Hemlock Woolly Adelgid in Nova Scotia - Update


Dennis Boot Lake (c) Parks Canada

It's been five years since hemlock woolly adelgid (HWA) was first identified in south west Nova Scotia.  

This post is an update about the bug, efforts being made to control it and specific actions for you.

Where is HWA in Nova Scotia?

Current known locations of HWA (c) CFIA

The map above shows red dots where HWA has been confirmed in Nova Scotia.  The same map from two years ago confirms HWA making a rapid march from west to east across the province.  In just two years, Lunenburg and Kings County have infestations and the Canadian Food Inspection Agency has added these counties to their restrictions on the movement of hemlock.

For a tiny insect that lives most of its life in a stationary state, incapable of moving from its feeding station at the base of a hemlock needle, the species sure does get around!

The map only shows where the bug has been confirmed.  An area could be infested and not be on the map.  There have been numerous examples of HWA going undetected for several years.  Early detection is key because it provides cheaper and more effective options for treatment.   If you believe you have seen HWA, please send an email -- with picture(s) if possible -- to hwa@nshemlock.ca

And these maps aren't telling us about the state of the trees in the western most part of the province where the first infestation took place -- many trees are dead and/or dying.  In many cases they are untreatable.  Once infested, our hemlocks deteriorate very quickly, typically living only 3-5 years.

Pesticide treatment is currently the only option for saving infested trees

If a hemlock becomes infested with HWA, the only way to prevent the tree from dying at this time is by applying a pesticide.  Ouch, that hurts to say and I wish there was another solution.  But that is the situation until biological controls are in place.

Three of the largest pesticide treatments so far include :

1- Kejimkujik National Park and National Historic Site ... "Since fall 2021, Parks Canada has treated 2,150+ hemlock trees at Kejimkujik NP and NHS. Treatment areas include high priority old-growth stands (1,200+ at remote Dennis Boot Lake) as well as important visitor areas (Jeremy's Bay Campground and Hemlocks and Hardwoods trail) with more planned this fall (Mill Falls day-use area and an area near Loon Lake falls) and even more in 2023"

Applying pesticides at Keji (c) Parks Canada

2- Sporting Lake Nature Reserve : we had an update on this project two weeks ago at its one year anniversary, see : https://www.giantsofnovascotia.com/2022/10/sporting-lake-hwa-one-year-later.html  Just over 2,100 hemlocks were treated using volunteers.

3- Scott Robinson is currently the only arborist in Nova Scotia treating hemlocks and writes ... "What we're seeing is that most trees in Yarmouth and Weymouth Counties no longer have new growth. We often recommend that clients not treat them when they are that far gone as it doesn't make economic sense. About 5 percent of the trees on Ponhook Lake are past the treatment threshold as well.  We have worked almost exclusively for cottage owners treating between 1 and 300 trees."

(c) Scott Robinson

Gary Marshall shown in the picture above first treated around 60 trees in 2021. Scott writes  ... "They are doing extremely well with new growth and dense canopies. The large tree I treated for him in the picture had some new growth this spring. It's really rewarding to see such a positive outcome and we're looking forward to doing treatment assessments in the spring."

And here is what the province has planned ... 

"Over the next five-years, the province will be conducting chemical treatments to protect high-priority hemlock stands.  These stands have been ranked and assigned a protection priority based on a number of attributes or criteria.  These include:  
  • hemlock dominant stands with existing or potential old-growth
  • stands with indigenous cultural value
  • protected areas and provincial parks
  • stands with special habitat (species at risk, watercourses etc.)
  • stands with accessibility and human use
  • stands healthy enough to benefit from treatment
  • distance to known infested areas etc.  
This will ensure that only the highest priority stands with the  greatest ecological and cultural value are protected.  Similar to what is currently being done in Kejimkujik  National Park, chemical treatments of individual trees will be conducted to protect these areas.

Beyond the short-term protection of high priority stands using chemical treatments, outreach will also be conducted to provide  information on how landowners can detect HWA and protect trees on their own lands."

The Hemlock Trail at Keji (c) Curtis Watson

Chemical treatments are a short-term solution -- what about the long term?

