From: Comments THP 1-14-148MEN, application of herbicide.
Herbicide
applications alter the forest ecosystem on all trophic levels. On the
microbial level, growth and function are dramatically diminished
after herbicide applications. Both the essential bacteria which fix
nitrogen in soil, and the micorrhizal fungi which facilitate nutrient
uptake by a plant's root system are inhibited by most herbicides.
Bacteria and fungi have similar metabolic functions to higher plants,
and so are affected by herbicides in similar ways.
After
an herbicide application, the early successional plant species which
prevent erosion and nutrient leaching from soil die. Loss of their
stabilizing root structure leads to an increase in water movement
through the soil, increased nutrient loss, and increased erosion from
the spray site. In fact, soil nutrient loss from forest areas treated
with herbicides has been shown to be greater than loss after either
clearcutting or clearcutting followed by burning. The effect of
herbicide treatments on soil quality and nutrient uptake by plants is
compounded by the persistence of certain herbicides in soil. The
half life of the herbicide imazapyr in soil is calculated as 49.5
months,
MRC
should consider the news from San Francisco January
12, 2014:
Under the Natural Areas Program, UCSF,
which owns and manages most of Mt Sutro Forest, recently decided not
to use pesticides there. This may make it the only wild land in San
Francisco that is reliably free of pesticides.
http://sutroforest.com/2013/12/12/ucsf-no-pesticides-for-mount-sutro-forest/
IMAZAPYR
"Classified
as a Tier II (More Hazardous) chemical by the San Francisco
Department of the Environment, this is another pesticide used mainly
by NAP. In 2013, NAP accounted for 97% of the imazapyr used by SFRPD.
NAP started using Imazapyr even before the SF DoE had approved its
use. The main issues with it
are that plants push it out through their root system, so that it can
spread and affect other plants; it is very
persistent.
Its breakdown product is a neurotoxin."
According
to a BASF Safety Data Sheet from Europe, it’s “Harmful
to aquatic organisms, may cause long-term adverse effects in the
aquatic environment.”
However, a BASF Material Safety Data Sheet from the US says, “There
is a high probability that the product is not acutely harmful to
fish. There is a high probability that the product is not acutely
harmful to aquatic invertebrates. Acutely harmful for aquatic
plants.”
Imazapyr
is sold under the brand name of “Habitat” when it’s for Native
Plant Restoration. Its other trade names are slightly less benign:
Chopper. Stalker. Arsenal. Assault.
The 2005 Jackson Demonstration State Forest management plan states: Imazapyr
is sold under the trade names of Chopper or Arsenal in California.
This product can be applied by air, but primarily is applied by
low-volume hand-held spray equipment as a foliar, basal stem
treatment, cut stump treatment, tree injection, or frill. It controls
plant growth by preventing the synthesis of amino acids. Action is
slower than some other herbicides and can take several months or
longer. Imazapyr can remain active in the soil for 6 months to 2
years. It is strongly adsorbed in soil and usually found only in the
top few inches. Imazapyr is degraded in soils primarily by microbial
action. It is soluble in water. It has a low potential for leaching
into ground water. Like other herbicides the potential for movement
into streams via stormflow can be reduced by utilizing a
no-application streamside management zone.
The half-life of imazapyr
in water is about 4 days (SERA, 1999b).
Imazapyr
is practically nontoxic to fish and invertebrates (Table 1,
Ecotoxicological Categories). EPA has approved an aquatic label in
some states. Imazapyr is not expected to accumulate or build up in
aquatic animals (I.V. 1995). Imazapyr is considered practically
non-toxic to mammals and birds (Category IV, Table 1). Its toxicity
to bees is believed to be similar to mammals. Risk to non-target
plants may be slightly higher than other herbicides because of its
soil activity.
