Arboretum  - Alliaria petiolata (Garlic Mustard)

Date: 02006 May 25         Time: 9AM - 12AM

Conservation Area: Acton Arboretum

Workers: Jim Snyder-Grant

Location (description) Woods near end of Wood Lane.

Location (Coordinates): 42° 28.79'N, 71° 25.88'W (WGS84/NAD83 - from Topozone map)

Target Species (Latin): Alliaria petiolata     Target Species (Common): Garlic Mustard

Permissions: Written permission (via email May 23, 2006 1:14 PM) from Tom Tidman, Acton Natural Resources Director.

Wetlands: No  Herbicides: No

Summary of Plan: Verify location and extent of A. petiolata invasions in the Arboretum, and pull garlic mustard plants from Arboretum.

Reference to larger plan: None yet. .This action jumped out at me as I was surveying the Arboretum invasives, and starting to write a general invasives plan for Acton conservation areas. Garlic mustard seemed like a good plant to start with: easy to pull, requires no herbicides, has significant risk of spreading into shaded woods, and currently known invasions on Acton lands are still contained & look managable with only a few or one volunteer.

Survey (or re-survey) results: Primary invasion at end of Wood Lane was much more extensive than I thought - extended into Arboretum woods southwest of end of Wood Lane in an area approximately 50 feet wide and 40 feet deep.  Reviewed other invasions at end of two trails leading to houses on Wood Lane from Arboretum trails. First   invasion was very localized, right near woods edge to lawn. Second invasion was quite extensive, apparently on private property. Found another invasion in internal Arboretum meadow. Perhaps 100 plants, in a 10 foot by 30 foot area. There were other plants surviving near and among the Garlic mustard, but the thickest clumps were mostly monocultural. Other plant species included poison Ivy, Virginia creeper, wild geraniums, and other spring ephemerals I could not ID. Tree cover was mostly pine, with some oak. Soil was a bit sandy, relatively dry. Like most Acton conservation lands, this was re-forested agricultural land - two stone walls intersected at right angles near the invasion. 

Results: Bagged 2180 plants, filled 5 garbage bags, in primary invasion area.  Many thick stands. Initially started to pull first year plants as well (basal rosettes) but this was difficult and slow.  Picking second year plants was fast and easy - pulling by main stem brought up most or all of the roots.  Since pulling A. petiolata is reported to be a 5-year process, it seemed fine to concentrate on second-year, easy-to-pick plants each time. Walked edges of invasion, found areas with no invasion - this one seems to be moving steadily, but slowly. Reports are that seeds can be carried by rodents and deer, so we may find it deeper, but so far, so good. By end of time, second-year plants were beginning to be hard to find, but I was still finding a few more of them when I stopped. Left phone message for Tom Tidman requesting his crew remove & dispose of bags (trash, NOT COMPOST). Did not attempt to pick plants at other invasion areas.

Next Steps (roughly in priority order):

  1. Before seeding this season: Pull stand in internal meadow - Significant risk of spreading from there.
  2. [this season or next - & remember it's a multi-year effort]: ID owner of private land, offer to pull garlic mustard (and do so)
  3. This season or next: .Remove the other, smaller invasion
  4. Next season: re-pull second-year plants in all areas (Repeat for 5 years)

Lessons Learned: