the tree buys itself more time but ultimately dies.  Eventually, starvation kills the tree. Symptoms of Dutch Elm disease usually starts with the wilting, yellowing and shrivelling of the elm leaves.

Dutch Elm disease poses an invasive threat to properties because the disease spreads easily by the bark beetle, scolytus multistriatus. This particular beetle is known more commonly as the European Elm Bark beetle, Elm Bark beetle. The beetle is difficult to detect and lives within an infected host tree. Through feeding, the Elm Bark beetle transfers the fungal disease to healthy trees, compromising them as well.

The solution to Dutch Elm disease requires more than a simple pruning: it necessitates certified arborists. Certified arborists should be consulted to provide a management plan for properties with salvageable elm trees.

The most effective solution is for the entire tree to be cut down or removed. The elm wood should then be burned, chipped or buried.  The stump of the dead infected tree must be handled in one of two ways: it must be debarked or removed.

If a property owner chooses to have the infected stump debarked, it must be done to the existing grade. Debarking is necessary because it minimizes the environment suitable for bark beetle feeding and mating.

If a property owner chooses to have the infected stump removed, it should be done through professional digging and grinding. If the stump is nether debarked or removed, this can cause the disease to spread.

Other trees on the property need to be treated or removed. This is required to prevent a second wave of the disease outbreak, caused by beetle feeding or root graft infection.  Birch Tree Care can confidently advise you as to the best and most affordable way to mitigate infection.

For high-value elm trees, like large legacy trees, you should act quickly to try and preserve these trees.  It is best to treat trees preventatively before signs and symptoms present themselves. However, for those who do not treat preventatively, getting treatment at the earliest sign of symptoms is vital. Fungicides must be injected into trees infected by Dutch Elm disease, and those at risk of infection.

Fungicide injections prevent the movement of the fungi into parts of the tree (or trees) that are not yet colonized. Using fungicides to treat Dutch elm disease is important in symptomatic and non-symptomatic trees. Within the industry, several different fungicides have been used but all are relatively expensive and none are completely effective.

Birch Tree Care specialists have extensive experience with best in class certifications for fungicide application. Our professional experience means that you can be sure that your trees receive the best treatment and protection.

Emerald Ash Borer (EAB)

The Emerald Ash Borer (EAB)  is a sophisticated killer: it leaves no hint of death until later when it has moved onto its next victim. This invasive insect has infected much of North America and was confirmed in Minnesota in 2009.  This invasive species has killed tens of millions of ash trees across the United States.

The Emerald Ash borer, agrilus planipennis, is an invasive insect that destroys ash trees. Adult beetles lay eggs on the bark of ash trees, and once hatched into larvae, they move under the bark and feed on the tissues of the tree. The tissue the larvae feed on transports water and nutrients from the roots to the rest of the tree. It is the destruction of this critical tree tissue that causes the ash tree to die over time.

Examining trees for the presence of the Emerald Ash Borer is used as the most common method to detect the pest.  For homeowners and gardeners looking to identify the beetles' presence on their property, look out for the beetle's metallic green hue.

In the early stages of EAB infestation, symptoms are not readily apparent. This makes the infestation difficult to notice until dying ash trees become visible. The EAB takes between one to four years to destroy a single host tree, and each year the insect is present, it has an opportunity to repeat its lifecycle, increasing the number of pests. The EAB emerges as adult beetles in spring, leaving D-shaped exit holes in the bark of the ash tree.

While not relevant for all homeowners, the presence of woodpeckers may be a sign of Emerald Ash Borer infestation. Frequently, trees bearing a lot of woodpecker markings are infected with the EAB.

The best course of action is to remove the infected tree before the maturation and spread of the pest in spring.  Even if property owners do not detect the presence of the EAB until trees are terminal, tree removal is still required. Calling in a tree expert, such as those at Birch Tree Care, is recommended. Homeowners will need to remove the dead tree but also get help in detecting signs of infection in other trees.

When it comes to managing the spread of the EAB, homeowners, governments, and tree and plant experts all play a role.  The emerald ash borer is most commonly spread by the transportation of firewood. However, the insect can also be spread through the movement of other infested ash wood items, such as some packing material. The US Department of Agriculture strongly recommends that individuals living in infected areas not move firewood.

If you think your trees may be infected by the Emerald Ash Borer, call Birch Tree Care for a free quote.