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

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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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