How late glyphosate before crop emergence?

[Oat]

I have heard of people spraying at coleoptile stage (before 1st leaf has appeared), but is high risk and I'm not sure if I would risk it

 

[D14]

We have one agronomist that likes roundup in with pre ems and another that wont entertain it.

Seems like a bit overkill especially if the seedbeds have been worked. Maybe if your drilling into cover crops?

 

[Hampton]

They've had their feet wet most of the winter which hasn't helped but this is one field of the bean's
View attachment 952229

I know people who have applied 0.5l/ha glyphosate to beans that big to kill a sea of blackgrass

 

[Matt77]

I'd heard similar, which is one of the reasons I did what I did as it sounded like it "should" be OK

 

[choochter]

I do wonder if there is some residual effect, despite it being said that it is broken down on contact with the soil. It won’t be instantaneous breakdown and so I think very susceptible plants could be damaged as they push through.
I sprayed off spring barley infested ploughing in November and it stayed clean as a whistle right through till we drilled in March.

my experience a couple of years ago is that there seemed to be a residual effect with carrots

 

[ollie989898]

I've put glyphosate in with a pre-em before but wouldn't dare make the recommendation without viewing the crop first. I'd be very very hesitant to put it in if the crop is anywhere close to emergence.

 

[steveR]

Anybody any experience of applying glyphosate post drilling and had a problem due to it catching the emerging crop?
I have done a couple of acres of beet as a trial just before the seedlings break through the surface in a particularly weedy patch so I guess I’ll soon know but just wondered if folk had any experiences good or bad.
As herbicide options become ever more limited I reckon it could be a useful tool but obviously there is a trade off between going too early and missing a lot of small weeds and going too late and killing the crop. Personally I think it’s a waste of time the day after drilling.

Used to do it a lot on light land to take out cereals drilled as an anti blow cover crop, usually mixed with the pre-em herbicide. Also used to take out the stale seed bed when I drilled into plough and press, Mother Natures anti blow....

 

[DrWazzock]

I've put glyphosate in with a pre-em before but wouldn't dare make the recommendation without viewing the crop first. I'd be very very hesitant to put it in if the crop is anywhere close to emergence.

That seems to be the usual approach and is the safest. But for me it seems like a waste of chemical. Up to 1.5 litres of glyphosate the day after drilling with the pre ems isn't going to hit anything that it is likely to kill in a conventionally prepared seed bed. It won't kill most large weeds that the cultivations haven't killed.
But, wait 5 days or so and here we see a fair old flush of weeds at cotyledon, some even with a pair of true leaves before the crop itself emerges. For me, that's the time when the glyphosate has most potential to do some good, but there is a much bigger risk of damage to the crop if you get it wrong.
I do wonder if there is potential to get more out of glyphosate by leaving it as late as possible pre emergence of the crop, but at the same time I'm concerned that there could be some residual effect that damages the crop as it emerges if the glyphosate has hit ground say only the day before. This seems to be crop dependent. Some crops seem to be more sensitive than other to residual glyphosate.
My reason for raising this topic is because we are losing so many herbicide actives that we need to get maximum benefit from what is still allowed and if more intelligent use of timings can add something then we are all winners. Get it wrong though, and you can wipe out your own crop. I appreciate that so its not something to be done without extreme care and attention.

 

[ollie989898]

I know people who have applied 0.5l/ha glyphosate to beans that big to kill a sea of blackgrass

In theory, most grasses will be killed very very readily with glyphosate, broad leaved plants seem more tolerant of it.

 

[DrWazzock]

It would be really interesting to do a series of trials on doses and timings of glyphosate preemergence on a variety of crops to see what the effect was. Maybe it has been done.

 

[4course]

Iwas half thinking of applying gly either before or with the pre em but its so fecking cold nothing is growing other than the beans deepish sown which are starting upwards and not yet pre emd too windy ,the sp barley chitted and almost emerged hasnt any weeds grass or bl to be seen ( yet) maybe if the wind drops and it warms a tad before weekend might have another look at the beans

 

[Wigeon]

If it's rape then a dose about a week after full emergence usually does the trick and saves a world of bother.

