North: Cabbage stem root fly invades oilseed rape crops

Rain at last. After a mere 6mm rain in September, we’re back on track with our first proper dose in a full month. The dust bowl of Lancashire can now revert to normal.

Sowing is 80% complete, barring crops after maize and potatoes. Of course, its probably rather early, but what can you do in such outstanding conditions. A major change in policy has been to reach for the pre-emergence herbicide can – we’re not bothered about blackgrass in Cheshire and Lancashire, so post-emergence spray has always been good enough. But after last year’s brome problems, early sowing and rapid emergence have prompted the need for a much more serious approach this time.

About 90% of September sowings have been treated pre-emergence and these will all get a follow-up before the end of this month. Expense is certainly an issue, but more important is adequate grassweed control. So two moderately priced half-doses will be required to achieve satisfactory control. Throw in some aphid control and worry about what’s left in the spring.

Oilseed rape is mostly looking great – apart from a couple of exceptions where cloddy soils baked out and partially emerged crops headed south again.  Most crops already have six leaves and some are 30cm tall – ridiculous. Flea beetle has been bad, but cabbage root fly far worse (pictured). I don’t really wish to confess the number of foliar insecticide doses to date. Success has been good so far, but we’re waiting to see if a late-emerging generation of root fly now invades, which is quite possible. We’re on standby for a final insecticide treatment before closing the gate for winter.


So the challenge is now on. How do we take costs out and still maintain yields in order to squeeze a margin out of crops in the current market conditions?  There’s going to have to be a serious re-alignment in growing costs next spring.

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