Dutch Elm Disease

Dutch elm Disease(DED) is a fungus disease that is carried by a beetle. The Native elm bark beetle (Hylurgopinus rufipes) is approximately 1/8 inch long, gray colored body and covered with micro scopic hair. This beetle overwinters just into the bark at near ground level. Depending upon the snow level, subzero temperatures and the length of cold temperatures will determine the number of beetles that will survive the winter. In the spring ( mid to late April) will fly and feed on the twigs and branches of elm trees. They feed at the krotches of twigs or areas where the bark is thin or in weakened areas.

If the elm bark beetle is carring spores of the DED fungus (Ophiostoma ulmi) they can be deposited at the wound area. The spores then germinate as a seed and grows down the vascular tissues or tubes of the branch. The vascular tissues are important in carring water up the trees to the leaves and manufactured food from the leaves to other parts of the tree. If the fungus gets access to this water way it will spread downward and the tree tries to close its move down. Unsuccessfully in most elm trees a wilt of the leaves occur that follow down the branch to the main branches and eventually the whole tree. Once it gets to the base of the tree near the roots the fungus is allowed to grow around the trunk and the entire tree will start to show wilting foliage. The wilted leaves turn yellow and drop off while some hang onto the branch. Those hanging on will turn brown.

Initially the wilting is not noticeable until a significant number of leaves drop occurs to the point that it resembles fall in the middle of summer. At this stage a branch sample can be taken and bark peeled back where staining can be seen in long continuous streaks in the white wood or solid browning around the entire branch.

It is imperative that tree removal is completed as quickly as possible and the wood with the bark intact hauled to the city landfill. The elm bark beetle female will lay eggs in a brood under the bark between the bark and wood. The eggs hatch and young larvae burrow tunnels perpendicular to the mother’s tunnel forming a herring bone pattern or gallery. If this gallery is in a diseased standing tree or in firewood logs, the fungus grows into these tunnels and forms spores that are sticky and are collected on the hairs of the beetle before it emerges. The young beetles emerge from the log or tree and fly to the neighbor’s healthy elm and starts feeding in the upper branches.

This is why any elm firewood, American or Siberian with the bark intact must be hauled to the City Landfill by City Ordinance. This does not mean out to my friends farm outside the City Limits. If anyone is caught hauling elm wood within the City is subject to confiscation and a fine.

The second way DED spreads within our community is through the root systems or through a root graft that forms between elm trees. This is a survival method for trees growing in limited growing conditions such as a boulevard. The roots grow together and form a bond like a graft made on an apple tree. Trees with plenty of moisture share it with other trees on sites with less water. The problem becomes when one tree is infected with DED then it too is shared with the other healthy trees. This is visible when one by one a tree line street eventually loses trees until there is a separation between the roots.

Control of DED spread via root grafts can be implemented by trenching around the infected tree. This works well in a large yard or park situation but is difficult on a boulevard with sidewalks, curb, driveways, etc.

Quick removal in both cases is the best answer. The Jamestown City Ordinance requires trees to be removed within 30 days of its identification. The tree is identified by an orange spray dot on the side of the tree facing the house. There are 5 licensed arborists in the City of Jamestown and you care encouraged to call several for an idea of costs. If one contract can not get to you right away there are also other contractors available. Removal may be vital to saving the rest of the trees in your yard.