| Previous digest | Subsequent digest |
Global Invasive Species Team listserve digest #062
Mon May 15 2000 - 14:31:13 PDT
--CONTENTS--
1. Bentazon (Basagran) on garlic mustard (Nationwide)
2. Fire and Berberis or Lonicera (MA, CT, NY)
3. News on GPS accuracy (Nationwide)
---------------------------------------
1. Bentazon (Basagran) on garlic mustard (Nationwide)
From: John Randall (jarandall(at)ucdavis.edu)
In Digest 60 Augusta Mazyck asked for more information about using the
herbicide bentazon (brand names Basagran, Basagran SG and Basagran T/O) on
garlic mustard (Alliaria petiolata). Vicki Nuzzo experimented with this
compound and briefly described her results in the garlic mustard Species Management Summary but
so far I have not been able to find others who have used it against garlic
mustard. I did, however, find more information on this herbicide: Bentazon
is selective against (will kill) most broadleaf plants and some sedges but
will not kill most grasses. It is primarily a contact herbicide, meaning
it kills or injures portions of the plant that it lands on and little
else. It blocks photosynthesis by binding with the D1 protein of the
photosystem II complex. This stops CO2 fixation and production of ATP and
NADPH2 which are needed for plant maintenance and growth. In most cases,
however, the plants are actually killed because the blockage in the
photosystem promotes formation of oxidized molecules that cause chain
reactions destroying chlorophyll, carotenoids and cellular membranes. This
mode of action is similar, but not identical, to that of atrazine, until a
few years ago one of the most widely used agricultural herbicides in the
world. Bentazon is slightly toxic to animals if ingested or absorbed
through skin or respiratory membranes. For comparison, the LD50's (dose at
which 50% of test animals die) for bentazon are lower (=more toxic) than
glyphosate (Roundup, Rodeo) but slightly higher (=less toxic) than
triclopyr (Garlon, Pathfinder). Bentazon's biggest drawback appears to be
that it is very soluble in water and does not bind to soil particles which
suggests a high potential for groundwater contamination. It has a short
half life and breaks down rapidly in soil (average half-life 20 days),
however, and estimates based on an EPA survey indicate it is found in
about 0.1% of rural drinking water wells nationwide although it is widely
used. It was not detected in any US community water systems nor was it
detected at concentrations above 0.02 mg/L in any well. Bentazon is
rapidly broken down in non-susceptible plants and has little effect on
germinating seeds. The brands Basagran SG and Basagran T/O are registered
for use in non-crops sites, roadways and other rights of way and thus can
be legally used in natural areas in at least some states. The labels state
that this herbicide should not be applied under sycamores or rhododendrons
and that it may kill trees and shrubs if applied to soil beneath their
canopies. It may also kill native broadleaf herbs if applied when they
are green and growing. The brand Basagran is registered for use only in
crops (soybeans, corn, sorghum rice [except CA], peanuts, beans, spearmint
and peppermint) and thus is not legal for use in natural areas except
under an experimental use permit or emergency use permit from the EPA.
Bottom line: it may be worth experimenting carefully with bentazon
(Basagran SG or Basagran T/O) for control of garlic mustard in areas with
native understory grasses but this compound is likely to kill native
broadleaf herbs if applied when they are active, and possibly some woody
plants if applied under their canopies.
---------------------------------------
2. Fire and Berberis or Lonicera (MA, CT, NY)
From: Tim Abbott (tabbott(at)tnc.org)
The Berkshire Taconic Landscape Program (MA, CT, NY) has Berberis and
Lonicera species to contend with and control by cutting and glyphosate
herbicide is currently our best option. Is there any research that
indicates that prescribed fire has been successfully used to kill these
species where they comprise between 65% and 100% cover in the forest
understory? Can you direct us to anyone who may have experience with
burning barberry and shrub honeysuckles?
---------------------------------------
3. News on GPS accuracy (Nationwide)
From: Barry Rice (bamrice(at)ucdavis.edu)
You may have noticed that your GPS unit is suddenly much more accurate.
This is because as of May 1, the Pentagon is no longer adding an error
offset to the satellite signals GPS units receive. (This offset is often
called "Selective Availability".) As such, you no longer need to obtain
differential corrections to obtain 10-20 meter accuracy for your GPS
units. Inexpensive, handheld GPS units are now much more accurate, and
GPS-based monitoring is more convenient and inexpensive than ever. Yay.
For higher accuracy (i.e. 1-3 meter), you will still need to obtain
correction data.
More information on this change can be obtained from the Interagency GPS
Executive Board web site at http://www.igeb.gov/
---------------------------------------------------------------