Dutch elm disease is a fungal disease that can be spread by the elm bark beetle or through an infected tree's root graft. Dutch elms that contract the disease via beetles feeding on their wood may take a few years to die. But those infected through a root graft will decline much more quickly. Dutch elm disease is quite serious and has killed millions of Dutch elms across North America.
Keep a constant, close eye out for signs of Dutch elm disease beginning in early spring. Initial signs of infection are wilted, curled and yellow leaves in one or more of the tree's very top branches. If you think that you have spotted Dutch elm disease, call a professional immediately for advice on the appropriate next steps.
Burn or bury any Dutch elm firewood on your property. This dead wood is prime breeding ground for the elm bark beetles that spread the disease. In some areas with a history of Dutch elm disease, possessing this firewood is actually illegal.
Keep your tree well pruned. Removing broken or non-producing branches helps Dutch elms build resistance to the disease. However, do not prune between April and late July when elm beetles are active, or they will feed on the wounds and make contraction more likely. If your area has a history of Dutch elm disease, there may be laws dictating when you can prune your Dutch elm.
Kill any elm beetles on your Dutch elm. Spray your Dutch elm with an insecticide like Methoxychlor, Sevin or Dursban in April when elm beetles first become active. But take care to read application instructions carefully before applying any of the above insecticides. They are quite toxic and can harm you or the environment.
Inject ELMguard into the trunk of your Dutch elm tree. ELMguard is a newly developed immune stimulant that builds Dutch elm's resistance to disease.