WHERE does weed killer get INTO the plant (leaves? roots? stem? mechanism?)

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?

Reply to
Elmo
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This journal article implies only the leaves can uptake the glyphosate ... both the underside and the upper side ... but HOW do they do that?

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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 the leaves.

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?

Reply to
Elmo

Spray vegetation killers like Roundup contain glyphosate and a toxic surfactant. The surfactant helps spread the glyphosate on the plants' exterior for maximum effect. Granulated weed killers work systemically from the root. It's important not to saturate the ground when using a spray vegetation killer around vegetation you don't want destroyed because it can easily leech into the soil and also become a systemic poison for wanted vegetation. So a fine spray just enough to dampen the vegetation is all that is needed with glyphosate-based spray vegetation control. I always mix 2 a two gallon sprayer with concentrate Roundup refills each year. These are designed to refill your Roundup 1 gallon pump sprayer. My sprayer is capable of delivering a fine mist, coarse spray or stream and the wand can be held low just above the target vegetation. Be sure to spray on a calm day or in the morning when wind is usually calm.

If you are using a lawn weed spray that just kills weeds be sure to wait for the weeds to emerge as this spray also acts upon the surface of the weed. Make sure you plan the spray so that it does not rain for

2 days so the chemicals have time to get absorbed. This is also true for vegetation killer sprays regardless of what the manufacturer guaranties. Finally keep lawn weed spray away from flowers/flowering plants and vegetables.
Reply to
Jeff The Drunk

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.

Reply to
Frank

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.

Reply to
Pat

"This product moves through the plant from the point of foliage"

Osmosis.

"Annual weeds are easiest to control when they are small. Best control of most perennial weeds is obtained when treatment is made at late growth stages approaching maturity. Refer to the =93ANNUAL WEEDS=94, =93PERENNIAL WEEDS= =94 and =93WOODY BRUSH AND TREES RATE TABLES=94 for recommendations for specific weeds."

"For best results, spray coverage should be uniform and complete. Do not spray weed foliage to the point of runoff."

"FOR PRODUCT INFORMATION OR ASSISTANCE IN USING THIS PRODUCT, CALL TOLL-FREE,

1-800-332-3111.
  1. IN CASE OF AN EMERGENCY INVOLVING THIS HERBICIDE PRODUCT, OR FOR MEDICAL ASSISTANCE, CALL COLLECT, DAY OR NIGHT, (314)-694-4000."
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- gpsman

Reply to
gpsman

That's confusing toxicity of the surfactant with effectiveness as the herbicidal agent--it isn't effective at all as part of the herbicide; it's purpose is simply to serve as a surfactant to counteract surface tension of water and wet the foliage thereby promoting takeup.

...

Glyphosate breaks down and/or attaches very quickly in the soil which renders it ineffective. Also, since its action is only via enzyme interaction at active growing points within the plant it is not, therefore, effective as a pre-emergent herbicide.

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Reply to
dpb

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Reply to
[SMF]

osmosis

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.

--

Reply to
dpb

As others said its the leaves, and if all you have are leafless stumps you are wasting the roundup spraying, dont the roundup instructions state this, to spray leaves, then it must be left to do its jobs which takes maybe weeks, or its not dead.

Reply to
ransley

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

Reply to
Tony

age

=EF=BF=BDI would

Had some difficult to kill poision ivy on a slope. definetely only spray leaves

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 WORKS

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:)

Reply to
hallerb

But what is the mechanism that makes leaves "intake" (absorb, adsorb, injest, osmosis, etc.) the poison.

Why would a leaf, which is an excretion organ of the plant for liquids (transpiration) and gases (outgassing) ... why would that outgassing leaf INTAKE the poison?

The water comes up the roots and out the leaves. Why would the leaves intake the liquid poison?

Reply to
Elmo

"It is absorbed through foliage and translocated to growing points."

But, WHY does a plant absorb the poison when the plant normally doens't absorb water from its leaves.

IIRC, a plant absorbs water from the roots and transpires that water out the leaves so that nutrients flow up and sugars manufactured by the leaf flow down, with oxygen given off as a waste byproduct.

What I don't understand, if we can give a leaf a personality, is why the leaf bothers to absorb the wet chemical. What is that mechanism that makes the leaf want to absorb the poison.

Someone said osmosis, which might be right ... in that the concentration of the glyphosate is greater on the outside of the leaf than on the inside and the cell membranes allow the stuff through ... maybe it's that simple. Maybe not.

That's why I'm asking.

Reply to
Elmo

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Reply to
Elmo

I noticed some mixes of roundup arent' allowed to be sold in California.

What's the federal law that's being "broken" by mixing stuff?

Reply to
Elmo

e

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.

Jimmie

Reply to
JIMMIE

Some large trees in foggy costal areas get their water from the air through their leaves. This was explained in a National Geographic documentary on the costal area between Northern California and Oregon. The molecules of poisons contained in weed and vegetation killers travel the same route as chemicals in the leaves dispersed through the plant after photosynthesis occurs in the leaves .

Reply to
Jeff The Drunk

They also take in, they breath so poison enters through the leaf and affects the whole plant root and all.

Reply to
ransley

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