quick CSFB question

[Neddy flanders]

Neonics seed dressings would have reduced the adults feeding on the emerging cotyledons, correct?

would they have stopped the laying of eggs in say Oct/Nov that has led to the spring damage this year?

 

[Shutesy]

I doubt stopped, possibly reduced due to there being fewer adults about. I think before neonics were banned they were keeping CSFB at very low almost unnoticeable levels, now the population has exploded with nothing much to hold it back across the country. I think if neonics were re-instated to as they were before I doubt they would have bugger all effect on CSFB numbers now!

 

[yellow belly]

the biggest benefit that neonics have is that we do not spray pyrethroid that kills all other inscects that come into contack with it

neonic seed dressing only affected the inscects that eat the rape seedlings

reintroduction of a seed treatment would take time to reduce numbers as csfb that now come into the rape fields july onwards laying eggs all the time

it is also compicated not all csfb pupate in the first autumn

in past years before nionics seeing a lot of adults at harvest did not always produce a lot of adults in September

imho one of the biggest problems is that most farmers either cultivate or spray out their rape volunteers before early September

 

[Neddy flanders]

the biggest benefit that neonics have is that we do not spray pyrethroid that kills all other inscects that come into contack with it

neonic seed dressing only affected the inscects that eat the rape seedlings

reintroduction of a seed treatment would take time to reduce numbers as csfb that now come into the rape fields july onwards laying eggs all the time

it is also compicated not all csfb pupate in the first autumn

in past years before nionics seeing a lot of adults at harvest did not always produce a lot of adults in September

imho one of the biggest problems is that most farmers either cultivate or spray out their rape volunteers before early September

but fields of rape volunteers don't seem to be eaten by CSFB. plant 40 seeds/ m2 in wheat stubble and you end up with nothing.
My point is, if dressing was re-introduced tomorrow would it prevent spring CSFB damage. surely someone planted a trial this year with some treated seed?

 

[Brisel]

Neonics seed dressings would have reduced the adults feeding on the emerging cotyledons, correct?

would they have stopped the laying of eggs in say Oct/Nov that has led to the spring damage this year?

Yes.
Yes, at a reduced level. Less beetles left to do so & the stem feeding ought to result in a few more being killed though I don't know how effective the seed dressing is by then. Enough to disorientate a bee might not be enough to kill a larva in the plant stem

As ever, it's rarely that simple. A few years ago a colleague of mine running a farm in Herts managed to get some seed treated under the NFU's emergency dispensation available at the time. It only lasted 24 hours longer than the untreated crops - one mouthful might have been enough to administer a lethal dose but the numbers of CSFB were so high that they overwhelmed the plants anyway. That's an extreme example & he had a few years of not growing osr but is now doing so again successfully.

There's a piece in the latest Arable Farming magazine on not controlling volunteers in stubbles from the previous crop to keep them entertained. The trials work was far from conclusive but some effect was seen - treat you old stubble volunteers as a trap crop & they won't need to migrate to a freshly sown one. Their wings degrade once they have been settled in a field for a while.