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We need to bridge the gap

Date Added: 19/09/2016

Blog: By Richard Elsdon, Technical Consultant, United Oilseeds

You may have noticed recently that the Chinese have built another exceedingly large bridge which is due to open to traffic at the end of this year. The Beipanjiang bridge, in the south west of China has a deck which is 1854 feet above the river it crosses and will cut down the journey time  from Liupanshui in Guizhou to Xuanwei in neighbouring Yunnan province from around five hours to less than two. The report did not say how much the bridge cost or how long it took to build, but it does look beautifully designed and is a testament to the ability and ambition of Chinese engineers.


Photo: Glabb

I have made no secret of my fascination with these large structures which are there to bridge a gap and improve the lives of the people using them.  Turning nearer to home we have an equally large gap to bridge when comparing commercial yields of oilseed rape with those from AHDB trial results or the very best on farm yields.

Reports vary when it comes to putting a figure on the average yield of oilseed rape from harvest 2016 but most estimates seem to centre around 3 mt/ha. This compares rather unfavourably with AHDB trial results of nearer 5mt per ha and the one or two historical farm reports of yields approaching 7mt/ha.

It would appear that the reason for the poor average yields in 2016 is down to weather, more particularly in June, when the amount of sunlight was down by anything between 30 and 50%.  This is the critical pod filling time for oilseed rape and if it does not have access to enough sunlight it cannot photosynthesize to then produce energy to fill out the developing seed. The result is small seed and less oil per hectare.

So where do we go from here? We know that for a plant to perform well it must be well grown and healthy. The plant pathologists are telling us that light leaf spot (LLS) was particularly bad last year with more inoculum around last autumn followed by a very wet late autumn and early winter which prevented fungicide application. This scenario is likely to be repeated this autumn as already there is a large reservoir of inoculum around and if, as seems likely, we have progressively more rainfall going into the autumn, the disease is going to infect the crop.

Now this is where some possibly tough decisions need to be made. Historically, many growers have timed autumn fungicide application to coincide with the application of propyzamide. On one level this is understandable, as two jobs can be done with one visit with the sprayer.  However, this may not give the best result from the fungicide as the sooner it is applied the more effectively it will both control and protect against the disease.  And, as has been said before, LLS is polycyclic (once infection has occurred the disease continues to cycle).

This is not an easy disease to control but the key seems to be regular crop inspection and early identification. If you think there is a possibility of the disease being present in the field put one or two leaves in a sealed ‘freezer bag’ on your desk and leave it for up to four days to see if the disease develops on the leaves. This is a process that needs to be repeated through the autumn until either the disease is found in the field, or it appears in the bag on your desk.

Once the disease is found talk to your agronomist about the rate of fungicide to be applied as a robust first spray may be needed. This has the added consolation that you will also be helping to control Phoma.

Last year has gone. This is a new opportunity to bridge the yield gap between field and trial results and disease control is a vital part of the fabric of that bridge.

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