Arkansas landowners may be seeing more dead pine trees in the next month as drought, Ips beetles and time exact their stealthy toll.
"We will be seeing lots of trees that will seem to show up dead overnight within the next month," said Caroll Guffey, Extension forestry program associate with the University of Arkansas Division of Agriculture. "The trees are already dead but don't know it yet."
Guffey said the affected trees were probably "attacked and killed last year," but the damage is now just beginning to show.
The deaths are part of a domino effect that starts with stress.
"These stresses can come from drought or even flooded conditions, or from too many trees growing too closely together and competing for limited soil moisture and nutrients.
"Normal, healthy trees have mechanisms to ward off attacks from the insects, such as producing pine pitch, that sticky substance that comes out of wounds.
"The pitch can kill the insects as they are trying to eat through the bark of the tree to lay eggs in the inner bark of the trees. When trees are stressed, especially from drought, they don't have enough reserve moisture to produce pitch and the beetles can make a successful attack."
The cycle begins when the adult Ips bark beetles, which are native to Arkansas, eat into the inner bark and lay eggs. When the eggs hatch, the larvae eat the inner bark of the tree.
"If enough larvae eat around the tree's inner bark, they effectively girdle the tree, causing it to die. The larvae then emerge and go looking for another tree to repeat the cycle."
Since the stressed trees already have shut down because of the drought, "the tree does not know that it has been girdled until it starts growing in the spring, and runs out of the stored food and water and starts trying to bring up more from the roots," Guffey said. "This usually happens in May or June, and then the tree needles quickly turn yellow, then red, then brown. Many landowners and homeowners think that something killed their trees overnight, but actually it was done last summer and fall."
Bark beetles normally increase the year following a drought. It takes a while for beetle predators to build their own populations, but when they do and when moisture levels return to normal, beetle infestations usually only last one season.
For more information on forestry contact your county Extension office or visit www.uaex.edu.