Invasive Plant Guide

Towson University researchers in Maryland want your help tracking the spread of wavyleaf basketgrass.  Get more information and download their app at http://heron.towson.edu/wavyleaf/home/

Ottawa County parks in Michigan got their first goat herd to do some invasive plant clearing, http://www.mlive.com/news/grand-rapids/index.ssf/2014/05/goats_already_hard_at_work_in.html.

Use of goats (or other livestock) for controlling invasive plants isn’t a new technique, but it has been regaining popularity. My dad and co-author used a pair of goats to clear honeysuckle and blackberries along our driveway in North Carolina back in the early ’70s.  The goats eventually became the source for several strong tasting, stringy dinners.  It may have been better to let them continue munching honeysuckle!

In a massive study of soil and water samples from across the US, researchers frequently found low levels of glyphosate and its byproduct aminomethylphosphonic acid (AMPA). The concentrations are below levels considered harmful to humans and wildlife, but little information is available on possible effects of chronic low level concentrations of herbicides or pesticides.  In 2007, 180-185 million pounds of glyphosate were used in agriculture in the US .

W.A. Battaglin, M.T. Meyer, K.M. Kuivila, J.E. Dietze. 2014. Glyphosate and its degradation product AMPA occur frequently and widely in U.S. soils, surface water, groundwater, and precipitation. Journal of the American Water Resources Association, online 1 April

Don’t rush to plant following herbicide application according to a new article published in Restoration Ecology.  In pots in a greenhouse experiment sprayed with aminopyralid or picloram at the recommended rate, native forb and grass seeds from a dry NW grassland had lower seedling emergence and biomass than pots sprayed with water.   Even though the herbicides target broadleaf plants, grass seeds also suffered.  Not just seeding post-spraying but also seed recruitment from the seedbank would likely be affected by spraying.

Wagner, V. and Nelson, C.R. 2014. Herbicides can negatively affect seed performance in native plants. Restoration Ecology, online 07 April

Bushkiller vine, Cayratia japonica, has been found at 2 sites in Maryland, one in Anne Arundel Co. and the other in Baltimore (K. Kyde, MD DNR, 11/21/13).  These are the northernmost known occurrences of this plant. This vine looks a lot like Virginia creeper, but the leaflets are not all attached to a central point.  The lowermost leaflets occur in pairs.  As it name implies, bushkiller vine can overtop shrubs blocking light to the shrub’s leaves.  It climbs using tendrils.

Photo: Robert J. Richardson, North Carolina State University, Bugwood.org – See more at: http://www.invasive.org/browse/detail.cfm?imgnum=2105066#sthash.16vC8cJ1.dpuf

In a survey of 285 land managers in the U.S., researchers found that they spent nearly $4 million dollars per year on control of non-native Phragmites australis on 89,000 ha but few were happy with the results of their control efforts.  The  goals of most managers were to restore native flora and fauna and improve ecosystem function, but less than half felt they had met those goals.  Most organizations cited a lack of personnel and monetary constraints, along with re-invasion of Phragmites and difficulty in accessing populations.  The researchers found no correlation between amount spent on control and success in achieving management goals.

So does that mean that Phragmites control is a waste of time and money?  Or just that there needs to be more long-term funding of control and monitoring or new techniques developed for control?  Research on effects of Phragmites on natural systems shows mixed results.  Some studies show changes to benthic fauna and others show few changes. Phragmites is thought to alter nutrient cycling and some hydrological processes.  Different populations under different salinity levels and hydrological regimes may vary in their ecological effects.  Many control projects receive one-time funding and re-invasion can occur before any significant changes in flora, fauna or ecosystem processes have had time to take place.  Biological control is being investigated as a potential option, but because there are native strains of Phragmites australis, it could be difficult to find a biological control agent that doesn’t damage native populations.

The article ends with a cautionary note to land managers to assess what damage they think is occurring before spending money on control and to attempt to increase post-control monitoring.

Martin, L. J. and B. Blossey. 2013. The runaway weed: costs and failures of Phragmites australis management in the USA. Estuaries and Coasts, 36(3): 626-632.