Benalla’s shady elms are feeling the effect of elm leaf beetles, but the Council is trying a different method of treatment to keep the trees healthy.
Many of the rural city’s approximately 792 elm trees are affected every season by the beetle, and the pest’s life cycle means that damage is becoming evident now and will become more obvious in coming weeks.
Elm leaf beetles drill through the leaf to lay their eggs on the underside. When the larvae hatch, they eat away the softer part of the leaf, giving it the distinctive “skeletonised” appearance. The damaged leaves then die and fall from the tree. In severe cases, the tree may lose most of its leaves. While this looks alarming and unattractive, the trees will recover and regrow their leaves. Trees affected by elm leaf beetle are not at risk of dying.
The Council treats its elms every three years by injecting diluted pesticides into the soil at the base of the trees. The pesticides are pulled up through the trunk in a process called transpiration. A drier than usual Spring however means the trees have not taken up the pesticide as effectively, so the Council is trialling injecting the pesticide directly into the trunk of the worst affected trees to eliminate the pest.
“People may be concerned about the appearance of the trees but they are not at risk of dying from the infestation, given our regular treatment program,” said Veronica Schilling, General Manager Development and Environment.
“Elm leaf beetle is widespread across south eastern Australia, and this is an ongoing issue that all municipalities with elms as street trees have to deal with,” Ms Schilling said.
“As we plan for new street trees we are choosing hardier species that are less susceptible to pests and drought, but for now we need to manage the trees which are such an important part of our local environment,” she said.
“Our highest priority for treatment is the heritage-listed elms in the Benalla Botanical Gardens, some of which are the only examples of their type in the Southern Hemisphere, and these trees are in very good condition.”
Local residents who want to help keep the streetscape healthy should treat any elms on their property which are affected by the beetle, Ms Schilling said, and they should consult a qualified arborist to do so.
“If we take as many beetles out of the ecosystem as we can, then we will help to preserve these grand and beautiful trees for our children and grandchildren to enjoy,” she said.
If anyone is concerned about the health or safety of a street tree, they should contact the Council’s Parks Coordinator on (03) 5760 2600.