Cabbage Root fly

[Chalky]

After all the issues of establishing a rape crop, we have some real crackers this year. However, the best of the lot will probably lose 20-30% of its stand through this pest. Drilled 18th August(early for us- that is the cause)- and has obviously been attacked towards the end of August. With the earlier drilling season, is anyone else seeing any damage? White grubs 2-3mm long chewing the tap-root about 15mm below the surface. See leaves going limp & when pulled, the stem breaks where chewed & rotten. We are Humberside in a non veg area.

usually a few days sowing difference negates all damage, as OSR sowing dates are at the latter end of the CRF laying period.

 

[Minesapint]

Walked some rape this evening, and a fair few plants affected on the headland. Drilled 25th August so not that early. Was deciding whether to get the Centurion on tomorrow, but it is so stressed by the dry I think better left alone. Will walk the remainder tomorrow to see how much is affected by root fly, some fields are thin enough already after serious flea beetle issues. Always seems more of a problem on our gravel.

 

[Brisel]

@Chalky what county are you from?

Neonicotinoid seed dressings weren't supposed to be that good on CRF but my Lessons on the pest said that brassicas sow before mid August were most at risk. I've not seen the pest myself - I'm more worried about turnip sawfly down here.

 

[cricketandcrops]

Doubt neonics would control - used chlorpyrifos on veg modules to prevent pest as bad attacks would wipe crops out

 

[david]

Didn't the German version of Modesto carry a recommendation for control of Cabbage Root Fly ?

 

[yellow belly]

Had some in the 1980s on mid August planted rape

20 august is the earliest I would plant here at 400 ft in South lincs
If I was further south and lower altitude would wait a day or two longer

 

[DrWazzock]

We drilled on 23 rd August and I have found maybe 2% of plants killed by cabbage root fly so far. Usually two or three maggots at the bottom of each plant.

It's a bad year for flies all round with the sheep having struggled to keep the maggots off all summer.

We need some colder weather.