South: Prioritise early winter spraying

Now we have had some decent rain – a good 1-2 inches last week – blackgrass control has become our top wheat management priority. This is especially so after a highly variable pre-em performance following such a dry drilling season with questionable seed-bed quality in some cases.

The combination of much needed moisture and the balmy October means blackgrass is coming through and growing away strongly, so we are making sure to target it at 1-3 leaves with full rate Hatra (mesosulfuron-methyl + iodosulfuron-methyl-sodium). Having used flufenacet as the base for our pre-ems, we are combining it with a pendimethalin-based residual for the greatest all-round activity.

Even if the blackgrass gets beyond three leaves we will keep on spraying to take full advantage of this season’s very active early weed growth and whatever spray days are available. Our blackgrass trials research centre at Stow Longa, near Huntingdon confirms November invariably gives the best control with Atlantis (iodosulfuron + mesosulfuron) chemistry – 93% against 88% in December and less than 60% in April.

As well as hitting the blackgrass hard, our November spray should deal nicely with any volunteer rape, annual meadow grass and broad-leaved weeds that may have escaped compromised pre-em activity.

With plenty of aphids still around, we are including a follow-up aphicide in the mix for early-drilled wheats, while all second wheats are getting Nutri-Phite PGA as a matter of course for its timely rooting boost.

Some crops of Solstice and Oakley, in particular, were quite stressed by high levels of mildew before last week’s rain. Although not sufficient to bother treating, we have been making sure to give them enough time to recover after their moistening before going in with a robust post-em spray.

Coverage is everything to give us the optimum weed control we need from the treatment, which means spraying dry leaves wherever possible at a forward speed of no more than 10-12 km/h with a low boom height, a good 3 bar of pressure and flat fan nozzles.

Almost ideal oilseed rape sowing conditions have meant some of the biggest and best stands of rape we’ve ever seen across our patch. The dry weather did not get in the way of early crop development, though thankfully it did restrict phoma levels.

This is allowing us to focus most of our first fungicide sprays on metconazole with its valuable early growth regulating but disease protectant rather than curative action – essential in view of the far better winter survival recorded in last year’s Brotherton SMART Farm trials from 32cm tall treated crops compared to untreated ones at fully 60 cm.

We do have a very few, smaller, less well established oilseed rape crops. They are carrying relatively more phoma, so flusilazole is obviously our active of choice here.

Once we have completed these initial sprays we will be keeping a careful eye on disease development so we can target the second fungicide as effectively as possible – either before Christmas or, for the most part, in January. And with light leaf spot becoming increasingly problematic this will be as much of a priority as phoma in most cases.

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