Invasive Species; Plants and Insects

INVASIVE SPECIES: Plants & Insects

Invasive Plants:

Invasive plants, in this context, are aggressive non-native plants.

They have the potential to disrupt the balance in an ecosystem, displace native species – both flora and fauna – and biodiversity can be drastically reduced. There are about 500 invasive plants in Canada, most of which are in Southern Ontario.

The cost associated with this problem is huge: $2.2 billon annually to Canadian farmers which is eventually passed along to consumers. While it is more difficult to measure the cost to the environment, the impact of the resulting loss of biodiversity in combination with the effects of climate change could be devastating particularly to food security.

 How Do Invasive Plants Affect Eight Mile Point?

The McLean Reserve presently plays host to at least 10 varieties of invasive plants. Of these, the most predominant are buckthorn, garlic mustard, goutweed and periwinkle. As mentioned before, their biggest impact will be loss of biodiversity. These plants dominate and outcompete native plants and wildflowers. Even native trees and shrubs can be adversely affected.

As participants in the Managed Forest Tax Incentive Plan we are required to take appropriate steps to control invasive non-native plant species to promote forest health and biodiversity. See below for more details on the impact of Garlic Mustard and Buckthorn.

It is not too late; there are still many unaffected areas. If there is the will to do so, we can take the steps to protect the vistas, the native plants and trees as we know them today.

McLean Reserve’s Highest Priority Invasive Plants:

1. Garlic Mustard, a non-native herb brought to North America by early colonists, is now spreading across the continent at a rate of 6,400 square kilometres per year – that’s an area 10 times the size of Toronto. Left unchecked, a patch can double every 4 years. There is evidence indicating that garlic mustard changes a forest’s composition over time, creating a more favourable environment for itself, driving other species out of the understory and even changing the tree composition.

Despite valiant, manual control efforts by Eight Mile Point volunteers and students over the past few years, this species is rapidly expanding in the McLean Reserve.

Burning was recommended and tested on a patch in 2011. It turned out to be too labour intensive and had to be halted when poison ivy was encountered. Further attempts to enlist volunteers over the last 3 years have failed to generate enough help to make a significant difference.

Without sufficient manpower there are only two options:

1)   do nothing and watch the McLean Reserve deteriorate faster with each passing year until all areas are affected and the situation is irreversible, or

2)   call in experienced professionals to bring the Garlic Mustard under control with the use of the herbicide Roundup.

The use of Roundup to control Garlic Mustard is recommended under specific circumstances by the Nature Conservancy of Canada in their 2007 report Control Methods for the Invasive Plant Garlic Mustard (Alliaria petiolata) within Ontario Natural Areas.

This report evaluated the efficacy of various methods of Garlic Mustard control. Their conclusion for forested properties with a rich diversity of native species, which describes the McLean Reserve, follows:

Roundup® application is widely regarded by conservation professionals as the most effective and efficient control, and is recommended where:  Garlic Mustard populations are dense and extensive, evergreen native species are sparse, non evergreen native species are dense, basal rosettes are not smothered by leaf litter, and a labour force is more constrained in availability.

Also from this report: Glyphosate (Roundup) is widely considered the most appropriate herbicide for use on conservation lands. It has very low acute toxicity to mammals and birds and is inactivated once in contact with soil. It rarely reaches the water table or causes other known lasting negative environmental effects. The readily available form of Glyphosate, Roundup®, is only intended for terrestrial use.

A walk-through assessment of the McLean Reserve was conducted in October 2014 by Urban Forestry Associates (UFORA); experts in the arena of invasive plant control. UFORA was selected from three possible companies that employ licensed pesticide applicators.

Quotes for the work were provided by each company and UFORA came out well ahead on price and in expertise.

UFORA estimated the area of the sum of all the scattered garlic mustard patches in the Reserve to be about 1.5 acres; approximately the size of 3 Cottagers Lots. UFORA staff, if employed, would spot treat the emerging Garlic Mustard with herbicide in late April when other native plants are still dormant and unaffected by the Round-up. Four employees would work for two days to cover the entire reserve, targeting only invasive species with herbicide. Wetland areas will be excluded.

It is imperative that garlic mustard be controlled as soon as possible.

The Nature Conservancy of Canada/EMPCA – recommended approach is now our best bet to minimize damage to the reserve and the expense to the community.

Please attend the EMPCA AGM on June 28 to hear more, ask questions and to vote on this proposal.

web garlic mustard woodsSwath of Garlic Mustard in bloom

2. Common Buckthorn was introduced to North America in the 1880s as an ornamental shrub and was widely planted for fencerows and windbreaks in agricultural fields. Since then it has spread aggressively throughout southern Ontario and in other provinces. It thrives in a variety of habitats and forms dense thickets that crowd and shade out native plants. Buckthorn can spread widely with the help of birds and animals that eat its fruit, carry the seeds long distances and deposit them in their droppings. Stands of buckthorn can invade roadsides, riverbanks, mature forests and farm fields. Buckthorn can alter nitrogen levels in the soil, creating better conditions that ensure its own success while discouraging the growth of native understory species and reducing biodiversity in a habitat. The thorns can be harmful to humans or animals that come into contact with it. Manual removal efforts in the McLean Reserve have been moderately successful but more volunteer help is required in mid to late October to help bring this species under control.

web buckthorn picBuckthorn thicket (on right) in McLean Reserve. Green fall foliage helps to identify.

