When it comes to the future of ash trees in the Grand River watershed, the News is grim.
There are only two options for ash trees and the GRCA is doing both of these: arranging to take infested ash trees down before they become a hazard to people and property, and treating a few healthy ash trees with a bioinsecticide to keep them alive. Both options are costly.
“Unless we see a significant surprise on the part of nature, virtually all untreated ash trees over a couple of centimetres in diameter will be gone in 10 to 15 years. In some locations, such as at the head office in Cambridge, it will be even sooner – seven to 10 years,” says Ron Wu-Winter, the GRCA forester.
The ash trees are being attacked by the emerald ash borer (EAB) beetle, which has been dubbed “a beautiful killer.” The EAB was first found in Ontario in 2002 and was first noticed in the Grand River watershed at Puslinch Tract, just east of Cambridge in 2010. These were the first ash trees that fell victim to the Eurasian insect. Other ash trees within the watershed were so weakened last winter that they came down during the ice storm and wind storms.
Cousin of the lilac and olive tree, the majestic ash trees were a popular replacement for the elm trees that had been devastated by Dutch elm disease, beginning in the 1960s.
The attack on the local ash trees is already well underway in many locations within the Grand River watershed, an area the size of Prince Edward Island. The GRCA owns a lot of land and as a result has lots of ash trees with which to contend.
Forests with more than 30 per cent ash face a serious threat to their overall structure and function once the ash are infested. Fortunately, there are not many of these kinds of forests within the Grand River, and they are not large. Most forests will survive the loss of these trees.
The magic of ‘neem’
Another bit of good News is that healthy ash trees that are examined by a forester and found to be free of EAB can be treated with an bioinsecticide. The neem tree from India (the name is derived from the Sanskrit “Nimba” meaning “bestower of good health”) has turned out to be a crucial weapon in Canada’s battle against the ash borer.
In India, neem is regarded as a miracle plant. Everything from toothbrushes to painkillers is made from parts of this tree. The neem tree’s seeds are the source of azadirachtin, a natural insecticide, which is used in TreeAzin, the product developed in Canada to combat EAB.
“TreeAzin kills EAB larvae and also reduces EAB fertility and egg viability when EAB females feed on the tree’s foliage, providing up to two years of protection,” according to Trees Canada. “TreeAzin is effective at protecting trees without causing damage to passing wildlife or pets, nearby plants or gardens, pollinators including bees, or people. It is one of the few tools we have to protect healthy ash trees from EAB where they are injected, one by one.”
TreeAzin is a systemic insecticide that can be injected directly into the base of the ash tree at several locations. Ash trees need to be treated with injections every two years for at least eight to 10 years in order to keep them alive.
Treatment is only suitable for the trees that are still healthy, are structurally sound and showing little to no signs of decline due to the insect.
200 lucky ash trees
Among his many other responsibilities, Wu-Winter is searching out 200 healthy ash trees at locations across the watershed to inject them with TreeAzin. In the ash tree lottery, these are the winners.
The GRCA’s goal for this program is to save the unique genetic material in local trees. Another goal is to keep ash trees for their aesthetic value and the unique services that they provide, such as providing shade on a beach. Keeping these trees alive will allow future generations to see what an ash tree looks like.
The trees being selected by Wu-Winter are usually within parks or near recreational areas. Not all 200 trees have been selected yet, but the plan is to have them all selected and injected this summer.
In addition, cottagers at Belwood and Conestogo lakes can have the ash trees on their property assessed. If they are found to be healthy, the cottager can cover the cost of the TreeAzin product, while the GRCA will cover the cost of the equipment and labour related to the injections.
“There is a feeling of urgency to doing this, because we need to start injecting these trees before they start to decline. If we do it too late, then the success rate won’t be as high,” Wu-Winter says.
Any trees that are not injected will need to be taken down.
While the GRCA staff have been bogged down by tree removal in the wake of the ice storm last December, they are just at the beginning phase of removing infested ash trees. The removal program will accelerate, taking more time and resources in coming years.
“Both options are expensive. We are treating 200 trees, so the bulk of the work is going to be hazard tree removal. The quantity of trees being treated is a token compared to the overall number of ash trees, but it is important for genetic preservation, and keeping the heritage of the ash tree.”
The cost of treatment to the GRCA is $15,000 each year just for the TreeAzin. This is a significant cost to keeping ash within the watershed, but the cost of removal can be high for large trees.
In some cases, especially in urban areas, it makes economic sense to treat a tree because the cost of removing a large tree close to a building is expensive. It can actually be cheaper to treat a tree for 10 years than to remove it.
If you have ash trees you want to protect or if think your trees might already be infested with emerald ash borer, contact an arborist who has been certified by the International Society of Arboriculture to have them treated with this extract.
Buy local, burn local
EAB is the most recent in a series of species-specific attacks on trees that has resulted from invasive bugs inadvertently arriving in North America from afar.
Local trees have little or no resistance to these foreign invaders and the results can be devastating. This has been the case with Dutch elm disease, beech bark disease and pine shoot beetle. All of these diseases were brought into North America from other parts of the world and then spread as wood was moved from place to place.
Now some American states have laws that prevent people from moving firewood more than 50 or 100 miles.
When you buy wood for camping, get firewood locally – and burn it on-site. A campfire helps make trips to the great outdoors memorable, but firewood can also destroy the natural treasures that make camping and other outdoor activities enjoyable.
In fact, firewood infested with an insect or disease that is moved to a further location creates a “hot spot” – much like in a forest fire. Once started, it spreads the pest and its damage to the environment much farther.
While emerald ash borer is established in many parts of the Grand River watershed, signs of it haven’t been found at other locations, so the authority urges everyone to take care and buy and burn wood locally.
