Elms are beautiful and majestic trees that are certainly worth the disease prevention measures available against the devastation of Dutch Elm Disease (DED). Quick to wipe out Elms, DED is caused by a fungus that leaks toxins into the xylem (water-carrying vessels) of trees. Ultimately, water flow is so impeded that the trees wilt and die.
DED is spread not only by the elm bark beetle, but also from tree to tree through grafted root systems. So if you have elms next to each other and the disease has infected one, it may make sense to sever any grafted roots. Unfortunately, once the disease travels to the root system of a tree, its chances of survival are almost nil. If, however, the initial infection takes place in the crown, then treatment with a control and sanitation pruning to remove infested areas can be a viable treatment option.
Although we have disease resistant elms available to us now (Princeton, Liberty, Valley Forge, Olmstead are the most common available in the nursery trade), it will take a lifetime for these trees to reach the size and form of some mature elms. Dutch Elm Disease is very heavy this year and we have been injecting larger groves of elms through Central Park. We will also be beginning to treat elms throughout Riverside Park this week and for many residential and commercial clients.
Injection treatments are made by drilling at the base of the tree and pumping a control through the vascular system. Depending upon size and weather, one treatment can take up to 6 or 8 hours. Treatments are repeated once every 3 years, and the drilling site is small and heals relatively easily. I cannot stress enough that investment in this type of preventative treatment program is well worth avoiding the deterioration and removal of a beautiful tree.
To learn more about Dutch Elm Disease and available treatments, visit http://www.rainbowtreecare.com/diseases/dutch-elm.asp.
Take a look at some photos I took of trees suffering from DED the other day in this slideshow:
-Ken Almstead
