Glyphosate… how long til rainfast?

[neilo]

Applying a little liquid sunshine to Spring Barley this afternoon, as some fields have a bit of greenery coming up and another has loads of greens/secondary tillers.

Just been once round the headland of a 17ac field and the heavens opened for half an hour. How many minutes does it take to be effective (2L/ha + conditioner)? Packed up and left 1800L of spray sat in the tank until the morning, but hey ho.

What’s the collective’s verdict on the field I finished an hour prior? Wait and see what happens, or re-spray tomorrow anyway?

 

[ploughman1963]

We had similar occur a couple of years ago just as the sprayer pulled out the field- I was amazed that we noticed no I’ll effects

 

[David.]

If I came and sprayed 360 on your prized lawn, would you be content that a shower would save it..
But seriously, if the spray went on a dry leaf, I'd bet it will be fine.

 

[Steevo]

Personally I'd say you'll be absolutely fine.....provided you have used the correct rate.

 

[neilo]

Thanks all. I will leave the field sprayed first… then complain on here if it hasn’t worked.

Combine due on October 1st at this rate.

 

[ollie989898]

Depends on the weeds/target I would say. Grass weeds- no issue at all. Anything else, expect varying degrees of success. Might pay to respray the headland if you are going out there anyway but I'd say you will be fine.

I had a farmer spray off an old pasture some years ago, including the docks. Contractor came, applied stiff rate of quite a posh formulation (not a 360) glyphosate, as he was driving out the field the heavens opened and it rained for a good few hours. I genuinely thought I'd have to send more product but every plant within the sprayed area died, even the (established) grand docks. I was gobsmacked.

 

[Farmer Roy]

There are many, many formulations of glyphosate

they all have different levels of active & they all vary in the various wetters & adjuvants included with them

Thus, how rain fast they are varies from one product to another

conditions prior to the rain event can also make a difference

anyway, read the label. That information is there . . .

 

[Farmer Roy]

Applying a little liquid sunshine to Spring Barley this afternoon, as some fields have a bit of greenery coming up and another has loads of greens/secondary tillers.

Just been once round the headland of a 17ac field and the heavens opened for half an hour. How many minutes does it take to be effective (2L/ha + conditioner)? Packed up and left 1800L of spray sat in the tank until the morning, but hey ho.

What’s the collective’s verdict on the field I finished an hour prior? Wait and see what happens, or re-spray tomorrow anyway?

you say 2l / ha

but of which glypho product ?

360, 450, 510 etc etc ??

there are lots of different glypho strengths & formulations ( well, there are here )

about the only place you’ll see 360 here now is in a 500 ml bottle in a hardware or gardening shop . . .

 

[neilo]

Sorry, a generic 360 product which, I’d suggest, is very much the mainstay over here. Water conditioner added, even to collected rainwater.
Conditions ideal before spraying, about 17 degrees with a dry leaf.

 

[Farmer Fin]

Did anyone notice the letter in the FW last week from the head of Bayer, saying the most important thing with glyphosate is the grams of active and not to cut rates by adding other products? Was he effectively saying that all their fancy expensive versions are unnecessary???

 

[Phil P]

As I’ve said in another thread previously, I once finished spraying the last couple of runs of glyphosate in a moderate shower. Field is the furthest from the yard so thought it’s worth a try rather than a return trip. Had a fairly substantial cover crop on it and 10 days later I couldn’t see any difference between where I’d started in the dry and finished in the rain as it all died off at the same time without issue. Will have been similar rate to you, maybe 2.5L/ha of 360.

 

[Farmer Roy]

The thing to remember is, different plants have different susceptibility to glyphosate.
Many variables, so some might be still killed if rain soon after application, but others might still survive. Tough broadleaves with waxy coatings on their leaves are very different to young fresh oat plants, for example . . .

 

[neilo]

Finished first thing this morning.

