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Earthquakes and oilseed rape

Date Added: 10/03/2017

By Richard Elsdon, Technical Consultant, United Oilseeds

On 4th September 2010, an earthquake measuring 7.1 on the Richter scale hit the Canterbury region of South Island, New Zealand, weakening many buildings but thankfully causing no fatalities. Sadly this was not the case in 2011, when another earthquake caused many buildings to collapse with fatal results. Some claim this  due  in part to the earlier earthquake weakening existing structures.  However, not all authorities agree and point to the second earthquake producing an increased “ground acceleration” that exceeded all previous measurements.

Christchurch in New Zealand is situated near the Alpine fault between the Pacific and Australian tectonic plates.  Damage to buildings took place largely because the energy of the earthquake produced the  ground acceleration, which in turn produced a geological phenomena called soil liquefaction. Essentially, this means that once- stable, compacted land was turned into something resembling blancmange  - causing even the best designed structures to collapse.

Damage to buildings in New Zealand caused by the 2010 earthquake

It is now time to consider the UK arable crop and risks of lodging, specifically oilseed rape. The weather we have been experiencing during the early part of March has encouraged the crop to move in to stem extension mode, with crops increasing in height daily. I have mentioned the importance of managing the crop to achieve the optimum green area index of 3.5 by flowering time in earlier blog  and how this can be done by manipulating the timing and amount of nitrogen. What needs to be considered now, is the possibility of the crop lodging.

Lodging is defined as any stem displacement from the vertical position. The job of the oilseed rape plant is to grow healthy green leaves to harvest sunlight and produce the maximum number of seeds. This situation can best be achieved if all plants stay vertical. Any that lean will shade their neighbour, thus reducing the harvesting of sunlight.

To ensure that your plants stay upright, especially in a thick crop, it may be a good idea to discuss the use of a plant growth regulator (PGR) with your agronomist. This is where decision-making becomes a trade-off between achieving the best standing plant or going for a chemical which will bolster the plant’s resistance to Light Leaf Spot (not that again I hear you say!) and may not quite achieve perfectly vertical stems.

Of the four PGR chemicals that I am aware of metconazole and caryx (a formulation containing mepiquat chloride and metconazole) will achieve a useful PGR effect but little if any effect on LLS. Tebuconazole and Toprex (a formulation of difenoconazole and paclobutrazol) will have a PGR effect and (in England anyway) also have a beneficial effect on LLS reduction. It is at this point that I leave you in the company of your agronomist

As farmers, you endeavour to grow your crops to best advantage, with a careful eye on costs! You can influence the ability of your crop to maintain and upright posture. I strongly suggest you take the measure most appropriate for your crop in your situation.  Resistance to lodging was not something that could be achieved for the buildings in Christchurch.

Richard Elsdon is Chairing this year's joint UOM / AHDB  OSR Seminar at the Holiday Inn at Crick, Northants NN6 7XR, next Wednesday 15 March 2017.  If you would like to attend see more details and free booking instructions

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