I live in Leaside and this invasive weed is encroaching on to my garden from my neighbour’s backyard. I would like to know the name of this weed, so I ask for your help.
Thank you.
Thank you for consulting Toronto Master Gardeners with your question.
Invasive plants are certainly an issue for today’s gardener. Many invasive species used to be sold at nurseries, and some still are. In some cases, what is an attractive garden plant to one person is an invasive weed to another. Looking at the photo you sent, I actually see two potentially invasive plants. I’m not sure which of the 2 plants you were concerned about but both of them are potential problems in your garden and your neighbour’s. The ground cover is periwinkle (Vinca minor), and I believe that the small tree is a young Tree of heaven (Ailanthus altissima) sapling. The photo is not quite clear enough to make a definite identification of the tree. The following link is to a previous response regarding Tree of heaven, its identification and eradication:
https://www.torontomastergardeners.ca/askagardener/dont-know-the-type-of-tree/
Note, in particular the internal link in the response to a photo of a seedling tree. Sometimes it can be difficult to distinguish the seedlings of Ailanthus from Staghorn sumac (Rhus typhina). The leaflet margins of Ailanthus are smooth compared to the toothed edges of the sumac. As well, the leaflets have a small, protruding cusp at the base. I think I see this in your photo but I am not certain. A feature unique to the sumac is its fuzzy coating on the young stems and branches. If the seed has come in from your neighbour’s yard, you may be able to identify the adult tree specimen definitively. Both species should be in flower now, which makes it a little easier. The following article gives several clues to distinguish the two trees from one another:
https://bygl.osu.edu/node/1346
Once you have determined that the sapling is, indeed, Tree of heaven, you should remove it. These trees are very prolific, spreading by both seed and their aggressive root systems. The smaller they are, the easier they are to remove. You will need to dig out the root system, making sure to leave no root fragments. If any are left in the ground, you will need to dig out more small seedlings next spring. Make sure to dispose of the plant material in the City green waste, not in your compost.
Periwinkle is a much used ground cover in Toronto gardens. Unfortunately, it, too is considered to be an invasive species. Periwinkle spreads easily via underground stolons, and if planted anywhere near a park or wild area, it can take over vast swaths of ground, choking out native species. As attractive as it can be within cultivated spaces, it can also become a “garden thug” if it is not very carefully controlled. If you decide to leave it in your garden, watch it closely and pull it back to keep excess growth in check. If you decide to remove it, you can pull it out quite easily. You may need to go at it a few times this season, and possibly weed out some residual growth again next spring. Again, do not dispose of the dug up plant material in the compost. Please refer to the following article regarding invasive periwinkle:
http://www.invadingspecies.com/invasive-ground-covers/
Best of luck with the removal of these invasive plants!