Invasive Species – The McGerik Homestead

Planting in a Post-Wild World: Designing Plant Communities for Resilient Landscapes

From a post on Mastodon by Catherine, I was introduced to “Planting in a Post-Wild World: Designing Plant Communities for Resilient Landscapes”. Catherine’s comments intrigued me such that I found the book to read.

I’m only part way into the first chapter but there is a lot to unpack! As I currently understand the message in the book, we can create resilient landscapes using both native and non-native species. That is, the landscapes do not have to be composed of exclusively native species of plants. I admit to leaning toward the former line of thinking but I have also allowed myself to believe that the only correct environment is one that contains only native plants.

The authors have stated that what matters is the density of plants in an environment and how self-sustaining the plant community is. By self-sustaining, they mean a community of plants that does not need continuous weeding, fertilizing, or watering. Density is a question of “is every niche occupied?”

Creeping Charlie (Glechoma hederacea) is an introduced plant to North America. Many people consider it a nuisance weed. I’ve had a mixed relationship with it. I recognize that it is viewed as a weed by many people but I also recognize its value to bees because it is one of the first flowering plants in our yard. I’ve spent countless hours pulling creeping charlie from gardens in an endless effort to keep it under control.

After partially reading the first chapter in “Planting in a Post-Wild World:”, I now know I am approaching the situation from the wrong angle.

I don’t need to be concerned about creeping charlie because it is not a displacer in our yard. It doesn’t survive in the dense parts of the yard. There is no creeping charlie anywhere in our yard except in the turf grass areas and planted gardens residing in full sun. The native wildflowers, which grow thick and dense in the rest of the yard, crowd out the creeping charlie.

My new approach to creeping charlie will to let it grow in the turf grass while focusing on crowding it out in the sparsely planted gardens on the periphery of the turf grass lawn.

Emerald Ash Borer

Emerald ash borer has killed all of my ash trees.

Emerald ash borer (Agrilus planipennis) was discovered in Minnesota in 2009. Ever since, it has been expanding its area. Emerald ash borer is an invasive species of beetle that is a highly destructive pest of ash (Fraxinus) trees.

In 2017, Emerald ash borer was discovered about a mile from our property and more extensive infestations where found in 2019. I considered having our ash trees removed at that time but I had other more pressing concerns when the COVID pandemic hit in 2020. With the assistance of the resident woodpeckers, I made positive identification of Emerald ash borer infestations in our ash trees this spring (May 2022) but I had already had suspicions the previous fall.

We have an acre of land with 15-20 ash trees, all of which are infested and dying or are already dead. I requested estimates from several tree removal companies. I chose Davey Tree in South St Paul who will remove the ash trees in January.

Fortunately, only two ash trees are near our house. Neither provides significant shade on the house in the summer, so their loss will be minimal. The other remaining ash trees are clustered on south end of our property. They are largely screened from view by maple trees. However, their loss will be felt because the shaded they provided kept the common buckthorn (Rhamnus cathartica) at bay. I foresee increased effort upon my part to remove buckthorn from our property.

I’ll replace the two ash trees near the house with Kentucky coffeetrees (Gymnocladus dioicus) and the other ash trees with a mix of black walnut (Juglans nigra) and black cherry (Prunus serotina) trees. Black walnut will do well as I am frequently removing saplings from inopportune locations, most likely planted there by the resident gray squirrels. And there are numerous Kentucky coffeetrees in a county park located a few miles away. I was unable to find any black cherry trees while taking Lizzie for a walk through the neighborhood in search of them. I believe I have seen them around, I just don’t remember where I saw them. An article in Minnesota Conservation Volunteer, published by the Minnesota Department of Natural Resources (DNR), states that Minnesota is becoming more suitable for black cherry due to climate change.

I’m grateful none of our oak trees are impacted by pests or diseases. Oak trees provide all of the summer time shade on our house, keeping it significantly cooler during the summer. There is a noticeable difference in temperature between the unshaded and shaded portions of the front yard. On hot summer days, the unshaded portion is 10℉ warmer than the shaded portion. I’ve been keeping a close watch on our oak trees and have been diligently watering them during the drought we have been experiencing for the last two years. Our neighbors have an oak in their back yard that was killed by oak wilt. I intend on contacting Davey Tree to inquire with them what preventative steps I can take to protect our oak trees. I don’t want to lose them.

Siberian Squill (Scilla siberica)

One of the first plants to bloom in Spring is Siberian Squill (Scilla siberica). It’s a pretty flower scattered all over our yard.

Unfortunately, it is considered an invasive species. I have no hope of eliminating it from our property. To do so would require extensive remediation for which I have neither the time, nor money, nor the energy.

Garlic Mustard (Alliaria petiolata)

I enjoy discovering new plants in our yard. Since we purchased this property 12+ years ago, the diversity of plant life has noticably increased. This is partly due to our not using herbicides and just letting nature do its thing.

This has a generally positive consequence, with native species gaining a new foothold on our property. For instance, Impatiens capensis (Spotted Touch-Me-Not, Spotted Jewelweed) has spread from no plants when we first moved in to hundreds of plants spread across the property.

Unfortunately, we have encountered our share of invasive species. Some, like buckthorn, are fairly well known while others, such as Garlic Mustard (Alliaria petiolata), are not as well known by the general public.

Picture of Garlic Mustard — Garlic Mustard

I first learned that Garlic Mustard is an invasive species when I posted pictures of it to my Facebook page, asking others if they knew what the plant was. To my chagrin, my friend Jeffery F. identified it as Garlic Mustard (Alliaria petiolata).

He wrote:

Garlic Mustard (Alliaria petiolata) is a noxious weed (illegal to transport off of your property) and takes over forest floors, killing all plants around it with the chemicals it excretes (allelopathic plant) and outcompetes all the native plants and tree seedlings as well.

I swung into action the following weekend and removed all Garlic Mustard I could find on our property. I knew I had to act quickly because it would soon be flowering. Mustard plants produce hundreds of seeds and, if I waited, I ran the risk of spreading the seeds all over our yard.

Before:

After:

I filled two bags with garlic mustard plants.

Since that day in late April, I have checked periodically for any plants I may have missed. So far, it appears I got all of them.