[MAIPC] Glyphosate's effects on trees and soil microbia

[Marc Imlay]

Because we target the glyphosate very carefully the amount of glyphosate is
about 10-20% of broadcast treatment.

 

Marc Imlay, PhD, Chair, Biological control working Group Conservation
biologist, Park Ranger Office, Non-native Invasive Plant Control
coordinator.  <mailto:Marc.Imlay at pgparks.com> Marc.Imlay at pgparks.com

(301) 442-5657 cell  Natural and Historical Resources Division

The  Maryland-National   Capital   Park  and Planning Commission

 

 

 

From: MAIPC [mailto:maipc-bounces at lists.maipc.org] On Behalf Of HTI Gmail
Sent: Wednesday, October 18, 2017 11:07 AM
To: Ossi, Damien (DOEE) <damien.ossi at dc.gov>; MAIPC Listserve
(maipc at lists.maipc.org) <maipc at lists.maipc.org>
Subject: Re: [MAIPC] Glyphosate's effects on trees and soil microbia

 

Damien

Very prescient timing.  I am just now reading "The Hidden Half of Nature"
which is a good presentation of soil ecology for the layman.

I am impressed by the interaction among bacteria, fungi and plants in the
rhizosphere of plant roots.  The discussion of how the agrichemical culture
disrupts the effectiveness of microbe ecology (reducing the beneficial
microbes that consume plant exudates thus allowing the pathogenic microbes
to dominate) is pretty convincing.

While this is not a definitive argument against glyphosate, it does give
some credence to the premise of those concerned.  

The counter argument of course is that we have used glyphosate for years to
manage invasive species and the soil ecology seems to recover.  Also, I
would weigh the relative risks of allowing invasives to take over (with the
resulting impact of THEIR exudates on the soil ecology) vs. keeping them at
bay and maintaining the soil ecology that is decided that "should" be there.

I really think the issue is the long term relative risk of non treatment vs.
treatment.  Even if there are definitive data to demonstrate that glyphosate
harms the soil ecology, what is that impact relative to allowing a
monoculture of stiltgrass (or WLBG) develop?  We KNOW (I think?) these
invasives have extensive and long term impacts on soil ecology.

Kind of like oral contraceptives.  We know there are risks associated with
their use.  But, those risks are minuscule compared to the risks associated
with pregnancy and child birth. (used to work in maternal health).

Will follow this discussion with interest!  Thanks for bringing it up.



Regards,
 
Dewey Clark
Club Naturalist
Co-District Manager (PA)
Potomac Appalachian Trail Club
Maryland Master Naturalist

On 10/18/2017 9:17 AM, Ossi, Damien (DOEE) wrote:

I am trying to convince the land managers in my city (Greenbelt, MD) to
start managing the invasive plants on some of their land.  I am getting some
pushback from a community group that says there's proof that glyphosate will
kill or damage trees and soil biota.  I've been looking for published papers
that would support of refute their arguments, but have been unable to find
much. (I don't have access to JSTOR, BioOne, etc.)  

 

They are citing the following documents: 

 

(1) Pennsylvania Extension Service:  Tree roots absorb glyphosate; it has a
much longer half-life than when it is in the soil.  A single glyphosate
application results in ,persistent stunted leaf growth.
https://extension.psu.edu/use-glyphosate-with-care-near-trees

 

(2) Michigan Extension Service: Herbicides that touch the bark of mature,
healthy trees may be absorbed by the outer bark and negatively affect the
adjacent vascular tissue.
http://msue.anr.msu.edu/news/be_careful_where_you_spray_that_stuff

 

(3) Glyphosate interferes with the ability of tree roots to absorb
manganese, zinc, iron, and boron from the soil; resulting in root rot,
reduced cold hardiness, and reduced drought hardiness.
http://homeguides.sfgate.com/effect-glyphosate-tree-roots-29076.html

 

Does anyone have any resources that address these issues, or is there any
known comprehensive document that reviews and summarizes independent
research on the effects on glyphosate in forest ecosystems?

 

Thanks,

 

Damien

 

Damien P. Ossi

Wildlife Biologist

Fisheries and Wildlife Division

Department of Energy & Environment

Government of the District of Columbia

1200 First Street NE, 5th Floor

Washington, DC 20002

Desk: (202) 741-0840

Web: doee.dc.gov <http://www.doee.dc.gov/> 

 






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