(Lewistown, IL) -- The droughts of 2011 and 2012 is continuing to take a toll on tree health. Rhonda Ferree, Extension Education in Horticulture says that trees can take three to five years to show symptoms from a severe event such as a drought. Unfortunately trees under stress are less able to fight off insect and disease problems. Plant diagnosticians at the University of Illinois Plant Clinic describe the following diseases that take advantage of trees under stress. Canker diseases are fairly common on stressed honey locust trees. Drought-stressed Elm trees are more attractive to the elm bark beetle which could care the Dutch Elm disease fungus. Pines under drought stress lack the ability to make resins to protect against Pinewood Mematodes and Pine Wilt disease. And symptoms of Verticillium Wilt are more pronounced in drought, in part because drought inhibits the tree's ability to wall off the fungus. The U of I Plant Clinic can test for such diseases. For more information, refer to the U of I Plant Clinic website at www.web.extension.illinois.edu/plantclinic/index.cfm.