The County of Renfrew is letting land owners know that spongy moth (formerly known as the LDD moth and Gypsy moth) will continue to impact plants and trees across the region. 2021 was a record year for the invasive pest that can eat one square meter of leaves in a season. Based on the egg mass surveys conducted, defoliation in Renfrew County has the potential to be severe again in 2022.
County of Renfrew Forester Lacey Rose tells myFM spongy moth outbreaks usually occur every seven years and last three to five years. Rose says healthy deciduous trees can survive two to three years of defoliation, but conifers are more likely to suffer branch dieback or tree death. She says in our area, the caterpillars seem to prefer poplar, birch, oak and willow trees.
She notes in most County of Renfrew forests she works in there hasn’t been as many egg masses as previous years. Rose says the Calabogie, Burnstown, Barry’s Bay, Killaloe and Round Lake areas were most impacted by the spongy moth in 2021. Rose is hopeful that areas that have seen two years of defoliation are through the worst of the outbreak.
Rose says homeowners can scrape egg masses off trees and outdoor furniture into soap water, leave them for a few days and dispose of them, or burn the egg masses. Once eggs hatch in May, landowners can consider purchasing Btk (Bacillus thuringiensis kurstaki) from local hardware stores to use on feeding caterpillars.
Rose says the spongy moth has one of the least impacts on forests health. She says Beech Bark Disease and Emerald Ash Borer kill almost every tree they infest.
Rose says both are present in a wide area, spreading rapidly, and once infested, trees are prone to mortality within five years.
Rose says signs of the Emerald Ash Borer is present is by increased woodpecker activity as they eat the larvae in the bark. Branches of ash trees will also start to die back.
The Beech Bark Disease is noticeable through bright red fruiting bodies in the shape of a lemon on the tree.
Rose says on a large scale there is no control for these invasive pests. She says if property owners who have a tree they value very much and want to save should talk to an arborist about what options are available.
(written by: Rudy Kadlec)
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146,000 ha of forests in Renfrew County defoliated by LDD moth in 2021