Oak Wilt and Dutch Elm Disease

Oak Wilt Disease

What to Look For:

  • Browning of leaves from outside margin to middle.
  • Leaf drop.
  • One or more adjacent trees showing similar symptoms.

Means of Spread:

  • Feeding activities of a “sap” beetle in an open tree wound during the late spring-early summer only.
  • Root grafts with adjacent diseased oak trees.

Control:

  • Don’t keep any diseased red oak wood in whole log form. Dried and split red oak wood will usually not spread oak wilt.
  • Seal or cover, with a heavy tarp or plastic, all red oak wood suspected of being diseased .
  • Separate root grafts between diseased and healthy trees by trenching or by chemical means.
  • Remove or process diseased red oak wood as soon as possible after root graft disruption and after July of the year of the oak’s death.

Dutch Elm Disease

What to Look For:

  • Browning or yellowing of leaves in the upper branches.
  • A dark ring in the outer sapwood when looking at a branch cross-section
  • Browning or streaking of white sapwood when the bark is peeled back.

Means of Spread:

  • Feeding activities of two kinds of elm bark beetles during the growing season.
  • Root grafts with adjacent diseased tree

Control:

  • Don’t keep any elm with intact bark. This denies the beetles a breeding area.
  • Separate root grafts between diseased and healthy trees by trenching or by chemical means.
  • Detect and remove any dead or diseased elms as soon as possible.