East: Saw fly larvae appear in oilseed rape

Three words,  “just in time” sum up the last few days.  The weather is at last favourable and drilling can progress once more.

Oilseed rape crops are mainly past the three leaf stage. There is some evidence of phoma on the early-drilled crops, which will be treated shortly.  Varieties with a rating below 6 will be monitored closely. All crops should be treated when the threshold of 10% infected plants is reached. 

Saw fly larvae have been seen on two oilseed rape crops. Both crops are very forward, but the pest will be closely monitored given the level of damage it can cause in a very short time.Saw fly larva resize.JPGSlug activity is also causing some concern and with restrictions on metaldehyde use, this requires careful management.Blackgrass control at the one to two leaf stage has been achieved using Aramo (tepraloxydim), which has given surprisingly pleasing results in early drilled crops.

The results of my clients’ blackgrass resistance tests have arrived. These will allow me to build individual pre-emergence chemical programmes based on science rather than an educated guess. 

After discussing my results with colleagues it has highlighted considerable differences in resistant populations both between and within farms.  As effective chemical options decrease, attention to detail must increase.

It’s a good time to fine tune wheat seed rates and these should be calculated field by field taking total grain weight, germination, drilling conditions and soil type into consideration. We need to achieve a competitive crop for effective weed control.

Unfortunately, the recent inclement weather means some barley has missed its pre-emergence herbicide. It’s now a priority to get a flufenacet-based product on at full emergence, followed by chlorotoluron if the variety is tolerant.

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