Other Invasive Plants, Trees and Shrubs Presently in the Mclean Reserve:
Japanese Barberry (associated with the Black Legged Tick; carrier of Lyme Disease), Norway Maple, Winged Euonymus, Lily of the Valley, Periwinkle, Ajuga, English Ivy, Goutweed (variegated and non-varieg.), Miscanthus grass, Chinese Lantern, Daylily, Honeysuckle Shrub, Weeping Willow and White Mulberry. All of these have been either intentionally planted, spread by birds or introduced via discarded yard waste. Please try to avoid these plants when planning your garden.

 What You Can Do To Prevent the Introduction of More Invasive Plants:

1. Plant native species; they are important & essential food for native insects upon which most birds rely to feed their young.

2. Not all non-native plants are invasive. Try to avoid invasive non-native plants like easy groundcovers (periwinkle & goutweed) and others already invading the McLean Reserve as listed above.

3. Google the “Grow Me Instead Guide” for alternatives to invasive but popular garden plants.

4. Never place yard waste in the McLean Reserve; this can introduce non-native invasive plants and seeds.

5. Stay on Nature Trails and mown pathways. Venturing off the trails can accidentally spread invasive plant seed into previously unaffected areas and Poison Ivy may be encountered.

6. Monitor your own property for Garlic Mustard. If you require help identifying it, contact the EMPCA Roads and Conservation Committee.

7. Volunteer to help at an EMPCA Invasive Species Control event. It’s a great way to learn not just about invasive plants but also our beautiful native wildflowers.


Invasive Insects:

Similar to invasive plants, invasive insects are non-native insects that have evolved in, and been introduced from a different continent. Since, in their new environment, they have no natural predators or pests that keep them in check, these insects have the potential to cause immeasurable damage..

1)   Emerald Ash Borer:

Since it was first discovered in the Windsor-Detroit area in 2002, the Emerald Ash Borer, aka EAB, has killed 10s of millions of trees in S. Ontario, parts of Quebec and the N.E. section of the U.S. Native to China, EAB is considered the most destructive forest insect to ever enter the US and poses a major economic and environmental threat to urban and forested areas in Canada and the U.S.

All species of the native North American ash trees are highly susceptible to EAB.

web EAB pic

Typically, within six years of an infestation arriving in a woodlot, more than 99% of the ash trees have been killed. This extensive mortality increases the likelihood of invasion of forests by invasive plants.

In 2014 this invasive beetle was discovered in Bradford Ontario and is spreading quickly northward. Barrie – though not yet affected – is already taking steps to cut down thousands of ash trees to reduce the long-term cost and impact of EAB on the city’s tree canopy. Some specimens are being treated with injections of a systemic bio-insecticide called TreeAzin. The treatment can be very effective but injections are required every two years and the tree’s survival is not guaranteed.

Eight Mile Point & Emerald Ash Borer:

It is estimated that EAB will be here within 5 years and that we will lose most if not all of our mature ash trees.

Homeowners & EAB:

For those who think they may have ash trees on their property:

1)   contact an arborist ASAP for advice

2)   consider the importance of that tree to you (for shade, aesthetics or sentiment) and the cost of the biennial treatment vs the cost of removal.

3)   be aware that an affected ash tree quickly becomes structurally weak and is particularly hazardous for arborists and anyone in its vicinity.

McLean Reserve & Emerald Ash Borer

Considering that the amount of ash in the McLean Reserve forest is estimated to be 40%, the cost of treatment would be prohibitive. In the future, as these trees succumb to the borer, those that present a hazard (near trails) will be removed. The rest will be left to return to and feed the soil.

Openings in the tree canopy – created by the dead and dying ash – will allow more light onto the forest floor. This will promote new growth which can be good or very bad particularly if the existing invasive plant species are not brought under control.

Immediate steps to reduce the amount of Garlic Mustard and Buckthorn, before the ash begin to die, are strongly recommended.

2)   Beech Bark Disease

Beech bark disease (BBD) is a non-native insect-fungus complex caused by the beech scale and the canker fungus. The beech scale was introduced into North America in the 1890s on European Beech seedlings shipped from Europe to Halifax. The canker fungus probably arrived in North America in a similar way. The beech scale and the ensuing disease have gradually spread through eastern North America. In 1999, BBD was officially confirmed in Ontario, and has since spread throughout most of the local range of our native American Beech.In Ontario’s hardwood forests, some scattered large beech trees are not attacked by the beech scale.

These trees are disease resistant, as the canker fungus only infects scale-infested trees. However, resistance is rare and found in approximately 1% of beech in North America.

The more typical course of the disease is:

  Rapid mortality of large, old trees girdled by cankers.

  Slow decline and death of beech with less serious infections and of regeneration in aftermath forests.

  Increased susceptibility to decay fungi and insects, leading to stem breakage.

  More beech sprouts and seedlings produced around dead trees, which also become infected.

  Decreased seed production from diseased trees that have lost >25% of their crown.

There is little to be done to prevent BBD. Beech trees on private property should be monitored and removed if/when they become hazardous.

web beech bark disease 1Signs of Beech Bark Disease

web beech on boat 1

Unmonitored diseased Beech – Eight Mile Point 2009