Look at the reference I gave on this thread ;
http://www.oznet.ksu.edu/path-ext/f...Elm%20Trees.asp
Make sure you begin the first fungicide treatment in the spring, at bud break, and continue every week for at least four weeks when the leaves are fully developped.
Make sure also that you put the recommended dosage (no more no less) than what is given on the label of the fungicide and that every part of the plant is ciovered by the spray.
Best of luck.