How does weed killer get INTO the plant (leaves? roots? stem? mechanism?)
After cutting a 500-yard long path through thick poison oak, I'm now
applying huge amounts of glyphosate-based Roundup weed killer to kill
remaining emergent plants left behind after the battle.
These constant skirmishes are depleting my Roundup, gallon by expensive
gallon (bought in concentrated bulk from Costco).
I'm spraying the stems, the ground, and the leaves ... but ... I wonder ...
what is the mechanism that allows UPTAKE of the glyphosate?
I looked up how weed killers kill, and can easily ascertain that
glyphosates mimick the natural EPSP Synthase needed as a catlyst for the
plant to create proteins ... but nothing I've found so far tells me how the
glyphosate is ABSORBED into the plant and WHERE it is best applied
(leaves?, stem?, roots?).
Mostly, I'm left with huge tangles of poison-oak stems ... so I ask ...
WHERE does weed killer get INTO the plant and how?
On Sun, 25 Apr 2010 17:06:15 +0000 (UTC), Elmo wrote:
This journal article implies only the leaves can uptake the glyphosate ...
both the underside and the upper side ... but HOW do they do that?
What is the mechanism of uptake?
Bear in mind, leaves act like a child drinks from a straw ... i.e., water
transpires OUT causing a vacuum which brings water and nutrients in from
the ROOTS ... but glyphosate isn't applied to the roots ... it's applied to
It's all very confusing ... if the leaves are transpiring OUTWARD, why
would they suck in the wet glyphosate? What's the mechanism to suck INWARD
water from the leaf?
From what I can gather, it's absorbed through foliage. Just like your
skin transpires, chemicals can be absorbed through it. Directions on
small spray bottle of Roundup that I have says spray on foliage and if
you accidentally spray on something you did not intend to, wash it off.
That would indicate less harm to plant if in soil.
There are better brush killers than roundup. Brush killers are absorbed
thru the leaves. They also can be applied to a fresh cut stump in a
concentrated form. I would be using Garlon instead of roundup. I would
apply it to the leaves a few days before I cut the plant down. When I cut
the plant down I might also paint some on the stump. I would then reapply
it to any regrowth from the roots every few weeks. The best time to use a
brush killer is when the plant is actively growing in the spring. I might
also buy a couple of goats to help with the regrowth.
Just thought I'd mention... I had heard applying too much poison can
sometimes make the poison less effective. I find some things hard to
believe but when it was explained to me I caught on. Some poisons, like
mentioned, rely on the plant to uptake the poison and spread it
throughout the plant including the roots. If the poison is mixed too
strong, it kills off the foliage before it has had time to get to the
roots. The top of the weed dies, then the roots send more foliage back
up again. Ahh, now I get it! FWIW
Had some difficult to kill poision ivy on a slope. definetely only
Tried roundup, it just stunted its growth
tried poision ivy killer, again stunted growth.
talked with a landscaper who would only kill the entire slope, there
were long term plantings there I didnt want to kill:(
came here and got EXCELLENT suggestion:)
mix roundup 50/50 with poision ivy killer. breaks feds law but it
I actually felt bad for the poision ivy, after being so dedicated it
looked bad 12 hours after spraying and was firmly dead in a week.
do note the dead stems etc can still make you itchy:(
so first let the poision ivy leaf out lushely again.
Then break federal law by mixing the chemicals, and wipe out your
poision ivy patch:)
Herbicides that are absorbed through the leaves can be rendered
ineffective if mixed to strongly. This is because of their systemic
nature. It takes time for the active ingredient to make it to the
roots. If excessive ingredients are present it just kills the leaves
and leaves the roots. Unfortunately the public demand was to have
instant results so lines of herbicides were placed on the market that
killed leaves and little else.
As I said the last time you posted, you'd get better control to spray
the plants _before_ cutting (while actively growing, of course) and let
it do it's work. It'll take a while, but it will do so.
Once you've cut it off, you're only application point is to individually
"paint" the stumps or wait for regrowth.
Same reason your fingers get all white and wrinkly when you soak them in
water...transpiration isn't the only process goin' on. Moisture on the
leaves is more accessible, I suppose, so it crosses cell membranes more
quickly than the moisture coming from the roots. The chemicals in
herbicides might do so more quickly...
Miracle grow fertilizer advertises it feeds thru the roots and leaves.
All herbicides say on the label dont mix. But I can assure you 50%
roundup 50% poision ivy KILLS poision ivy 100% effectively.
It will look BAD within hours:)
Couple of points to agree with and add. First, while Roundup can be
used to kill poison ivy, it's not the best choice. Look for products
labeled as brush killer. Another important factor is some of the
products available will not only kill existing vegetation, but also
prevent anything growing back for 4-6 months.
Second, if you use Roundup a lot, buying it at the big box stores or
local garden center is a big mistake. The absolute most expensive
choice is buying it pre-mixed. But even the concentrated mixes are
very expensive compared to what you can find online. A few years
back, I bought 2.5 gallons of Razor, which is glyphosate, same main
ingredient as Roundup, about 50% strength, for maybe $90 online.
You'd have spent several times that buying Roundup in any form at the
usual shops. None of the places I looked have even the concentrate at
anywhere near 50%.
On Mon, 26 Apr 2010 09:55:41 -0400, firstname.lastname@example.org:
A gallon of 50% will make 10 gallons of 5% mix which is plenty strong,
more than twice as strong as regular Roundup at 2%
I bought two refills of Super Roundup 50% each for a 1 gallon Roundup
pump sprayer to equal two refills. Dumped both into my two gallon
sprayer. Sprayed down some weeds out on the back lot and in about a
week they were brown.
On Apr 26, 9:55 am, email@example.com wrote:
At the time I was buying it, which was probably 6 years ago, HD didn't
have anything competitive in the local stores. Out of curiousity,
next time I'm in the store here, I'll check and see what they have.
Online they only have the super-concentrate, 50%, in half gallon for
$65. But even that could be a good choice, depending on how much you
use, etc. The real point is to find it highly concentrated and
figure out how much glyphosate you are getting for your dollar.
Unless you only have two weeds to kill, buying the ready mix stuff is
the worst deal ever.
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