What problems does the Emerald Ash Borer cause?

What Problems does the Emerald Ash Borer cause?

What is the Emerald Ash Borer and what problems does the Emerald Ash Borer cause? This tiny beetle has had a big impact on our ash trees in Ontario and continues to pose a severe threat. 

The most significant ash tree disease in Ontario is caused by the Emerald Ash Borer. The disease is spread by the Emerald Ash borer (Agrilus planipennis) which is an iridescent metallic green beetle between 8.5 to 13.5 mm long. 

Affected Species

What Problems does the Emerald Ash Borer cause? When to check your trees

The Emerald Ash Borer affects all native species of ash trees (genus Fraxinus), including the White Ash (Fraxinus americana),  Green/Red Ash (Fraxinus pennsylvanica) and the Blue Ash (Fraxinus quadrangulata). 

The Emerald Ash Borer (EAB) poses a severe threat to ash trees in Ontario. Once the EAB arrives in an area, it could kill 99% of Ash trees within an 8 to 10 year period.

As these trees are widespread in our area and play a vital role in our ecosystem and urban landscape, preventing the spread of EAB is crucial.

What Problems does the Emerald Ash Borer cause?

How did the Emerald Ash Borer get to Canada?

The Emerald Ash Borer is an invasive beetle species native to some parts of Asia. 

It arrived in North America in the late 1990s, probably in imported wooden packaging materials. It was first spotted in Canada in 2002  and has since spread to 5 provinces.

Where is the Emerald Ash Borer found in Canada?

The Emerald Ash Borer is across the southern and middle areas of Ontario, Quebec and New-Brunswick. It is also present in the city of Thunder Bay, Ontario, the city of Winnipeg, Manitoba and the city of Halifax, Nova-Scotia.

What problems does the Emerald Ash Borer cause Map

 Emerald Ash Borer Map Canada

The Emerald Ash Borer travels via infested firewood from all tree species, ash wood products, lumber, branches, bark or wood chips. It can fly up to 10km.

Emerald Ash Borer Damage

Emerald Ash Borer infestations result in severe damage to ash trees. If left untreated, EAB infestations ultimately lead to the death of ash trees. 

The beetles reside in the tree and lay their eggs in crevices in its bark. When the larvae emerge, they feed under the tree bark. This disrupts the tree’s vascular system, cutting off its supply of water and nutrients and causing irreversible damage to the ash tree.

What Problems does the Emerald Ash Borer cause? Ash bark

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What problems does the Emerald Ash Borer cause?

The threat posed by Emerald Ash Borer to ash trees in Ontario is substantial. Since its arrival in the early 2000s, EAB has spread across Ontario, leading to the widespread decline and mortality of ash trees.

Because the Emerald Ash Borer spreads so easily it has the potential to decimate Ontario’s trees leading to:

        • Impacts on the whole ecosystems in forests, as the tree composition changes and environments become more vulnerable to non native species
        • Destruction of trees in parks and urban tree canopies and the knock on effect on quality of life and the urban environment
        • Loss of shade from mature ash trees in backyards impacting on the home

What are the signs of ash tree disease caused by the Emerald Ash Borer?

What Problems does the Emerald Ash Borer cause? Ash bark

Early Signs of Infestation

The upper branches of an infected tree may exhibit a thinning canopy as the EAB larvae tunnel through the inner bark, disrupting the tree’s nutrient and water transport systems. There may be signs of defoliage, and the canopy may appear ragged. 

Initial signs of infection often include the dieback of branches, starting from the top of the tree and progressing downwards. 

Increased woodpecker activity, particularly the presence of pecked or “blonding” bark, as these birds feed on EAB larvae.

Later Signs of infestation

As the infestation progresses, shallow S-shaped galleries created by EAB larvae become visible under the surface of the bark. This distinctive pattern is a hallmark of advanced infestations.

You can see D-shaped exit holes in the tree, which are caused by the young adult beetles emerging in June or July.

Epicormic Sprouting: In a desperate attempt to survive, infected ash trees may produce shoots (epicormic sprouts) from the trunk and lower branches. These are actually a sign of the tree’s decline.

Vertical cracks in the bark: The tree’s outer bark may split or crack vertically due to larval feeding, exposing the distinctive serpentine galleries.

What Problems does the Emerald Ash Borer cause? Ash bark

Prevention of Emerald Ash Borer

Avoid Transporting Infested Wood: Do not transport firewood, tree trimmings or wood products from infested areas, as this can contribute to the spread of EAB.

Do not move yard waste or mixed tree trimmings if there is a chance that ash may be mixed in with it.

Early Detection is key. Check your trees regularly for signs of infestation and report signs of EAB promptly. Periodically inspect the canopy of ash trees for signs of thinning or dieback, especially in the upper branches. You will need to get into the canopy to look for signs of infestation in the early stages – the beetles will not be visible on the trunk or lower branches.

Look for signs of infestation in other ash trees in the local area. Emerald Ash Beetles can fly up to 10km, so you need to look out for signs of infected trees in this kind of radius. If you spot a diseased ash tree within this distance, immediately have yours checked by a professional, as it is likely that yours also has an infestation.

How to treat ash trees for Emerald Ash Borer?

What problems does the emerald ash borer cause

While treatment options for Emerald Ash Borer are available, they are generally most effective in the early stages of infestation. Often, by the time you recognise a problem, it is too late to save the tree, and the priority is to prevent its spread to other trees. In many cases, removal and replacement of affected ash trees may be the most practical and ecologically responsible option.

When is it too late to treat Emerald Ash Borer?

What Problems does the Emerald Ash Borer cause? Ash bark

It can take several years for signs of an infestation of Emerald Ash Borer to become visible. Unfortunately, this means that by the time the infestation is spotted, it has caused too much damage and the tree cannot be saved. In these cases, it is imperative that you remove the infected tree to save neighboring trees.

Signs that is probably too late to save the ash tree include:

        • Large dead branches
        • Bark falling off
        • Thinning of the canopy by more than 50%

Signs that it may be too late to save your ash trees include:

        • Thinning canopy
        • D-shaped holes in the trunk
        • S shaped galleries under the bark
        • Epicormic Sprouting

When to check your trees for signs of Emerald Ash Borer?

What Problems does the Emerald Ash Borer cause? When to check your trees

If you have ash trees in Ontario, it is crucial to check them regularly for signs of Emerald Ash Borer. The best thing is to detect the beetle itself rather than wait until you see something wrong with the tree, as by the time there are visible signs of decline, it could be too late to save the ash tree. 

Emerald Ash borers are small but adults will be seen in the tree from early June through to the end of August. You may also see them near the tree rather than on it. 

Eggs are so small and buried in the crevices of bark that they can be difficult to detect. The eggs are a creamy colour to begin with but will darken with time. 

Cream or pale green colored larvae are 26-32 mm long and can be seen under the bark during the summer months. It enters the prepupae stage in September and takes on a J shape. It will remain like this through the winter. 

Pupae can be found under the bark between April and mid July.

Full Guide to Detection of the Emerald Ash Borer

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Get in touch with Sarginson’s if you think you have a problem with the Emerald Ash Borer