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Then & now, from mini ice age to grass in December

Date Added: 23/12/2015

By Richard Elsdon, Technical Consultant, United Oilseeds

 There is no consensus amongst historians as to when, or even for how long, the mini ice age lasted in the Northern hemisphere. There seems to be a general, if begrudged, agreement that it extended from roughly 1350 to the middle of the nineteen century with some warmer spells mixed in. Most of us are probably aware that such extreme cold made winter fairs on the frozen river Thames possible, as well as ice skating competitions on some frozen rivers and canals.

 What I did not realise was that the celebrated violin maker, Antonio Stradivari, produced his famous musical instruments during this period. Colder weather helps wood to grow more dense and the excellent quality of the sound his instruments produce is as a result of the denser wood that was available to make them.  This same period also saw the introduction of buttonholes and buttons, as well as knitted underclothes, in order to keep human bodies warm by holding clothing together and excluding draughts.

 It is almost impossible to imagine cold weather like this after we have enjoyed such a mild autumn and early winter. Autumn planted crops have grown well with some oilseed rape verging on having grown too well. Even at home, in spite of having mown my lawn in early December, it looks as if I had not bothered and is still growing.

 This surge of autumn growth indicates that the soil temperatures are still above the seasonal norm. In the South West, temperatures are between 10 and 11 C and even in the slightly colder east of the country they struggle to dip much lower than 9 C. These temperatures are important as many growers will be using Kerb, or other formulations of propyzamide, and it is important that the chemical is not applied until the soil is below 10C, and cooling. If it is applied too soon, it may break down too quickly to control the black grass and it is too expensive to waste!

 Chemical runoff is another issue is another issue that farmers should address. Over the last few years, the water companies have been telling us all that allowing chemicals to make their way into water courses is not acceptable and various codes of practice and voluntary initiatives have been published. If we do not abide by these codes and initiatives, we may well find that either approved application rates drop or the chemical is withdrawn from permitted use. The first option would be very damaging, the second disastrous!

 Where propyzamide or carbetamide is to be applied we need to ensure that the soil is not so wet that some will run off.  A wet leaf is not a problem, provided Astrokerb (propyzamide plus aminopyralid) is used at the appropriate time, when the leaves are dry for at least an hour, to allow the aminopyralid to bind to the weed leaves.

 On those fields where the black grass is either particularly severe or large you may want to use a tank mix of propyzamide plus either laser (cycloxydim) or Falcon (propaquizafop). This unlikely tank mix does work remarkably well and will give better control.

 Before leaving the subject of late autumn spray application, do please check the rape crop for disease and where necessary consider a further addition to the tank and that is an appropriate fungicide with (after consulting your agronomist) some synthetic pyrethroid to control the larvae of the cabbage stem flea beetle.

 While I do not want to see the return of a mini ice age, I think some seasonally cooler weather would be useful. Not just to control the black grass - but also the height of the grass on my lawn!

Merry Christmas and Happy New Year to All!

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