And from:
Agricultural Chemistry Research And Extension, Dept of Environmental
and Molecular Toxicology; Oregon State University; National
Institute of Health Services, Environmental Health Sciences Center -
Community Outreach Program, OSU-
For
Comparative purposes, the EPA categorizes pesticides by their short
term toxicity on a scale of 1 (most toxic) to 4 (least toxic). Most
undiluted imazapyr formulations are Toxicity Category 4. "Imazapyr may
be persistent in soils. Reported half-lives range from 14 days to 17
months. In forestry dissipation studies, reported values for the half
life of Imazapyr range from 14 – 44 days in forest litter, 19 –
34 days in forest soils, and 12 – 40 days on plants.”
“Water
soluble, it is highly mobile in soils, and can travel through soil
with water and enter groundwater. It can also move with runoff and
enter surface water. Forestry uses should be evaluated for potential
surface and groundwater contamination.”
“The
EPA advises, not to walk through freshly-sprayed vegetation. Do not
eat berries or mushrooms, or other edibles, or drink the water from
newly treated areas.”
PRACTICALLY NON-TOXIC
It’s water-soluble, and
moves through soil to get
into groundwater.
“Traces of imazapyr were detected
in the groundwater even 8 years after application,”
according to a study by scientists from the Swedish University of
Agricultural Sciences.
(Pest
Management Science, June 2004.) Full
report is incorporated by reference.
"The
long‐term fate of the herbicide imazapyr
[2‐(4‐isopropyl‐4‐methyl‐5‐oxo‐2‐imidazolin‐2‐yl)nicotinic
acid] applied to a Swedish railway embankment was studied. Imazapyr
was applied at 750 and 1500 g ha−1
by a spraying train used for full‐scale herbicide treatment
operations. Soil and groundwater were sampled twice a year for 8
years after application of the herbicide, and the dissipation of
imazapyr was studied by HPLC analysis of the residues in soil and
groundwater. A clean‐up procedure including solid‐phase
extraction was performed prior to detection by HPLC. Recoveries of
imazapyr from soil and water samples were 76–98% and 61–90%,
respectively, and detection levels were 0.003 mg kg−1
and 0.05 µg litre−1,
respectively. Sorption, desorption and microbial amount and activity
were also measured at the two locations. The organic matter content
correlated positively and the pH negatively to the adsorption of
imazapyr on soil, and increasing organic matter contents decreased
desorption. Apart from the 0–10‐cm top layers of both sites, the
microbial amount and activity were small. The main proportion of
imazapyr was found in the upper 30 cm of the soil, and degraded with
a half‐life in the range 67–144 days."
"Small amounts were
transported to lower soil layers and to the groundwater in proportion
to the amounts applied. Traces of imazapyr were detected in the
groundwater even 8 years after application. It was concluded that
environmental risks from the use of herbicides on railway embankments
could be reduced by including adsorption layers in the embankment
during their construction and by reducing the dose of the herbicide
used. Copyright © 2004 Society of Chemical Industry -
The Fate Of Imazapyr In A Swedish Railway Embankment - Source:
Pest Management Science, Volume 60, Number 6, June 2004, pp.
544-549"
While
the Swedish study is a broadcast spray scenario, that Imazapyr is pushed out
through the roots into the soil is known and is relevant.
What
is the environmental fate of the tree foods? Madrone berries,
manzanita berries, oak acorns, this must be considered if herbicides
are to be applied. The only other timeframe limitation is wet weather
and spring (sap flows). The
application of herbicides affects foraging for the NSO. With 11 NSO
activity centers in the plan, has this concern been considered by MRC
and CDFW?
In
fact, some plants actually push it out, so it gets into the tangled
roots below the soil and kills other plants. From the Nature
Conservancy’s Weed Control Methods handbook: “… imazapyr may be
actively exuded from the roots of legumes (such as mesquite), likely
as a defense mechanism by those plants… the
ability of imazapyr to move via intertwined root grafts
may therefore adversely affect the surrounding desirable vegetation
with little to no control of the target species.”