 

[ollie989898]

Did anyone notice the letter in the FW last week from the head of Bayer, saying the most important thing with glyphosate is the grams of active and not to cut rates by adding other products? Was he effectively saying that all their fancy expensive versions are unnecessary???

We are going back a while now but I have never added other products to a tank mix in an attempt to cut the application rates. I chose an application rate to suit the size/type of the targets at hand. This was fully supported by the label at the time (it may well not be any longer mind).

You cannot cut application rates of product merely by exchanging it for adjuvant, I do not know where people got that idea because it is flat out wrong and I cannot recall any manufacturer ever giving that technical advice.

Fancy versions of glyphosate all differ, but I can tell you with confidence the ones I have used were excellent and I would have more confidence in them than a lot of generic 360s.

If the higher doses I used to use were sufficient to kill everything in old permanent pasture, including docks, spear thistles and godknowswhat from established rootstock, then I do not see how manufacturers would justify spraying a few little weeds and cereal volunteers in stubbles at that same rate. Using products in this way is a bit unkind to the environment and hardly demonstrates good stewardship in their use, not to mention the cost involved.

 

[Farmer Fin]

We are going back a while now but I have never added other products to a tank mix in an attempt to cut the application rates. I chose an application rate to suit the size/type of the targets at hand. This was fully supported by the label at the time (it may well not be any longer mind).

You cannot cut application rates of product merely by exchanging it for adjuvant, I do not know where people got that idea because it is flat out wrong and I cannot recall any manufacturer ever giving that technical advice.

Fancy versions of glyphosate all differ, but I can tell you with confidence the ones I have used were excellent and I would have more confidence in them than a lot of generic 360s.

If the higher doses I used to use were sufficient to kill everything in old permanent pasture, including docks, spear thistles and godknowswhat from established rootstock, then I do not see how manufacturers would justify spraying a few little weeds and cereal volunteers in stubbles at that same rate. Using products in this way is a bit unkind to the environment and hardly demonstrates good stewardship in their use, not to mention the cost involved.

Never said they were not excellent, however I don’t believe they justify their price premium, as after all its grams of active that are important.

 

[ollie989898]

Never said they were not excellent, however I don’t believe they justify their price premium, as after all its grams of active that are important.

I would say there is a huge range of difference between competing products in terms of efficacy, speed of action and how wide the margins of 'still-going-to-work' are. I used to use a very posh granular formulation on some bigger arable areas for stubbles and never had any complaints about it, put it that way.

 

[serf]

Applying a little liquid sunshine to Spring Barley this afternoon, as some fields have a bit of greenery coming up and another has loads of greens/secondary tillers.

Just been once round the headland of a 17ac field and the heavens opened for half an hour. How many minutes does it take to be effective (2L/ha + conditioner)? Packed up and left 1800L of spray sat in the tank until the morning, but hey ho.

What’s the collective’s verdict on the field I finished an hour prior? Wait and see what happens, or re-spray tomorrow anyway?

Had same happen on some grass pee'd down after once round @ 3l ha , when rest was finished and died off looked like it had had hardly 1L on headland run !

"Yes it was low dose for grass anyway but it was shorterm grass and the res of field worked ok "

 

[Gong Farmer]

Did anyone notice the letter in the FW last week from the head of Bayer, saying the most important thing with glyphosate is the grams of active and not to cut rates by adding other products? Was he effectively saying that all their fancy expensive versions are unnecessary???

So the man from the chemical company was urging growers to use as much of their product as possible? Wow.

Rainfastness with glyphosate depends on how much rain falls and for how long. Even if it's washed off the leaf, it can run down the plant and do the job from there. In other words, rain needs to be enough to wash it all off the plant and into the soil, on a reasonably sized mature crop that's a lot of plant to by-pass.

 

[David.]

Wasn't there something about not going below 720g of active, so as not to encourage resistance?

 

[Gong Farmer]

Wasn't there something about not going below 720g of active, so as not to encourage resistance?

Is that the old 'low rates encourage resistance' chestnut again?