Elms threatened by beetle

Before: Elm Leaf Beetle has begun attacking this Golden Elm tree. Photo: Supplied

Before: Elm Leaf Beetle has begun attacking this Golden Elm tree. Photo: Supplied

Elm trees across the Southern Highlands could be destroyed by a beetle.

After: The same Golden Elm tree has returned to its former glory after treatment.

After: The same Golden Elm tree has returned to its former glory after treatment.

Consulting and practising arborist Guy O’Donnell B.Sc. of Elm Consultants.Com.Au has confirmed the presence of Elm Leaf Beetle (ELB) across the region. Mr O’Donnell is credited with identifying the Elm Leaf Beetle outbreak in Adelaide in December 2011.

He said eventually all susceptible elms would be attacked unless treated. “For instance, the English Elms in Middle Road, Exeter, and at the railway station are being attacked by beetles and the first larval stage. In Sutton Forest there are Golden Elms with their leaves completely skeletonised, and in Argyle Street, Moss Vale,  English Elms are also skeletonised.”

An English Elm near the railway bridge in Argyle Street, Moss Vale, has been skeletonised by the Elm Leaf Beetle.

An English Elm near the railway bridge in Argyle Street, Moss Vale, has been skeletonised by the Elm Leaf Beetle.

Mr O’Donnell said he suspected the 2017/2018 summer was the second season the ELB had been here. He said that, if not for the October frost, most elms would have presented up to 50 per cent skeletonising of their entire canopy by Christmas.

He said the beetle could not be eradicated. “We are stuck with it and its spread will only continue,” he said. However, he treats the elms using sterile stem injection which can protect them for up to three seasons. He doesn’t spray trees and doesn’t use soil injection as it is an inadvertent killer of all soil fauna and poisons the soil with systemic insecticide for more than three years.

Mr O’Donnell said initially tree owners didn’t notice the small holes occurring on some of the leaves. “When there are sufficient beetle numbers to do rapid damage, the canopy starts to show brown patches, with leaf curling and skeletonising. That’s when most people realise their tree is being defoliated,” he said. “Say you have 100 hundred beetles in October; these will produce up to 25 eggs each, so there will be 2500 young beetles at the end of December. “Generally the beetles fly up onto the lowest leaves in October to lay eggs on the underside of the leavesand chew small shot-holes through the leaves. The eggs hatch into larvae which skeletonise the leaf underside during November and December and then crawl down the trunk or drop to the ground to pupate into adult beetles, and so the second generation begins, finishing by early April.”

Mr O’Donnell began his consulting and practicing arborist business in the Highlands in 1981 and specialises in Elm leaf Beetle treatment. Details: 0412 288 626 or  https://nsw.homegiraffe.com.au/southern-highlands/elm-leaf-beetle-treatment/