British Columbia's hemlock trees and hemlock woolly adelgid (HWA) coexist -- how is that possible???  The west coast forest also includes predator bugs that keep the HWA in check.  

Unfortunately, these bugs do not exist in our Nova Scotian forest.

So a simple solution would be to take the bugs from BC and introduce them to the Nova Scotian forest.  

Not so fast ... before they can be released here, rigorous testing must occur to make sure they will not attack native species and they will be able to tolerate our cold winter temperatures.

Called "biocontrol", it is a long term solution developed over the next 5-10 years for protecting what will remain of Nova Scotia's hemlocks.  

Nova Scotia is at the very early stages of this process, stating ... "funds will be used to explore biological control to provide long-term regulation of HWA populations and reduce damage to hemlock"

The challenge is to keep as many hemlock alive as possible until biocontrols are up and running.

Blessing a newly treated hemlock at Dennis Boot Lake.  Will it be safe until biocontrols are in place? (c) Parks Canada

Actions you can take to protect our hemlocks

You can help stop the hemlock woolly adelgid (HWA) from killing our Nova Scotian hemlock trees in three ways:

1- PREVENTION : do not accidentally move HWA from an infested area to an uninfested area.  

Fortunately, right now HWA is anchored to the hemlock branches and cannot move so the risk of spread is very small.  

This all changes next March/April when the first generation of eggs hatch, with more hatching in the second generation through June-July.  The young HWA 'crawlers' start looking for a new home. Many thousands fall to the forest floor and on humans and wildlife as we travel about. 

Look for a PSA in the spring with some suggested actions.

2- DETECTION : early detection of HWA means you will have more treatment options.  

Now and into the winter is a good time for you to inspect hemlocks to see if there are any signs of the bug as it grows larger and more visible during winter.  

Look for a cotton-like sac on the underside of the branch tips where the needle meets the stem.

(c) Medway Community Forest Coop

And if there is a wind or ice storm and hemlock branches are knocked down -- it is a perfect opportunity to inspect infestation levels in the upper canopy among the fallen branch tips.  

If you find any signs of HWA, please get pic(s) of the underside of the branchlets and email it to hwa@nshemlock.ca

3- TREATMENT : if you find HWA, you will have to make some decisions.  

Two pamphlets will help you. "A Landowner's Introduction to Hemlock Woolly Adelgid" is a good overview and HWA Treatment Decision Key will help you decide which trees are candidates for treatment.  

As of the fall of 2022, you will have to contact a certified pesticide operator if you decide to treat your trees.  We hope to have an update on treatment options early in the New Year.

* * *

Hemlocks in Nova Scotia are in a fight for their life.  We can all do our part to make sure as many as possible survive so our grandchildren can experience the magic of an intact hemlock forest.  

Hemlock on Sporting Lake one year after treatment (c) Martin Gray

In addition to the people mentioned above, many thanks to the following for their help with this post : Alicia Brett, Donna Crossland, Colin Gray, Jennika Hunsinger. Dan Lavigne, Ron Neville, Cal North, Matt Smith, Sally Steele and the rest of the gang at the HWA Working Group.

Sporting Lake - HWA - One Year Later

Sporting Lake (c) Paul Newton

In October 2021, an eclectic group travelled by canoe to Sporting Lake Nature Reserve in the Tobeatic Wilderness to try and save one of the few forests in Nova Scotia untouched by mankind.  It is dominated by hemlocks, some as old as 500 years.

Unfortunately, a bug called the hemlock wooly adelgid (HWA) had been found on previous trips.  Once infested, their end is imminent.

Inoculating Hemlocks at Sporting Lake (c) Tristan Glen

Private citizens, various government departments and non-government agencies came together to raise money, gather the various approvals and permits, secure the supplies and organize the effort to inoculate the hemlocks -- the only way at present to stop the bug and give the hemlocks a reprieve.  Over 2,000 trees were treated

Donna Crossland was one of the key organizers for October 2021 mission.  She returned on the Thanksgiving 2022 weekend and provided me with an update ...

