This bulletin presents guidelines for extending the life of the remaining elms. It should be noted that DED losses are now occurring and will continue to occur. Thus, when we speak of DED control, we are referring to the reduction of the rate of loss, not to a complete elimination of the disease. Cause and Transmission of DED Dutch elm disease is caused by the fungus, Ceratocystis ulmi. This condition causes the tree to wilt and die.
Many trees die in the same season that infection occurs -some die within a few weeks.
Only a few live longer than the second or third season and even fewer recover completely. All elms are susceptible to DED, with the American elm being the most susceptible. Chinese and Siberian elms are highly resistant to the disease, although individual trees have died from the disease in Michigan. Several hybrid elms, produced both in this country and in Europe, have been advertised as immune or resistant to Dutch elm disease. None of these hybrids are actually immune, but some of them do show resistance approaching immunity.