The tree-killing emerald ash borer (EAB) is emerging about a month ahead of schedule in Indiana because of the early warm weather, leading a Purdue Extension entomologist to urge homeowners to take steps now to protect their trees.
Homeowners who want to protect their ash trees with insecticides need to start applying them as soon as possible, Cliff Sadof said. That is because adult borers typically take flight about the same time that black locust trees bloom – a process which has started as a result of favorable temperatures for both.
"Black locust bloom has begun to occur in many parts of the state," Sadof said. "Eggs laid by adult borers will produce grubs that start drilling into ash trees in about a month."
Indianaresidents seeking advice should look to the Purdue website. Resources are available on how to identify ash trees, determine whether trees are infested, and how to take care of the problem themselves or hire a professional applicator.
Infested ash trees have several visible symptoms:
· Branches showing thin foliage at the very top of the trees.
· The presence of woodpecker holes, the result of woodpeckers feeding on EAB larvae under the bark.
· Splits in the bark that reveal curvy trails the insects leave.
· D-shaped holes the borers make when they leave the tree. Because the tree-chewing beetle first attacks treetops, the holes often are too high up to see until the tree is nearly dead.
The number of ash trees with symptoms in a neighborhood usually doubles every year. This means that from the time enough trees are damaged to draw attention to the problem, it takes three to four years for all the remaining ash trees to be killed.
"The cost of keeping communities safe from the limbs that fall from dying trees can be devastating since over 80 percent of trees die in the last three years of the local invasion," Sadof stated.
Sadof has posted a cost calculator on the website to help communities plan their response to EAB. Planning is critical to lowering annual expenses associated with EAB management.
"Most people are surprised to learn that using insecticides to save trees during the initial invasion is much less expensive than removing and replacing trees," Sadof said. "This is because after all the untreated trees have died, most of the remaining beetles starve to death or are killed when feeding on trees treated with insecticide."
Annemarie Nagle, exotic forest pest outreach coordinator for Purdue's Department of Entomology, is heading a Purdue Extension program called Neighbors against Bad Bugs (NABB) to help neighborhoods work together to lower tree management costs.
"We have been working in communities throughout Indiana to show people how EAB will affect their neighborhood," said Nagle. "Bringing this issue to the forefront before trees start dying will encourage people to act now so they can save money and save trees."
Although insecticides are the only tool available for homeowners, Sadof has been working with the Indiana Department of Natural Resources and the U.S. Department of Agriculture's Animal and Plant Health Inspection Service for the release of stingless wasps throughout the state to help kill the beetle in rural areas.
The emerald ash borer has killed millions of ash trees in the U.S. since its arrival in Detroit in 2002. In Indiana, the most extensive damage has been in the northeast, including Ft. Wayne. Most of the state north of Interstate 70 or east of Indianapolis generally is infested.
When the EAB arrived, Indiana had nearly 150 million ash trees, at least five million in cities. In most cities, at least one out of every five trees on the streets is an ash tree.