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May 14, 2014

South: Unsettled conditions add to disease concerns

More than 100mm of rain in the past two weeks may have dispelled to our earlier concerns over fertiliser uptake but it has seriously limited spray days, reports Hampshire-based agronomist, Iain Richards. It has stretched our T0 to T1 intervals to four weeks in some cases; certainly longer than I’d like in such a high Septoria season.

Thankfully, we didn’t go in too early with the T0s. Even so, we’ve had to rejig T1 mixes to give extra curative activity wherever necessary. This and national SDHI supply problems underline how important it is for us to have a wide range of well-researched options at our disposal.

Despite T1 delays, we’re sticking religiously to our T2 timing plans to make sure we protect the flag leaf as soon as it emerges, even if means an interval of as little as two weeks.

With no real rust problems to speak of so far, like our T1s, our flag leaf sprays will be SDHI-based. There’s plenty of Septoria in the bottom of most crops and the weather promises to stay unsettled, making robust triazole rates essential.

After 2012 highlighted just how alert we need to be to the threat, fusarium infections – foliar as well as ear – will be a key concern alongside Septoria for our T3 sprays if the weather stays damp and we are to make the most of the excellent potential in our wheats.

Most of our spring barleys are looking full of promise too – remarkably, even those that couldn’t be drilled until April for earlier water-logging. Our more forward crops will be getting their T1s imminently. There’s some useful resistance in our varieties these days, But, with rhynchosporium re-emerging in our winter barleys pre-T2 we won’t be taking any chances with our spraying.

The shortage of spray days has also given us real sclerotinia treatment headaches. Our earliest winter OSRs had their mid-flowering spray three weeks ago. And excellent branching in well-structured canopies means there’s no immediate end to flowering in sight. So we’re trying to  get in follow-ups wherever necessary.

It’s a long way to harvest I know, but this season is looking to be an excellent testimonial for hybrid rape. With the just right plant populations and good N and PGR management, the hybrids are looking so much better than pure lines in every respect. DK Excellium is definitely the pick of our bunch. I’ve rarely seen such good branching, so many pods or such depth of podding.

The vigour and speed of autumn development we’ve seen with this sort of hybrid bodes really well for OSR post-neonics. Flea beetle has proved a nightmare on our linseed this spring in the absence of a decent seed treatment, threatening to destroy crops within 2-3 days as they came up. But it’s never been such a threat with winter rape. So I have no doubt that fast developing varieties and more attention to the fine points of establishment will be the keys for the future. Nor, with the excellent canopies we’re achieving, that jacking-up seeding rates must be avoided at all costs.