Longevity of autumn residuals

[robs1]

We applied avadex and generic liberator at full rate during the first ten days of October, due to rain most days since the crop isn't worth keeping, we want to put some grass in some bits and possibly some of the sfi options, obviously neither probably going to get drilled till beginning of April, will the sprays damage the seed still ? It will be DD, it won't get worked at all, I would rather not drill than disturb the seed bank.

 

[jessop123]

I think I would be a bit nervous as it won't be cultivated

 

[Northern territory]

We applied avadex and generic liberator at full rate during the first ten days of October, due to rain most days since the crop isn't worth keeping, we want to put some grass in some bits and possibly some of the sfi options, obviously neither probably going to get drilled till beginning of April, will the sprays damage the seed still ? It will be DD, it won't get worked at all, I would rather not drill than disturb the seed bank.

Avadex has a half life of 3 months compared to flufenacet which is 20 days. Probably a bit dodgy although it has been extremely wet.

 

[T Hectares]

I would be nervous without a shallow cultivation, which won’t disturb the seed profile

 

[solo]

I’m sure I read a very interesting article on active ingredient half life last year. I haven’t been able to find it again. Perhaps it was research done by NIAB / TAG If you’re a member?

 

[Brisel]

The longevity of residuals will vary. Something applied mid September will break down faster than the same dose applied in November when UV radiation and temperature levels are lower.

 

[Clive]

residuals hang about a LOT longer than most realise

in fact i would go as far as it say that maybe a very big % of OSR failures blamed on CSFB are more down to the combination of previous crop SU’s and DD

 

[Pan mixer]

On the Avadex bag it says do not apply in the autumn before sowing grass the following autumn iirc. Certainly good advice over here in the dry years, I had a big failure of grass one year by ignoring this.

However it has been so moist of late I wonder how much is really left this year?

 

[Northern territory]

residuals hang about a LOT longer than most realise

in fact i would go as far as it say that maybe as big % of OSR failures blamed on CSFB are more down to the combination of previous crop SU’s abd DD

Went to a meeting the other day about this and it was quite interesting that some spring su’s hang about a lot longer than others. They had a really good photo of a rape crop where the headlands had been sprayed in the previous crop. Wiped it all out on the headlands and middle of the field fine.

 

[David.]

I have certainly had stubble turnips damaged by SU products applied in spring, to the preceding w.barley.
Not happened since stopped using them in prior crop.

 

[Northern territory]

Found this interesting

 

[farmerfred86]

We applied avadex and generic liberator at full rate during the first ten days of October, due to rain most days since the crop isn't worth keeping, we want to put some grass in some bits and possibly some of the sfi options, obviously neither probably going to get drilled till beginning of April, will the sprays damage the seed still ? It will be DD, it won't get worked at all, I would rather not drill than disturb the seed bank.

I asked Gowan recently about the persistence of avadex... they told me they test avadex by planting oats and monitor the effects which can be seen up to a year!

 

[robs1]

I asked Gowan recently about the persistence of avadex... they told me they test avadex by planting oats and monitor the effects which can be seen up to a year!

Perhaps I will use some of the area as a test patch, and perhaps even scratch a bit to see if any grass weeds come up. To be fair it is very active on oats, the area we used it on last year which was the first time we had ever used it had plenty of BG which germinated in late Feb/ march but not one wild oat despite it being in spring oats the year before

 

[Bignor Farmer]

We had to write off a crop of winter oats sown after spring barley and avadex after a relatively dry summer.
It took a while to work out what was going on but you could clearly see the overlaps from the avadex applicator.
That was cultivated with a big dump of rain week or so after drilling.

 

[Brisel]

We had to write off a crop of winter oats sown after spring barley and avadex after a relatively dry summer.
It took a while to work out what was going on but you could clearly see the overlaps from the avadex applicator.
That was cultivated with a big dump of rain week or so after drilling.

What cultivation did you do before drilling the oats?

 

[Bogweevil]

Perhaps I will use some of the area as a test patch, and perhaps even scratch a bit to see if any grass weeds come up. To be fair it is very active on oats, the area we used it on last year which was the first time we had ever used it had plenty of BG which germinated in late Feb/ march but not one wild oat despite it being in spring oats the year before

You could do a pot test, taking samples of soil, drying them a bit, and then filling flower pots and then sowing pots with some grass seed, then watering. Have a control of pots of soil from your garden (I assume you don't use avadex in the garden). Keep the pots in warm bright place. If the grass does not grow or grows very poorly compared to garden soil ones you may wish to consider other options.

I note the avadex label advises a year gap between application and sowing grass.

For high value crops up to 100kg/ha of activated charcoal can prevent herbicide residue damage from the low levels remaining from herbicides applied the previous season, but probably not worthwhile in low value grass. In countries where crop residues are burnt the dusting of carbon from the burning straw is sufficient to attenuate avadex apparently.

In theory larger seeds, of cereals say (except oats) , could be drilled below the avadex layer with your DD drill - I am afraid I have no experience of attempting this.

 

[robs1]

You could do a pot test, taking samples of soil, drying them a bit, and then filling flower pots and then sowing pots with some grass seed, then watering. Have a control of pots of soil from your garden (I assume you don't use avadex in the garden). Keep the pots in warm bright place. If the grass does not grow or grows very poorly compared to garden soil ones you may wish to consider other options.

I note the avadex label advises a year gap between application and sowing grass.

For high value crops up to 100kg/ha of activated charcoal can prevent herbicide residue damage from the low levels remaining from herbicides applied the previous season, but probably not worthwhile in low value grass. In countries where crop residues are burnt the dusting of carbon from the burning straw is sufficient to attenuate avadex apparently.

In theory larger seeds, of cereals say (except oats) , could be drilled below the avadex layer with your DD drill - I am afraid I have no experience of attempting this.

That's a very good idea will definitely try that, just need to find a snorkel after today's rain

 

[yellow belly]

Not had much problem after Avadex aplied April even in dry years

the amount of rain and warm temperatures since last autumn most Avadex activity will be gone
planted oat autumn cover after spring barley which had Avadex in April

 

[Flat 10]

I have had to spray spring germinating wild oats after autumn Avadex. Perhaps I was unlucky.

 

[DrWazzock]

Any idea if Belkar and Astrokerb applied 26-12-23 will preclude drilling of spring barley? We’d probably plough it down and it’s had lots of rain. My agronomist says it’s not worth risking it. But it’s now a failed crop of OSR due to cabbage stem weevil and looks a hell of a mess.
I’ve plenty of home saved spring barley. The biggest risk is if it doesn’t grow after ploughing then the sand will blow. If it’s direct drilled won’t dilute the residuals? Some of it is absolutely covered in fuzzy cheek plant (blue flowering plant with leaves that look furry but stick spines in your hand) and of course cranesbill which buckled a bit under the spray but has come back stronger.