The Northern Red Oak is New Jersey’s state tree and it, along with other oak trees are under attack. If the attacks came only from one direction, this would likely be solvable, but this is NOT the case. Oak trees are loved for their stately statute, interesting leaves, and beauty in all seasons. Having your oak trees looked after by Precision Tree and Landscaping assures that your trees will remain healthy for many years to come.

Oak wilt

Oak wilt is an aggressive, tree-killing disease of oaks. The disease is caused by a fungus called ceratocystis fagacearum, which causes the vessels that carry fluids up through the tree to become clogged. The fungus will enter either at a fresh wound on a tree or through the roots connecting healthy and diseased trees. As a result, the tree is unable circulate water and nutrients to its branches and leaves, so it starts to die. It will kill some within months, most die within a year.

It has been known to cause serious damage to red and white oak trees, traveling from tree to tree, infecting the root system and ultimately killing them. Red oak species are affected more frequently than white oak species — and are killed off more quickly.

Signs of infestation include:

  • Fungal spore mats grow beneath the bark
  • Bark cracking – which gives off an odor that attracts sap-feeding beetles. Fungus spores then attach to the bugs and the beetles spread the fungus from tree to tree.
  • Leaf discoloration. In May, leaves will turn dull green or bronze, will look water soaked, turn yellow and fall.

There is no treatment for this the fungus, infected trees must be cut down as well as any nearby oaks. Groups of oak trees commonly graft their roots to each other, forming a continuous underground network. That makes it easier for the fungus to spread through an entire group.

The fungus stays alive in the soil for five to seven years, and even in dead oak wood for a year. Do not replant oak trees in the affected area.

Gouty Oak Gall

A Gouty Oak Gall is an irregular plant growth that can grow up to two inches in diameter. Although the galls are unsightly, the galls are more ugly than unhealthy for the tree. The galls are formed by the gouty oak gal wasp that lays its eggs into the plants tissue of the tree and causes the tree to form galls around the eggs.

Heavily affected trees may be more susceptible to storm damage. Due to the larvae being inside the tree, pesticides are ineffective.

The oaks most affected are:

  • Scarlet oak
  • Red oak
  • Pin oak
  • Black oak

Scarlet oak sawfly

The scarlet oak sawfly, also known as the oak slug sawfly, is capable of killing red and white oak trees by skeletonizing the tree’s leaves, feeding on the lower surface of the leaves, leaving only a fine network of veins which gives the leaf a transparent appearance.

Signs of infestation:

  • Skeletonized/ transparent leaves
  • Defoliation starting in upper crown
  • Larvae feeding on leaves

Repeated defoliations may kill the tree. Red and white oaks are often targeted.

Oak Anthracnose

Trees in both the white and red oak groups are susceptible to a grouping of fungal leaf diseases called anthracnose. When the weather in the spring is cool and wet, which is often typical of a New Jersey Spring, anthracnose is more likely to spread.

Leaf symptoms:

  • Brown spots or patches that expand outward to the leaf margins.
  • Brown, dead areas along leaf veins
  • Leaves may appear to be scorched by the sun.

The solution is to Prune and destroy dead twigs and branches during dormancy; a fungicide will need to be applied to protect new leaves and branches.

Armillaria Root Rot

This root rot involves a mushroom that forms on the tree in the autumn. The mushroom can grow up to 6 inches and often accompanied by dark brown rhizomorphs (stringy threads) found under the tree bark or on the surface of the trunk or roots. This is a widespread disease among oak groups and infected trees must be removed as well as their roots.

Powdery Mildew

This disease is caused by several fungi, and the symptoms consist of a white, powdery growth on leaf surfaces. Foliage may be malformed. No control measures are recommended since this disease develops so late in the year that no significant damage occurs.

Hypoxylon Canker

This is a white-rot fungal disease attacks primarily white oak, southern red oak, post oak and water oak that have been stressed. Keeping trees healthy is the best way to avoid it entirely.

It can show up as:

  • A silvery fungus
  • Sunken patches of bark
  • Dead branches

As you can see, there are any number of fungal, insect and environmental factors that can negatively affect oak trees. The professionals at Precision Tree and Landscaping can steer you on a path for healthy trees!