November 16, 2020
Talking Agronomy – Jo Bell – Winter 2020
This season is certainly justifying our decision to stick with OSR, albeit on wider rotations than in the past. We have only lost two very small fields so far despite almost no pyrethroid spraying.
What’s more, coming into mid-October, crops are showing relatively little flea beetle damage, giving us hope that larval levels will also be low next spring. Direct drilling into longer stubbles with buckwheat companions and seedbed fertilisation has really helped; especially with this season’s lower apparent pest pressure.
Crops after spring barley are encouragingly clean too – even after the rain that has brought on such a delayed flush of black-grass in what is definitely a high dormancy year. Not having had to use much clethodim so far has been helpful for crop safety and spraying flexibility.
Stretching the OSR rotations and varietal choice has helped keep phoma levels low. Where we have reduced disease pressure the new phosphite-base bio stimulant, Curative is likely to be our first autumn treatment, given the promise it has shown in early Agrii trials.
The extra disease resilience it appears to give by boosting the enzymes involved in cell wall thickening could be just what we need to support prothioconazole as tebuconazole comes under increasing threat
Employing the biological early where disease levels are lower may even give us the flexibility to combine our prothioconazole with the propyzamide we never want to apply until conditions get cold enough. Compared to prothioconazole , Curative looks like having more tank mix flexibility with any earlier residual graminicide that may be needed to hold black-grass back in the interim where clethodim hasn’t been used. Where any PGR is needed metconazole will be deployed.
Weed control in the winter linseed, being tried by some as an alternative to OSR, is proving much more of a headache. Spring barley volunteers have really been competing with the crop and black-grass is now coming through strongly. In waiting for the linseed to be big enough to tolerate clethodim, we are having to tread a very fine line between efficacy and crop safety.
This is a line we’re also treading carefully with any winter barleys that didn’t get a pre-em when the weather turned. They went into decent seedbeds, so peri-ems will do fine. But we are having to get the rates spot-on. And, of course, with such a high dormancy black-grass season, pick products that give us the best possible residuality and use the Backrow to hold them in place as firmly as possible.
With grassweed control – ryegrass and bromes as well as black-grass– our Number One winter cereal priority, we are heartily glad we have yet to start sowing our wheat. A week ago, we were seeing little, if any, black-grass in the stubbles. But now it is coming through everywhere. It may have to be pre-Christmas glyphosate for some early sown crops, I’m very much afraid.
We shall be going-in with our glyphosate, then drilling without delay just as soon as we get a window now, starting with the least problematic fields and leaving the worst until last. Wherever possible, we won’t be doing so without a decent chance of getting a pre-em on within 48 hours. However, we have enough flexibility to step-up our peri-ems if the weather gets in the way.
The sheer speed of black-grass emergence means we will be including an approved glyphosate with the pre-em wherever we have a gap of more than a few days between spraying-off and drilling. We will then be boosting our pre-ems with timely peri-ems as the crops emerge. And should pre-ems prove impossible, peri-ems will be followed by decent post-ems along with the first of what may well have to be two BYDV sprays on all but the latest sown crops, timed carefully with the Rhiza Contour Tsum model to target the damaging second generation aphids.