South: Making the most of spray days

Spray days is what we really need as we come to perhaps the most critical period in our spring crop protection and canopy management programme. Judging from current conditions, we’re going to have to seize every spraying opportunity we can while doing everything possible to maximise the rainfastness of our mixes.

In wheat our crop protection focus has shifted dramatically from the rust that was our chief concern at T0 to the perennial problem of septoria. With very lush crops going into the winter and not enough cold weather for significant leaf loss, we’ve been particularly conscious of the threat and this is why we included chlorothalonil alongside our robust initial triazole spray.

This and lower than normal temperatures have kept the lid on things. But the hugely welcome recent rain  puts us on red alert. Especially as our T0s begin to run out of steam and a more traditional April heightens the risk of spraying delays.

To counter this threat, we’re upping the curative content of our T1 sprays with higher rates of prothioconazole, in particular, while pulling back on protectant levels. This will also help on susceptible varieties with extra eyespot activity. Despite eliminating all active rust (even on Oakley) with our T0, we’re including pyraclostrobin on yellow rust susceptible varieties.

The real possibility of T1 spray delays makes us very glad we employed a split PGR programme on all our wheats this year. Even if we can’t get the balance of our chlormequat plus Moddus on at exactly the right time, the Adjust and Meteor we used at T0 will do much to counter the major nitrogen kick we’re seeing from our best rainfall of the year.

With more severe BYDV than I’ve known since 1989, we’re also grateful we backed-up Deter seed treatment with a full rate aphicide spray in late October in most cases. Even so, we’ve had a few crops which seem to have been infected into January. With milder winters on the cards, it may well be time for a serious re-think of established BYDV strategies.

In oilseed rape, sclerotinia is our key focus. Although sclerotia germination was early this season, low temperatures have generally held back spore release. Again, wet and warmer weather changes all this, and we are now seeing  significant petal stick as the early flowers fall.

Our very late stem extension metconazole has given us a really good base for sclerotinia control as well as holding back the main raceme and promote branching rather than just shortening the crops.

We’re building on this with a robust boscalid spray. The four weeks of protection it gives means we may not need a second spray for all but our early crops.  If flowering continues to be extended by the colder than normal April we’ll certainly be topping up where necessary. Always supposing we get the spray days, of course.

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