Seasonal Detection of Visible Dutch Elm Disease Symptoms

Abstract

Most of the lightly diseased American elms (10% or less crown wilt) that were suitable candidates for fungicide injection and/or pruning therapy for Dutch elm disease were discovered in surveys during June and early July. More treatable elms were found in areas where diseased elms were removed promptly (up to 20 work days after discovery) than where removal was delayed until fall and winter, and in areas where the smaller European elm bark beetle is the primary vector of Dutch elm disease rather than where the native elm bark beetle is the primary vector.