THE BAD NEWS -- untreated, smaller trees that could not be treated were dead or dying

THE GOOD NEWS --  deeper into the shaded interior of the forest, most of the greenery remained intact and vivid where infestations were less advanced.  Dead HWA were observed under the hemlock tips.  The treatments had worked!

We were wise not to have waited.  It was clear now that it had been the right time to take action.

Treated hemlock at Sporting Lake, Fall 2022 (c) Martin Gray

So what are the key takeaways?

1- Check Often

  • Keep checking for HWA populations, particularly in late winter and early spring.  HWA populations can go from just a few individuals to a population explosion in just one season
  • Check crown density and do not allow the canopy to start thinning before taking action
  • Pay attention to the flush of new spring growth tips -- if the tree stops producing new tips, it may be too late to save the tree

2- Act early 

  • Particularly since Nova Scotia only has a slower-acting chemical available for use
  • If you have old growth and HWA is known to be close by, it is best to treat right away

Chemical treatments are interim and will be replaced with a predator insect that exclusively feeds on HWA controlling populations in future.

* * *

A big shoutout to Donna for making the trip to Sporting Lake and providing this update.  

In addition to her monitoring, she was there being filmed for a documentary film called "In the Quiet and the Dark", a cinematic, poetic film that is exploring the plight of the Eastern Hemlock through one woman's journey, along with the work of North American experts and passionate scientists, and community members, that have banded together to try and save the trees against the threat of HWA. 

Directed by Nance Ackerman, Produced by Teresa MacInnes for CBC television and CBC GEM to be released in the Spring of 2023.

After Fiona - ideas for the fallen trees


Hurricane Fiona was very hard on our trees here in Nova Scotia.  So many images of blow downs :-(  

Here are some suggestions for what you can do with the wood :

Do you live in western Nova Scotia and have hemlocks?

Hurricane Fiona has provided us with an opportunity in the forest.  It has knocked down fresh branch samples from high in the hemlock canopies, places we cannot usually see.  It offers an opportunity to get out and conduct some early detection of HWA using these fresh samples.  

But this time of year, the young HWA are very small and seen best using a magnifying glass or hand lens.  

Search the very tips of freshly fallen branchlets, specifically at the base of needles located on the underside of the branch.

Early detection is very important so that trees are treated while in good health and ALSO because a less expensive treatment is all that is required.  Waiting until a tree has declined will cost a great deal more because fast-acting chemicals are much more expensive and will still require use of the second, longer-lasting chemicals too.  The price essentially triples, with much less guarantee of success.

Early treatment is highly successful.  It works! But must be accompanied by early detection or a preemptive treatment before the bug arrives!

Are you a gardener?

  • use the logs for raised beds, either horizontally or vertical
  • hollow logs make awesome planters
  • chipped wood is excellent for your pathways and/or mulch and/or compost
  • hardwood can be inoculated with mushroom spores ... voila, fresh mushrooms!
  • pile the limbs in a back corner for wonderful bird habitat and eventually compost
  • hugal beds where you add wood material to raised beds
  • familiar with biochar?  it's a excellent for soil rejuvenation

Are there logs?

  • hire a portable sawmill and turn it into usable lumber

Hardwood like Apple?

  • chip it and use it for smoke wood for your BBQ

Was the tree sentimental?

  • is there is enough wood remaining in place to create a sculpture?
  • create something from the wood that will remind you of it ie: bowl, breadboard, piece of art

Are you curious about the age of the tree?

  • it's the perfect time to count the rings to know the age of your giant

And there is always the tried and true -- cut it up for firewood to keep you (or your neighbour) warm on a cold winter night!

Many thanks to Donna Crossland, Jeff Ogden and Ben Phillips for their input for this article.

Emerald Ash Borer in Nova Scotia - Fall 2022 update


Emerald Ash Borer and Nova Scotia

As fall approaches and the leaves start to change, it's the PERFECT time to identify ash trees in your neighborhood.  They are one of the first trees to change and their fall colours are very easy to identify.

So why know if there's ash in your neighbourhood? 

