Glyphosate

[simoh1490]

Does glyphosate have a useful shelf life, after which it loses its potency? 

 

I've sprayed an area of grass three times over a week and nothing has happened, the bottle is about three years old. Yes, I've watered the area first and yes, I've mixed it correctly, a super strong mix of 100ml per 6 litres of water - the target is a stubborn weed/grass that is growing out of control in a lawn of malay grass.

[drtreelove]

Shelf life should not be an issue. but give it more time to show results. It can take two weeks sometimes for yellowing to start.

 

A lot depends on the brand of glyphosate you are using, whether it has a built in surfactant or not, and another factor is the water you are using for the tank mix.

 

If it doesn't prove effective, try adding ammonium sulfate 21-0-0 to the tank mix.  The following is an excerpt from a Michigan State University publication. They recommend 17 lbs of the 21-0-0 to 100 gals of water. You can do the math for your spot sprayer mix. 

 

In order for Glyphosate to be effective
it needs to be absorbed into the plant.
In soft water Glyphosate has no problems in being absorbed,
however; in hard water Glyphosate will be "tied up"
and not be absorbed as readily.
This is known as "hard water antagonism".
Hard water contains high concentrations of the soluble salts, calcium (Ca++) and magnesium (Mg++).
When these are present in your spray water
the Glyphosate, which is negatively charged,
will combine with them to form Glyphosate-Magnesium
and Glyphosate-Calcium compounds.
These compounds are not as easily absorbed by the plant
and the result is poor uptake and poor weed control.

So how can growers increase the efficacy of
their Glyphosate treatments?
A common practice has been
to add a surfactant to the spray tank,
this allows the Glyphosate spray solution
to spread across the leaf surface better
and the result is greater absorption into the leaf.
Some Glyphosate products
now have the surfactant in them such as "Roundup Ultra".
Roundup Ultra does not solve the hard water antagonism problem by the addition of a surfactant though,
as the surfactant alone does not address this problem.

The hard water problem is best solved by
adding 17 pounds of ammonium sulfate per 100 gallons
to the spray water before the Glyphosate is added.

Urea - Ammonium Nitrate (28% liquid nitrogen)
will also improve the efficacy of Glyphosate,
but not as well a the Ammonium sulfate.

The addition of this compound to the spray water does two things.
First, the sulfate ions tie up the calcium and magnesium ions
by forming conjugate salts and
secondly, some of the Glyphosate ends up as
a Glyphosate-Ammonium compound
which some species of weeds preferentially absorb
into their leaf tissue over Glyphosate alone.

Reduced gallons of spray solution per acre will also have the effect of increasing the efficacy of the Glyphosate.
Fewer gallons of water equals fewer calcium and magnesium ions to tie up the Glyphosate.


 

[farmerjo]

As the DR says unless it's Fastmax,wait 10-14 days.

Also check how many hours for the product to be rain fast,if you had rain shortly after spraying it can affect it.

[simoh1490]

Indeed, but there's no rain to be had in this neck of the woods. I suspect it may be as the good Dr has indicated, we're in a hard water area so the rate of take up is probably reduced - in the absence of having any urea to hand I may just throw some 16-16-16 in the tank next time, that way, whatever doesn't get killed gets well fertilised and quickly too.  

[farmerjo]

I just did a 1st knockdown on a rice field yesterday,400ml of gylsophate mixed with 65 litres of dam(pond) water for 1 rai.

Will put the results on here when it takes effect.

 

[drtreelove]

urea 46-0-0 3kg packets are available at HomePro and by the kilo at the local nurseries where we are. 21-0-0 is harder to find, although if you're in Chiang Mai area by chance I know where it is available. The 16-16-16 is a different thing and may complicate the chemistry, or not provide the intended results, not sure.

 

If you use this method be sure to add the ammonium sulfate or urea to the water and agitate first before adding the glyphosate product. 

 

Growers take note; glyphosate by itself (or with the fertilizer adjuvant only) is not volatile and can be used in close proximity to crops and to water/fish. But round up products with surfactants can possibly volatilize into gaseous form and travel by air to contaminate adjacent plantings or water. 

 

For organic growers, hard chemistry herbicides like glyphosate are not organic program compatible. Use mechanical weed control or now there are new products becoming available that are suitable for spot spraying with contact herbicide like the attached label. The fatty acid concentrates are not systemic and only kill the foliar growth, not the root systems.  

 

 

CERTIS.docx

[simoh1490]

Many thanks doc.

[farmerjo]

On 20/3/2561 at 9:18 AM, farmerjo said:

I just did a 1st knockdown on a rice field yesterday,400ml of gylsophate mixed with 65 litres of dam(pond) water for 1 rai.

Will put the results on here when it takes effect.

 

This is what it looks like today.

 

 

[kickstart]

On 27/3/2561 at 12:52 PM, farmerjo said:

This is what it looks like today.

 

 

FJ

    Was that grass weed rice grass ,if so it made a good job.

Ps, now would be a good time for the subsoiler.