Urban trees also at risk in drought

This summer's U.S. drought could damage trees as well as agricultural crops, and some could die or be affected for years to come, researchers say. Although trees have deeper moisture-reaching roots than agricultural crops, it doesn't make them immune to prolonged drought, Purdue University urban forestry specialist Lindsey Purcell said. "Drought can have a major impact on tree health and survival by effectively slowing and reducing growth," he said in a Purdue release Thursday. "If drought is severe enough or lasts for a prolonged period of time -- such as what we're experiencing now -- it also can cause death to all or portions of a tree." A more common effect of drought is to reduce a tree's ability to withstand insects and diseases, he said. A water-deprived tree will see a significantly lowering of its energy reserves needed to produce chemicals that ward off pathogens, he said.