A mysterious invasive disease has hit a stand of southeast Michigan trees, adding to a long list of threats faced by state forests. Foresters recently discovered beech leaf disease in a southern St. Clair County woodlot, the Michigan Department of Natural Resources announced Tuesday. It is the first confirmed appearance of the disease in the state. The emergence of beech leaf disease “is very concerning for our trees,” said Joanne Foreman, the DNR’s invasive species communications coordinator. Beech leaf disease can cause leaf buds to abort and leaves to curl. “We know what it is, we know it c…