How to Differentiate Dutch Elm Disease From Elm Phloem Necrosis

United States Department of Agriculture
Forest Service
NA-FB/P-11
1981

Figure 3. Nymph of whitebanded leafhopper, vector of elm phloem necrosis. Dutch elm disease (DED) and elm phloem necrosis are the two most serious diseases of elm in the United States (Figs. 1 and 2). Most native species of elm are susceptible to both diseases. Dutch elm disease is caused by a fungus, Ceratocystis u1mi (Buisman) C. Moreau, and is transmitted by two species of elm bark beetles-the smaller European elm bark beetle, Scolytus multistriatus (Marsham) and the native elm bark beetle, Hylurgopinus rufipes (Eichoff). Elm phloem necrosis is caused by a mycoplasma-like organism and is transmitted by the whitebanded elm leafhopper Scaphoideus luteolus Van Duzee (Fig. 3). Both diseases also can be transmitted through root grafts between adjacent trees.

Lester Paul Gibson, Research Entomologist, Northeastern Forest Experiment Station, Delaware, OH 43015

Arthur R. Hastings, Entomologist, Northeastern Area, State and Private Forestry, St. Paul, MN 55108

Leon A. LaMadeleine, Plant Pathologist, Northeastern Area, State and Private Forestry, Broomall, PA 19008