Multiflora Rose in Point Pleasant Park, Halifax

I had highlighted this issue earler for Waye Mason, the councillor for the District 7 and a member of the Point Pleasant Park Advisory Committee.

Tracks and Waypoints. Click on image for larger version Six of the first 29 Waypoints are for particular plants or features other than R. multiflora (Nos 3, 10, 13. 15, 18, 22). For the subsequent sequence (30-46) there are no nos 30, 39, 40. So in total 23 + 14 = 37 sites of multiflora rose are identified. Tow more were added July 18 (WP 49 and 50; no nos 47, 48), bring the total to 39 sites. Some of these sites have only single plants or clumps of plants, others have several but in close proximity.

To provide better information on the status of Rosa multiflora in Point Pleasant Park, I conducted a quick survey while the plant was close to full bloom when it is most obvious.

On Monday July 11, 2016, I surveyed approx 3.5 km of roads and trails. Rosa multiflora was just at or just past peak flowering and easy to spot. I found it at 23 sites. On July 14 and 15, I surveyed an additional approx 2.5 km and found it at 14 sites, and a few shorter routes on July 18 and 20. Some sites have more than 1 plant or clump but they are in close proximity. I have undoubtedly missed a few.

Overall Rosa multiflora is more numerous on outer roads or trails than deeper into the park, and there are concentrations at particular sites that have large open areas such as at Fort Ogilve and the Cambridge Battery and on Cable Road down to the pumping station. Paths which are narrow and quite closed have few or none. Jeremy Lunholme says that there has been R. multiflora by the pumping station for some time. That site could well be the initial nucleus for spread of R. multiflora.

Overall there are many more plants than I had expected based on casual observations over the last several years, and there are a few areas with exceptionally high concentrations, most notably at Fort Ogilve. It would clearly be more work to cut back existing plants than I had suggested might be the case before conducting the survey. (View Letter)

I believe R. multiflora in PPP could still be controlled at this point. If concentrated efforts to do so have to delayed, existing plants should be cut back ASAP so that they are not allowed to fruit (or if fruit has set, so that fruit does not mature) which will reduce dissemination by birds. Many of the existing plants are growing aggressively and will be much more difficult to cut back in another year.

My suggestion is to cut all plants back by the end of July to stop them producing fruit. I suggest doing this before the end of July as possible because they are highly visible right now and while some fruits have set, they are not mature. Ideally plants would be cut back and the roots dug or pulled out (with mechanical help) and/or glyphosate applied to cut bases of the plant (only to the base, not to the surrounding soil). However, simply cutting them back now will stop the production of fruit and the complete removal could be conducted later, e.g. in September. (Please consult professional horticulturalist or an invasive plant specialists for details about use of glyphosate.)

Hemlock Walk, no R. mutiflora

The really dense patches, e.g. at Fort Ogilve, would require a major effort to eradicate. Another approach could be to begin with the sections of trails and roads that have very few Rosa multiflora now and eradicate those first, with consistent follow-up; and then attack as possible the sites with heavy concentrations. Even if the latter cannot be controlled, it should still be possible with relatively little effort (but with vigilance) to keep it out of routes where there are currently few plants (see map above) and thereby maintain more authentic Acadian forest vegetation over a large part of the park (re: PPP Management Plan).

Those are my thoughts. Please discuss strategies with Peter Duinker, Jeremy Lundholm (both of whom have been involved in management and/or research on PPP vegetation) and others as well.

For each site I prepared a short video and photos which I have posted on Google photos. You may have to sign in as a Google User. When you open the first photo, click on the "i" (information) symbol at the top right and it will bring up information about the photo to the right, including for most photos the location in Google Maps. Those locations could be off 10 m+; the GPX for waypoints obtained with a Garmin GPS should give the locations with more accuracy. Download GPX files with waypoints: WP 1-29 and WP 31-46 and WP 49, 50 (ignore #48).