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<br />How to Identify and Manage Dutch Elm Disease <br /> <br />Page 5 ofl6 <br /> <br /> <br />Figure 3. Brown streaking develops in sapwood of <br />branches infected by Dutch elm disease fungns. Streaking <br />is visible here (from left to right) in: (I) the newly <br />formed sapwood, (2) spring sapwood overlaid by <br />Wlinfected summer wood, and (3) is absent in an <br />Wlinfected branch. <br />(Photo courtesy of the America Phytopathological <br />Society.) <br /> <br />Distinguishing Dutch Elm Disease <br />From Other Problems <br /> <br />Other pest problems commonly observed on elm include leaf spot diseases, which cause <br />dark spots of dead tissue in the leaves, and elm leaf beetles, which eat holes in the leaves. <br />These problems are easily distinguished from DED. Elm leaf beetles do not carry the Dutch <br />elm disease fungus as elm bark beetles do. <br /> <br />Two other diseases, elm yellows and bacterial leaf scorch, are more easily confused with <br />DED. The symptoms of these diseases are compared to DED in table 1. <br /> <br />Table 1. Comparison of symptoms of three elm diseases. <br /> <br />Dutch Elm Disease Elm Yellows Bacterial Leaf Scorch <br />Initially affects individual Affects the entire Damage initially observed on <br />branches crown. single branches, and spreads to <br /> entire crown; oldest leaves <br />OR affected first. <br />Affects lower crown nearest <br />root graft. <br />Leaves wilt and turn yellow, Leaves turn yellow Leaves brown along margin, with <br />then brown. and may drop early. a yellow halo. <br /> <br />http://www.na.fs.fed.uslspfo/pubslhowtos/ht_ded/ht_ded.htm <br /> <br />8/25/2004 <br />