Trees across Ohio and the Midwest are struggling in the arid conditions. Some could succumb or suffer for years to come, says Lindsey Purcell, a Purdue Extension urban forestry specialist.
"Drought can have a major impact on tree health and survival by effectively slowing and reducing growth," he says. "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."
More common, however, is the effect drought has on a tree's ability to withstand insects and diseases. A water-deprived tree is unable to produce its usual levels of carbohydrates, significantly lowering its energy reserves. Those reserves are needed for a tree to produce chemicals that ward off pathogens.
The drought also is providing an ideal environment for emerald ash borers, Purcell says. EAB is an invasive insect that kills ash trees.
Purcell said the drought already has left trees in urban areas with permanent damage, although it might not be evident this year. Warm weather earlier this year interrupted normal bud formation, which controls shoot length and expansion. The dry conditions that followed led to decreased numbers of new leaves within buds and new stem segments.