Expert: Give trees a good soaking to save them from stress
CHAMPAIGN — Forget about your lawn, says Jay Hayek, just water your trees.
"That's the line a lot of horticulturalists and foresters advise these days," said Hayek, the extension forestry specialist at the University of Illinois. "The key is to have a slow, deep soaking. You do that not with a sprinkler but with a garden hose on slow to medium pressure, or you do it with a soaker hose."
Champaign-Urbana has had less than 2.5 inches of rain since June 1, and only 8 inches of precipitation since April 1. The scarcity of water and the above-average temperatures are bound to place stress on trees, he said.
"We're seeing symptoms of drought in urban situations and we're even starting to see symptoms out on the natural forest as well, typically wilting foliage and curling of leaf margins, yellowing and browning of leaves.
"It's much more prevalent in the urban areas because of the heat island effect. But I am getting some reports from the professional foresters about premature fruit drop, especially with the oak trees and the black walnut trees and the hickories. Basically the trees are aborting some of their crops."
Even trees that appear green and vigorous are feeling the heat, he said.
"The trees that are healthy and established are showing minimal signs, even here on campus," Hayek said. "But it doesn't mean that they're not under stress; they're just hiding that stress much better. The problem is that sometimes you won't see symptoms of drought for two to five years down the road. That one year of drought can compound itself."
Hayek advises homeowners to give each tree a good soaking once a week, in the morning.
"A rule of thumb is that you want 10 gallons of water per diameter inch of your tree. So a 4-inch tree, you want to give that tree about 40 gallons of water per week," he said. "And you want to do it at one time. Don't give it 5 gallons every night for eight nights. That's the opposite of what you want to do. Give it a slow, deep soaking all at one time.
And don't even think about fertilizing during these periods of drought."
Large, well-established trees are at risk as much as small, newly planted species.
"You can see oak trees, which are traditionally deep, tap-rooted species, even they can succumb to prolonged periods of drought, especially in urban conditions," he said. "Urban conditions are tough on trees. That's why we have to do supplemental watering."