From:
Agricultural Chemistry Research And Extension, Dept of Environmental
and Molecular Toxicology; Oregon State University - National
Institute of Health Services, Environmental Health Sciences Center -
Community Outreach Program, OSU
For
Comparative purposes, EPA categorizes pesticides by their short term
toxicity on a scale of 1 (most toxic) to 4 (least toxic). Most
undiluted imazapyr formulations are Toxicity Category 4.
“May
be persistent in soils. Reported half-lives range from 14 days to 17
months. In forestry dissipation studies, reported values for the half
life of Imazapyr range from 14 – 44 days in forest litter, 19 –
34 days in forest soils, and 12 – 40 days on plants. Water soluble,
it is highly mobile in soils, and can travel through soil with water
and enter groundwater. It can also move with runoff and enter surface
water. Forestry uses should be evaluated for potential surface and
groundwater contamination.”
The
half-life of imazapyr in water is about 4 days (SERA, 1999b).
(JDSF 2005)
From:
CalEPPC 2003, Imazapyr: CalEPPC 2003, Considerations for the Control
of Invasive Plants - Imazapyr Wildlife Toxicity – Full report is
incorporated by reference.
Stalker,
Chopper, Arsenal, Habitat
?
Quail 8 day diet LC 50 >5000ppm
?
Duck 8 day diet LC 50 >5000ppm
?
Honey bees LD 50 >100 Mg/bee
?
Earth worm 14 day LC 50 >132.5ppm
Imazapyr
- Environmental Fate
?
Soil half life 25-142 days
?
Microbial Degradation
?
Water half life 2-3 days
?
Soil mobility 12-18 inches vertically/no lateral movement
So
we see that impacts to the food chain are inevitable. The chart above
is from the EPA and represents toxicity tests where 50 percent died in control groups. That is the legally allowable toxicity level for use. That 50 percent includes a 10 percent natural mortality in control groups. If more than 50 percent die, the active ingredient is not allowed for use.
Mendocino Redwood Company needs to end
herbicide use on it's ownership.
From
the IMAZAPYR Specimen Label
STUMP
AND CUT STEM TREATMENTS
Imazapyr
will control undesirable woody vegetation in forest management when
applied as a water solution to the cambium area of freshly-cut stump
surfaces or to cuts on the stem of the target woody vegetation.
Applications can be made at any time of the year except during
periods of heavy sap flow in the spring. Tree injection and cut stem
treatments are most effective in late summer and early fall. DO NOT
over-apply to cause run-off or puddling
of spray solution.
APPLICATION
WITH DILUTE SOLUTIONS:
For
cut stump treatments: Spray or brush the solution onto the cambium
area of the freshly cut stump surface. Thoroughly wet the entire
cambium area (the wood next to the bark of the stump).
For
tree injection treatments: Using standard injection equipment, apply
1 milliliter of solution at each injection site around the tree with
no more than one inch intervals between cut edges. Insure that the
injector completely penetrates the bark at each injection site.
For
frill or girdle treatments: Use a hatchet, machete or similar
implement to make cuts
through
the bark around the tree at intervals no more than two inches between
cut edges.
Spray
or brush mazapyr solution into each cut until thoroughly wet.
APPLICATION
WITH CONCENTRATED SOLUTIONS:
For
tree injection treatments: Using standard injection equipment, apply
1 milliliter of solution at each injection site. Make at least one
injection cut for every three inches of Diameter at Breast Height
(DBH) on the target tree. For example, a three inch DBH tree will
receive 1 injection
cut while a six inch DBH tree will receive 2 injection cuts. On trees
requiring more than
one injection site, place the injection cuts at approximately equal
intervals around the tree.
For
hack and squirt treatments: Use a hatchet, machete or similar
implement to make cuts
at
a downward angle completely through the bark and cambium at
approximately equal intervals around the tree. Make at least one cut
for every 3 inches of DBH on the target tree as described above, using a squirt
bottle, syringe, or similar device apply about 1 milliliter of
concentrate solution into each cut, ensuring that the solution does
not run out of the cut.
It is a violation of Federal law
to use this product in a manner inconsistent with its labeling.
Employ
People, Not Poisons
Tomas DiFiore
