Emerald Ash Borer — Where Are We Now?|
|"The invasion of the Emerald Ash Borer is an environmental disaster with an impact of the magnitude of Hurricane Sandy — and potentially of the sum-total of all hurricanes of the past 5 years."
|| Statement made at a 2013 EAB Community Information Presentation.|
EAB Beetle Facts
In 2002, the invasive Emerald Ash Borer beetle was identified in the Windsor/Southeast Michigan region. It probably had been present for a few years prior to that. Originating in Asia, the destructive pest was most likely transported to North America via infested shipping materials. To date, it has claimed in excess of 100 million ash trees. Although the beetle has a maximum natural spread rate of about 15 kilometres per year, it has now migrated to more than 20 US states (mainly in the northeast) and 2 Canadian provinces — in just 12 years. Distribution to new territories has been mainly via the movement of firewood by unsuspecting individuals.
Authorities have now declared all infested regions quarantined as to Ash wood transport — with fines of up to $250,000 for violators. In 2012, one individual was fined $10,000 for ignoring a 10 m square road sign for the sake of a half cord of firewood in his pickup truck. This is serious business.
The Emerald Ash Borer has a normal life cycle of 1 year. The adult beetle emerges in late May and flies into the crown of the ash tree where it feeds on the leaves for a short number of weeks. The leaf damage of this phase is minimal. During this time the female will lay from 70 to 250 eggs in the rough furls of the bark. The adult beetle soon dies. The eggs hatch in about 2 weeks and the tiny larvae then burrow into the bark and begin feeding. Over the next few months, they feed voraciously in the tender cambium layer, leaving serpentine trails between the bark and sapwood. With several hundred (or thousand) of these larvae feeding, this process in effect girdles the tree and prevents the nutrient flow between roots and leaves. The tree soon dies. The larvae winters under the bark, and in the spring goes through 4 pupae stages as it changes form into the beetle. In late May, the adult beetle exits the tree leaving behind the classic "D" shaped hole. The cycle repeats. As a note here, it appears that trees less than 2.5 cm in diameter seem not to be affected — probably because their bark is smooth and unsuitable for egg deposit. However, as they grow, they too will become infected and then be lost. It is unlikely that any ash will survive for the future.
Based on the experiences of other communities, it appears to be about 5 years from the first detection of the beetle to the die-off of the majority of ash trees in the area. We have been watching the progression of the infestation as it marches toward us. Although we have observed distress in some of our trees and the deaths of a few, the peak of the infestation has yet to be realized. Yes, the borer is in the woodlot, and it is expected to be much more noticeable by the end of this summer. Next summer, we expect to see the collapse of our ash population where large numbers fail in a short period.
Previous Similar Issues
In the early 1960's, the Dutch Elm Disease killed the majority of the majestic Elm trees in Southern Ontario. Since such die-off was a new experience, there was no response plan for this problem. Most areas just stood and watched as the stately trees died — and then began dropping large branches on the unsuspecting below. Authorities reacted by then attempting to cut down the couple-of-years-dead trees, only to find that many of the woodcutters suffered serious or fatal injuries in the process. As a result, the dead elms became known as "Widow Makers", for obvious reasons. Major lessons were learned for future responses to large scale tree die-off situations.
In the early 2000's the Sawyer Woodlot faced the sudden die-off of most of our Bitternut Hickory trees due to an infestation of the Hickory Bark Beetle. A significant part of Southwestern Ontario was impacted. Having learned from the Dutch Elm situation that doing nothing was not a viable solution, we chose to remove a few trees as logs and the remainder as firewood. The suddenness of the die-off and the rapid deterioration of the wood resulted in our response being a bit tardy as the few logs removed were of marginal quality. Volunteer woodcutters were able to bring down all major dead trees safely — but it was a very risky operation. The lesson learned was that the reaction to such a situation in the future must be quicker and more decisive.
Our Emerald Ash Borer Response
As of 2010, it has been estimated that the Sawyer Woodlot contained 10,000 ash trees. Of that number, at least half of them were of a diameter smaller than your wrist. The majority of those would be lost due to natural attrition. Of the remainder, about 1000 were larger significant specimens at or approaching maturity. The balance were of various lesser sizes — perhaps described as the "tweens, teens & youths" of the woodlot.
When developing our strategy regarding the approaching EAB crisis, the following considerations were front and centre:
- What was learned from previous die-offs i.e. Dutch Elm Disease, Hickory Bark Beetle
- Time-line for impending die-off
- Effects of various possible responses
- Safety of woodlot visitors and association members
- Impact on wildlife
- Impact on remaining trees and vegetation
- Overall woodlot health
- Resources available
- How are other jurisdictions responding
- What would Otis do?
The first strategic decision was easy — doing nothing was not an option. To do so would mean closing the woodlot to all visitors for probably 5 years, or perhaps longer.
The second strategic decision was almost as easy — the significant ash trees in the human traffic areas must be cut down before they are dead (or as soon as they die) for safety reasons. Those in remote areas could be allowed to die and fall naturally for the benefit of wildlife.
Subsequent decisions were not as easy. Do you log; simply cut and drop; remove wood of value; chip & mulch; or somewhere in the middle? Resources are limited — both human and financial. Which route is of the greatest benefit to the woodlot itself? What are we reasonably able to achieve?
In 2012, about 200 trees were removed as logs and firewood in anticipation of the Emerald Ash Borer infestation, as well as for general woodlot thinning. In 2014, a further 161 ash trees were removed for logs while they had some market value. All of those removed were expected to die within 2-3 years due to EAB, and to soon become liability issues. Even with this culling, there remain several hundred ash trees that will have to be handled in the near future. They will die and they will fall down. With the significant human traffic in the woodlot, that is a concern.
The Board of Directors is closely monitoring the situation and will take down those dead and dying trees that pose a threat to woodlot traffic. Cleanup will be ongoing but will probably fall short of leaving a pretty scene. However, wildlife does not appreciate the human definition of "pretty". Wild turkeys and other critters have already set up housekeeping in our less than pretty brush piles. To them it is paradise.
Safety is our top priority and our continuing response will support that. We will attempt to stay ahead of the situation and not make the mistakes of the Dutch Elm era. Hopefully, the woodlot can remain open to visitors. EAB has been an unwelcomed diversion from the hopes and wishes of our association. However, EAB is reality. It is a daunting challenge, but we are dealing with it. We are moving forward. We are doing the best we can. AND the sun will rise tomorrow.