PS 62-77 - Effect of herbicide treatments on germination of Japanese climbing fern spores and survival of fern gametophytes

Thursday, August 11, 2011
Exhibit Hall 3, Austin Convention Center
Jennifer L. Ulrich1, Samantha N. Miller1, Kimberly K. Bohn2, Mack Thetford3 and E. Corrie Pieterson4, (1)School of Natural Resources and Environment, University of Florida, Gainesville, FL, (2)School of Forest Resources and Conservation, University of Florida, Milton, FL, (3)West Florida Research and Education Center, University of Florida, Milton, FL, (4)School of Forest Resources and Conservation, University of Florida, Gainesville, FL

Lygodium japonicum (Japanese climbing fern) is a well-established exotic, invasive vine that has become a problem in a variety of forests in the southeastern United States.  Typically starting as a few scattered individuals, invasions of Japanese climbing fern can escalate into dense, tangled masses that overtop trees, smother understory vegetation, and alter fire behavior.  Invasions are especially problematic in plantations managed for pine straw as pine straw bales may serve as vectors for L. japonicum dispersal.  Due to the economic implications of L. japonicum invasion, research on this vine has primarily focused on control.  Complete eradication may be best achieved through strategic herbicide application throughout the plant’s life cycle.  In this study, the effects of herbicides with different modes of action were evaluated for their efficacy in controlling L. japonicum spore germination and sporophyte development.  Pots of two native, sterilized soils (loamy clay sand, loamy sand) were inoculated with L. japonicum spores and treated with 11 herbicides at three rates to determine which showed the most potential for controlling L. japonicum during early stages of its life cycle.  Each treatment was replicated 10 times and numbers of pots with gametophyte development were recorded weekly for 13 weeks following herbicide application.


Preliminary results indicate that spore germination varied among herbicide treatments.  Most of the herbicide treatments, regardless of concentration, suppressed germination with the exception of glyphosate and aminopyralid.  In these two cases, all treatments in pots containing loamy sand showed gametophyte growth after seven weeks.  It is unclear why glyphosate and aminopyralid failed to inhibit spore germination since herbicides with similar modes of action (e.g. metsulfuron methyl, sulfometuron, imazapyr) were successful.  One possible explanation may be the fact that surfactant was included in the particular brand of glyphosate used, which may have acted as a confounding factor.  Future work will include a replication of this study to assess additional variables (e.g. surfactant-only treatments) and to evaluate herbicide efficacy across a range of soil substrates.

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