Preparing for the consequences of a mild winter - Agrii - Connecting Agri-science with farming

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February 12, 2014

Preparing for the consequences of a mild winter

Here in Yorkshire there seems to be little, if any, prospect of the good week or two
of winter cold that would have been ideal for our crops, writes Agrii agronomist, Sam Patchett.

One after another, the Atlantic depressions have just rolled in, keeping us virtually frost-free and adding more than enough moisture to raise the possibility of serious early spring fieldwork delays. Unless we see a marked change in the weather soon, it doesn’t look like much of our ground will be fit to travel until well into March and we may be talking about late in the month before we can get on in many cases. With the mild weather continuing to keep many crops, weeds, diseases and insects far from dormant, we’ll have to be right on the money with our early agronomy if we are to effectively protect yields that will be more precious than ever with new crop prices as they are.

Immediately we can travel, one of our first jobs will be to tidy-up competitive weeds like black-grass and ryegrass – especially where the weather got in the way of autumn treatment. Because it has stayed so mild we’ll be adding a pyrethroid in most cases here to keep aphids well in  check. BYDV is a problem we simply cannot afford to have.

As well as the Septoria we can find in just about every crop now, yellow rust infections have become very obvious at a number of our northern trial sites. And not just in the most susceptible varieties either. Even more worrying perhaps is the threat from brown rust in a season that, so far, bears an uncanny resemblance to 2006/7 when the disease proved so devastating.

What really opened the door to the brown rust epidemic in 2007 were growers who didn’t apply a T0 bringing their T1s forward to counter an early Septoria threat then leaving too much time for the disease to cycle ahead of T2. 

If ever there were a year not to do without an early fungicide this would be it. The average 0.35 t/ha response we’ve recorded to a T0 across our extensive trial base over the past 14 years – from a low of 0.16t/ha last season to fully 0.8 t/ha in 2012 – underlines how valuable it is.

To the multi-site activity of Phoenix (folpet) we’ll be adding flutriafol or Brutus (epoxiconazole + metconazole) for varieties that need particular rust protection. The latter is particularly cost effective this season and very rainfast,. Either that or we’ll employ a combination of chlorothalonil and tebuconazole. Where rust isn’t a threat we’ll be going with straight Phoenix. 

With good early plant growth regulation crucial with forward crops, T0 will be the start of our PGR programme wherever possible too, with Adjust our first choice for its activity before conditions warm up enough for ordinary chloromequat. And, where needed, we’ll be taking the opportunity to apply foliar manganese with Nutri-phite PGA to aid rooting.

The mild weather also means we’ll be on high alert for light leaf spot in all our oilseed rape. And, providing we can travel, we certainly won’t be waiting for the start of stem extension before treating any infections we find with Kestrel (prothioconazole + tebuconazole).

Being so well-grown, many of our crops will be needing a dose of Juventus (metconazole) at early stem extension too. The good start this will provide to the sclerotinia programme makes it doubly valuable in a season where cost control is more essential than ever.

Having found molybdenum and boron deficiency in almost every soil test I’ve had done locally over the past four years, these trace elements will be included in our stem extension sprays as a matter of course.

Pollen beetle is another key threat we’ll have to be on our guard against at green bud stage with forward crops in a mild season. I won’t be waiting until the buds are obvious before checking though. Instead, I’ll be opening-up enclosed buds well within the plant as we move through March to make sure we identify any potential problems from the outset.

With the possible exception of barley which I like to avoid starving at all costs, I really can’t see much nitrogen being needed by most of our crops (or able to be applied for that matter!) before mid-March. The mild winter should mean sufficient mineralised soil N to carry them through. And any N we can save for yield rather than the canopy in our OSR by precise fertilisation based on careful N Min and GAI assessments will be especially welcome.