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Species recommendations (in priority order)

Garlic mustard, Alliaria petiolata

I believe garlic mustard should be one of our highest priority targets. It spreads in to the sort of shaded wooded areas that make up most of our conservation lands. It forms very dense stands that shade out spring ephemerals, the kind of rare natural beauty that our conservation lands are supposed to protect. Garlic mustard is quite attackable: it can be pulled by hand without herbicides (at least in its second year phase, where it is tall), it is an upland plant and thus does not need wetlands permits, and it so far has only a few defined invasion points in Acton conservation lands. Four of those invasions are in the Acton Arboretum, and the Friends of the Acton Arboretum have shown enthusiasm in wanting to provide volunteer time. It has been reported that it takes about 5 years of once-a-year pulling to remove a garlic mustard invasion.

Photos and more information about Garlic mustard (and controlling it) can be found here: http://www.nps.gov/plants/alien/fact/alpe1.htm

Japanese knotweed, Polygonum cuspidatum

Japanese knotweed is a problem in open areas, not in deep woods. It can occur either in wetlands or uplands. There are lot of occurrences in the US and elsewhere along roadsides. Knotweed is difficult to successfully control, but it can be done. The town of Acton has been battling knotweed along roadsides for some time now, and Dean Charter, director of municipal properties, has offered to use his crews & equipment on a stand of knotweed in Wetherbee conservation land that is near Rte 2.

I recommend we prioritize this particular action highly, in order to start gaining experience with using herbicides in this small & controlled area. I believe many of our invasions will require herbicides to successfully control, but the use of herbicides requires caution. My understanding is that we will need both land stewardship committee and conservation commission approval before using herbicides on conservation lands.

One land steward, Gigi Hopkins, has been enthusiastically battling the knotweed at Wetherbee conservation area for a few years now, in a small area between the yellow loop trail and Rte 2. Her desire to do what it takes to remove the plant remains high, but her lack of success in actually removing the stuff has led the two of us to talk with Dean about doing the spraying. A plan in progress is here:

http://www.snyder-grant.org/Jim/Plants/invasives/WetherbeePoCu.html

This plan needs some updating because of new information about the timing of knotweed treatment that I learned at a knotweed control workshop offered by the US Fish & Wildlife Service on April 29, 2006. Fall treatments are better for knotweed because the plants will move the herbicide to their root system then. I intend to bring this plan to Land Stewardship and Conservation Commission review as soon as it is rewritten.

Having a demonstrably successful method for dealing with Japanese knotweed would also allow us to address the invasion that is taking over most of the Acton Assabet Canoe Launch. This would also be an important chance for public education, since the Canoe Launch is so visible right next to Rte 62.

[2006 update (needs more details] This patch was treated by Dean's crew in teh Fall of 2006. AN excellent die-back. He and I both anticipate the need for future treatment, but the initial results were excellent] 

Oriental, Asian or Asiatic Bittersweet, Celastrus orbiculatus

Oriental bittersweet is the climbing and strangling vine that is bringing down many trees in the US and elsewhere. Bittersweet is ubiquitous and hard to remove – it will be on our our conservation lands for the foreseeable future. I am only placing it this high on the priority list because I think we have an opportunity to save many fine trees by organizing efforts to regularly unstrangle trees that are being brought down. The manual technique is straightforward – pull vines off trees, cutting if necessary, and pulling roots out of the ground where possible. It’s a fine task for a variety of ages. I’d like to locate a group that is willing to start taking this on for the vast invasion in Nagog Hill, surrounding the trails between the Grassy Pond parking lot entrance and the Hybid farm entrance. Perhaps a scout troop? If we could get this going, it would make a fine model for elsewhere. Other large invasions at Guggins or Nashoba brook, for example, could use a similar approach. I’d like to find out if such an approach can work, since I think many invasions will respond to steady volunteer labor for a few years.

[2006 update: The Nagog patch of climbing bittersweet has been cut near ground level by Joan Cirillo, Nagog steward, with help from her friend John. Certain areas were covered quite thoroughly, and other areas are waiting for future treatment].

Purple loosestrife, Lythrum salicaria

This may be the most well-recognized invasive plant in the region, as it forms vast wavy stands of purple in our sunny wetlands, many visible from roads. The only reasonable hope of controlling purple loosestrife in the foreseeable future is via biological controls. Connecticut has a very successful program involving Galerucella beetles, that has been going on for over 10 years, run from the IPM program at UConn Storrs. Please see http://www.hort.uconn.edu/Ipm/ipmbio.htm for details and many helpful links. There is a 10+ acre invasion in the Acton Water District land adjacent to Guggins Brook that might be a fine starting point. An alternative treatment for loosestrife, involving herbicides, would be inappropriate in water so near town wells. An action involving biological controls will require some complex logistics to get started – education, permissions, locating funding, finding volunteer ‘beetle farmers’ etc. But this also promises a tremendous educational opportunity about invasives and biological controls, and I’d like us to start moving on this direction soon, learning as much as possible from the Connecticut experience.

[2006 update: Much loosestrife was cut and bagged at the Morrison Farm site, primarily by Gigi Hopkins. Gigi also researched earlier Acton action against loosestrife via Galerucella beetle releases. Her update should be made a part of this report] 

Other plant species (from chart)

I think that the other invasive species are either too well-established and with no successful treatment technique available; or are spreading so slowly that they do not present an urgent risk. I think that some parcel-specific actions are quite reasonable for some of these species, as time and enthusiasm permit.

Any small, isolated invasions that can be treated by pulling or cutting, without needing wetlands permits or herbicides, are good targets for interested land stewards or other volunteers. Examples can be seen by looking for invasions marked with a ‘hyphen’ in the invasions chart. For example, Japanese Barberry in Stoneymeade or Will’s Hole, or Burning Bush most anywhere except for the gigantic invasion on Great Hill.

[2006 update: Nan Millett has pulled many honeysuckle plants from Stoneymeade]

With some species, I need to do more research before making a recommendation about priorities. Some examples: Yellow Iris is spreading in the Arboretum, but is it spreading elsewhere? Most of my surveys have been on trails – this will require a stream-oriented survey. And what is a successful treatment strategy? Some literature suggests digging out the entire plant will work. Yellow Iris is nearly always in the wetlands zone, often directly underwater. How complex will the wetlands permitting issues be to work out?

Other plant species (not in chart)

The complete list of invasive plants causing problems in Massachusetts is much longer than the 16 in the invasives chart above. There are more than 100 species on the working list from the Invasive Plant Atlas of New England: http://invasives.eeb.uconn.edu/ipane/ipanespecies/current_inv.htm . And, there are also more than 100 species on the list of banned invasive plants recently released by the Massachusetts Department of Agricultural Resources: http://www.mass.gov/agr/farmproducts/proposed_prohibited_plant_list_v12-12-05.htm

As more invasive plant species are identified in Acton conservation lands, they may be prioritized higher than these already in the chart. New invasions that have not spread far are some of the best to focus on, because of the higher chance of actually eradicating them. “Early detection and rapid response” is one the highest priorities of the National Invasive Species Council. (see for example http://www.invasivespeciesinfo.gov/toolkit/detect.shtml )

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