In numerous counties, the effects of the long, hot summer and the onslaught of cabbage stem flea beetle (CSFB) on oilseed rape crops are still being felt.
Crops that were sown in early-August have established well on the whole and were large enough to withstand the gnawing mouthparts of the adult flea beetle. However, crops sown in mid to late August were emerging just as the largest inward flights of flea beetle were taking place. This was compounded by the effects of the dry conditions, meaning the plants that did emerge were growing slower than expected. In the end, many crops suffered serious damage before finally succumbing.
On crops that have survived this torrid period, we can see where the female cabbage stem flea beetles were able to lay eggs on the young leaves. Their larvae have now burrowed into the rape leaf petioles and will sit there quietly all winter, munching away at the plant tissue. As they do this, they will be destroying the green leaf area that was meant to be feeding the plant as it develops its structure.
In many of the situations described, a lot of growers are considering whether or not to abandon the oilseed rape crop and re-sow the fields with beans. While this has the potential to offer a reasonable margin, if you plan to do this then care must be taken if certain herbicides have already been applied to the field. Many of the residual and contact herbicides that we use in oilseed rape for weed control require the field to be left for an extended period of time before a succeeding crop can be sown.
You can read more about the specifics of this below:
Once you have made the decision to sow a crop of winter beans, consideration needs to be given to the weed control programme for that crop. However, before getting started you should ask yourself; Are grass-weeds a problem?
If the answer to this is 'Yes', the use of Kerb Flo (proyzamide) is almost certainly going to be required. This must be applied pre-emergence of the beans and preferably within seven days of drilling being completed. You can then decide on a tank-mix with other required herbicides to help with the control of broad-leaved weeds.
Some products for residual weed control in beans
The bean crop, be it winter or spring, will require the availability all the major/minor nutrients, apart from nitrogen which cannot be applied to these crops under nitrate vulnerable zone (NVZ) rules. An ideal one-pass product for delivering all the required nutrients to pulses is the new polysulphate product, PKPlus, which is formulated as:
Programme to supply P, K and S in one pass to all pulse crops:
For further assistance with arranging your cropping and agronomy requirements, please contact your local Frontier agronomist.