Sorry, not that helpful to the OP I admit!

 

[Timbo1080]

Usually try to spray Pre-Ems with Glyphosate around 10+ days after drilling, or up until coleoptile sheath has been broken if near emergence in the Autumn, or later if I can get away with it, and have done for nearly 2 decades. Never had a problem. Sprayed some slotty spring wheat a couple of days ago with Glyphosate, where the wheat was well shooted in the open slot....Probably 10% at risk, but not particularly worried, but was a bit squeaky bum about it at the time though, as to whether i'd assessed the field emergence correctly that morning. Have sprayed winter barley at what i'd call "White sticks" in rows - In this case I asked the Agronomist to have a hasty look before I did....His comment was that "if it isn't green, don't worry".....He was right, but that did scare the pants off me. However, I did manage to spray off ALL Daikon Radish about 10 years ago, which was part of a CC mix, as it had literally just emerged by the time I had got there that evening. I will make a HUGE cock up soon, i'm sure, but the extra control has been well worth it so far.

 

[yellow belly]

Before spraying with pre em I would get down on hands and knees and look for very small black grass
5mm

no cereal will emerge in 5 days from 30 mm down
in current cold weather it could take more than 10 days for emergance
beans from 50 mm or deeper takes 2 weeks or more

a few years ago 2 weeks after drilling beans I saw a green haze of black grass but no beans emerged and regretted not spraying glyphosate we could use Avadex in those days

With small seeded shallow drilled crops be very carefull

 

[Flat 10]

Usually try to spray Pre-Ems with Glyphosate around 10+ days after drilling, or up until coleoptile sheath has been broken if near emergence in the Autumn, or later if I can get away with it, and have done for nearly 2 decades. Never had a problem. Sprayed some slotty spring wheat a couple of days ago with Glyphosate, where the wheat was well shooted in the open slot....Probably 10% at risk, but not particularly worried, but was a bit squeaky bum about it at the time though, as to whether i'd assessed the field emergence correctly that morning. Have sprayed winter barley at what i'd call "White sticks" in rows - In this case I asked the Agronomist to have a hasty look before I did....His comment was that "if it isn't green, don't worry".....He was right, but that did scare the pants off me. However, I did manage to spray off ALL Daikon Radish about 10 years ago, which was part of a CC mix, as it had literally just emerged by the time I had got there that evening. I will make a HUGE cock up soon, i'm sure, but the extra control has been well worth it so far.

Always nice to hear from someone who has done it. thanks

 

[czechmate]

Something I have sometimes wondered and it came up in conversation; does roundup “kill” the seeds on top?

 

[yellow belly]

Something I have sometimes wondered and it came up in conversation; does roundup “kill” the seeds on top?

No
if it did notill would be the only system as all other herbicides would not be needed

 

[yellow belly]

Spraying glyphosate today 13 days after drilling
barley and beans will be well over 16 day between drilling and emergence
but the frost will have also done the early germinating black grass it is very sensitive in its first week or so

 

[Brisel]

Something I have sometimes wondered and it came up in conversation; does roundup “kill” the seeds on top?

No. It needs green leaf to take it up. It won't kill anything dormant. You wouldn't want to give it a big dose at high water volume though.

 

[Flatlander]

I grow round up tolerant soybeans here and I can say without a doubt that it still checks the growth. Sprayed half a field and rain off for another week to find un sprayed beans were 4 inches taller and a darker colour. Even spraying before seeding will slow emergence by two or three days and a common rate is only 1/2 litre of ru per acre. Even during the growing season the occurrence of mn deficiency following heavy rain is more noticeable. Round up has changed farming here and was touted as the safest chemical ever but I’m sure it’s not without its long term effects.
I’ve sprayed post emergence with good results but don’t leave it to the last minute. It will give you a clean start for a crop to get started in.