Five acres of trees cut in Larose Forest to prevent spread of deadly disease

In an effort to stop a deadly disease from laying waste to the red pine population in Larose Forest, the United Counties of Prescott-Russell (UCPR) recently gave the go-ahead to cut five acres of forest to save the remaining trees.

The counties decided to embark on the "salvage operation," which is the first of its kind in the Larose Forest, after it became evident that numerous red pine trees in the forest were being attacked by Armillaria root rot.

The recommendation to carry out the salvage operation came from the provincial forest pathologist and was the result of much deliberation between the counties, the forest pathologist, South Nation Conservation (SNC) and the Ontario Ministry of Natural Resources' forest health specialist.

"A forest operation such as this, where almost all the trees are removed, is not the norm for Larose Forest," said Steven Huntler, forestry specialist with the SNC. "This was an extenuating circumstance where the disease was killing trees at an alarming rate and significant value would be lost (if the operation wasn't carried out)."

According to Louis Prévost, director of planning and forestry with the UCPR, the counties acted swiftly to prevent the disease from spreading.

"We had to move fast so we could recuperate some of the value of the red pines," he explained during the counties' regular council meting, held Tuesday, January 25. "There is always a risk that the disease would spread, but there's an even greater risk that all the trees will just die for nothing."

Prévost said forests are exposed to million of diseases and insects during their life cycle and most often, there is no observable impact.

"Every so often, as in this case, something comes along that causes significant mortality that can have significant impact of the forest," he stated. "This was the case in this instance in Larose Forest."

Armillaria root rot disease is caused by several closely related species of Armillaria, a parasitic fungus that lives on trees and woody shrubs. It is the most destructive and widespread disease, involving pathogens that attack the roots and base of trees.

The disease will often kill trees, either single ones or in patches known as disease centres; these centres continue to grow in size as the disease spreads outward over time.

Prévost said revenue from the salvage operation will be used to ensure the site is adequately regenerated with tree species that are appropriate for the site and resistant to the disease.

"This shows that we are looking after the Larose Forest and doing what is necessary to keep it healthy and sustainable," he remarked. "This operation helped us avoid a potential catastrophe."

In 2008, a partial harvest occurred on a stand of coniferous trees along County Road 8. The following summer, UCPR forestry staff observed the remaining trees were showing signs of disease and some had even died since the harvest.

The MNR was brought in to determine the cause of the disease and provide some recommendations on how to deal with the problem. It was determined that Armillaria root rot was the reason for the mortality of the trees in that location.

Trees with Armillaria root rot disease do not always show signs of it, but early symptoms are a decline in tree vigour, yellowing or browning foliage, and a considerable flow of resin in conifers.

The causal fungus of Armillaria root rot can remain alive for many years in rotting wood on the ground, with some root disease centers estimated to be more than 400 years old. Although the fungus usually lives on dead organic matter, it can attack healthy trees and cause major damage.