A Welcome Chill? - Agrii - Connecting Agri-science with farming

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November 28, 2014

A Welcome Chill?

Aha. There was a distinct chill in the air with two good frosts last week and one night colder than any we had last winter. Wishful thinking as we get to the end of November, I know, but could this be the start of something?

The open autumn has been really valuable for our late-sown wheats, not to mention a number of rape crops that struggled in the dry September. Now, though, we could really do with a nice sharp spell of weather.

Apart from anything else, it would allow us to complete a post-em wheat herbicide programme badly  disrupted by the lack of spray days. Although our pre-ems have generally worked well, we need a decent black-grass follow-up where crops were drilled early, seedbed consolidation was less than ideal or weed seed return was too much for early stale seedbeds limited by the lack of moisture.

Some of our dirtiest wheats are actually behind the plough, underlining that ploughing is far from the magic black-grass bullet some may be assuming. Rotational ploughing certainly has a place. As our Stow Longa research clearly shows, though, it can’t possibly do the job alone where relatively deep tine or disc tillage has spread the weed seed throughout the soil profile. Nor will it be effective unless it’s good enough to consistently bury all the trash to sufficient depth.

A good cold spell would be very welcome for black-grass control in our OSR too. Soil temperatures were low enough for us to make a start on propyzamide applications last week. But only where phoma levels and concerns over future spraying opportunities were particularly pressing. Otherwise, we’re holding-off for some decent frosts to open up some pretty big canopies for the best spray-to-soil contact.

After a slow start, phoma has really taken off over the past three weeks. Resistant varieties are proving a real godsend, giving us just the sort of treatment flexibility we’ve needed with so few spray days to play with. We gave our taller crops an early dose of metconazole the best part of two months ago, so we’re now looking to get round everything with the most economic combination of prothioconazole and tebuconazole for light leaf spot as well as phoma control.

Cold weather would also call a much-needed halt to the substantial aphid reproduction and movement we’ve seen throughout November. With above average Myzus persicae levels we’ve taken no chances with most of our more southerly and westerly OSRs, using the best value non-pyrethroid, flonicamid wherever necessary. All our early cereal drillings had an insecticide follow-up to their seed dressing a good time ago. But the continued mild weather has meant we’re also having to spray later plantings.

Thanks to the more resistant varieties we’re growing, we’ve only found traces of yellow rust in our wheats so far. Some Septoria is evident in early drillings but it’s nowhere near enough to cause us concern yet – always supposing we get a winter this year, that is!

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