A nasty little bug called the Emerald Ash Borer (EAB) was found in Nova Scotia in 2018. All sightings of the bug to date have been around Bedford Nova Scotia but there is always the risk that a new infestation could occur from the movement of infested wood.  

Across Eastern North America, EAB has killed hundreds of millions of Ash trees since first being discovered in the early 2000s and some government estimates predict over 8 billion ash trees will die due to EAB.

About EAB

The adult emerald ash borer (EAB) is native to Asia and was likely introduced to North America through wood products in the early 2000s.  

EAB is a metallic green beetle between 7 - 14 mm long. (David Cappaert, Bugwood.org)

The larvae feed under the bark (Pennsylvania Department of Conservation and Natural Resources - Forestry , Bugwood.org)

The feeding creates long S-shaped galleries. (Art Wagner, USDA - APHIS, Bugwood.org) This feeding eventually continues around the tree girdling it causing branch die and eventual mortality. 

Adults emerge from the tree from D-shaped exit holes. (Jared Spokowsky, Indiana Department of Natural Resources, Bugwood.org)

Ash Trees in Nova Scotia

There are 4 native varieties of ASH in Canada, the most common one in Nova Scotia is the WHITE ASH.

A lovely Nova Scotia ash tree, note the fall leaf colour on the rightside (photo used with permission from @soap_suds

Ash leaf detail -- the leaf is composed of leaflets in opposite pairs and one at the tip. Usually 7 leaflets per leaf. No teeth on the leaflet edges or possibly a few rounded ones.  Colours : yellow, orange, red and purple.

Ash trees start to change colour around the middle of September and usually the trees are stripped by Thanksgiving.

Signs and Symptoms of Emerald Ash Borer

General yellowing and thinning of the tree foliage as well as branch and crown dieback. (Dewolf Park, Bedford, NS.   Ron Neville, CFIA)

Epicormic shoots (new growth) at the tree base. (Joseph OBrien, USDA Forest Service, Bugwood.org)

Lot's of woodpeckers (they could be feeding on the EAB larvae).

The adult D-shaped exit holes. (Kenneth R. Law, USDA APHIS PPQ, Bugwood.org)

But Not Every Ash tree under stress is affected by Emerald Ash Borer!

Please note that Ash trees across Nova Scotia have also been affected by Ash Rust.  This has been widespread the past couple of years, some areas are detecting some stem dieback as well as isolated mortality. The rust is amplified by the damp and warm temperatures we have been experiencing. Most cases it doesn't result in mortality unless repeat infestations over a number of years.  

If you suspect it might be ash rust, contact : Foresthealth@novascotia.ca  Photo used with permission from the Nova Scotia Department of Natural Resources and Renewables

What is being done to prevent the Spread of EAB?

The province (Department of Natural Resource and Renewables) and the Canadian Food Inspection Agency collaborate to monitor of EAB throughout the province :

- traps around HRM to help determine the spread radius of EAB from the original Bedford site.

- baited flight intercept traps are setup in many areas outside of HRM as part of a province-wide network of traps.

- to help determine spread, branch sampling will occur this fall/winter looking for overwintering larvae within HRM but away from the known Bedford locale.

So far this years trapping within HRM has detected beetles in a number of sites within a 6-10km radius from the DeWolfe Park site in Bedford.  To date they have not collected any EAB samples from any traps outside of the HRM area.

What can you do to prevent the spread of EAB?

You can help by not moving firewood -- it could be hiding in the bark and you could accidentally move an infested piece of wood that could infest a new area.  Please acquire your firewood where you burn it.  

Very important if you live in HRM where we know there are populations of EAB!!!

And if you think you may have found a tree(s) affected by the EAB in Nova Scotia, please report your sighting to the Canadian Food Inspection Agency by phoning 902-536-1010

Photo : @chuckwrathall

A big shoutout to Jeff Ogden from the Nova Scotia Department of Natural Resources and Renewables and Ron Neville from the Canadian Food Inspections Agency for their help.

More Information

The Borer and the Basket explores the spiritual, ceremonial, and economic importance of the ash trees for Indigenous people