Alongside bark beetles & Root Grafts(n.+v.)

Dutch elm disease, which is caused by a fungus, led to devastating losses of American elms when it was first revealed in the 1930s. Ophiostoma ulmi is primarily spread by the European elm bark beetles. The beetles themselves usually cause a little harm, but the beetles that emerge from infected trees carry spores of the disease fungus on their bodies. There are two main ways the disease can spread – alongside bark beetles and root grafts.

When trees have infected, they begin to develop a yellowing and wilting of the leaves. Then the leaves die, the branches die, and with a few months, the whole tree is dead. Although discolored wood can be a symptom of this disease, the only sure diagnosis is to take a culture from that wood to see if it contains the fungus. Furthermore, the only hope of preventing the disease’s spread is to immediately identify and remove diseased trees, and try to diminish the population of bark beetles through the use of pesticides.

As for root grafts, a technique called girdling can help prevent it, which is when you cut a 2-inch trench all around the trunk of the tree to prevent the fungus from spreading to the roots. In addition, fungicides can be used to kill the fungus itself in the early stage of infection. Unfortunately, it generally only works when other measures are also being taken to prevent spread of the disease.