East: Desiccation problems are on the cards

Most combinable crop spraying is almost complete, although some wheats are still receiving T3 treatments to top up foliar disease control.

Some oilseed rape crops this year will cause desiccation problems due to their uneven development and maturity. There will probably have to be some fiddly part-field spraying with glyphosate at different times to accommodate this variation.

An alternative is to apply a pod sealant and then follow up with glyphosate once the more backward areas of the field have reached the appropriate stage for treatment.

The sealant will help protect the more mature areas of the crop from damage when the sprayer travels through it. But this technique will require careful selection of water volumes and nozzles to avoid the pod sealant preventing full uptake of the later-applied glyphosate.

Quality wheats have been sprayed at ears emerged or just into earlyflowering to try to control fusarium species and associated mycotoxins.

As milling wheats reach milky ripe stage they will receive a top-up offoliar urea or a stabilised nitrogen product to boost protein levels.The need for this late addition of nitrogen was a topic of discussionat Cereals with the crop nutrition research scientists.

Their work with NIR looks promising, but not yet ready to be appliedpractically. Nevertheless, given the uncertainty over nitrogen uptakeand loss this year (especially where urea has been used) it would seemtoo risky to drop the late nitrogen treatment on promising millingcrops.

Now is the time to assess the effectiveness of treatments, especially of grassweed herbicides, during the season.

Generally where robust pre-emergence residuals were applied they workedwell allowing surviving grassweeds to be tidied up with Atlantis orPacifica (iodosulfuron + mesosulfuron)in the spring.

Where these products have been used as the only grassweed treatment,due to lack of opportunities to spray in sequence with autumnresiduals, poorer control has sometimes resulted.

The question is whether poor control is down to unsatisfactory application technique and conditions or to herbicide resistance.

Any surviving areas or patches of blackgrass will, therefore, be testedfor resistance using the rapid Petri-dish test developed by Rothamsted.This can produce a result in as little as six weeks allowing grassweedcontrol decisions to be made before establishing the following crop.

Areas or fields where blackgrass control has been poor will need to befocused on to maximise cultural control perhaps even resorting to theplough to bury seed or use the stale seed-bed plus glyphosate approach.

Where Atlantis target-site resistance is identified it will benecessary to consider alternative herbicide strategies using pre-em andearly post-em residuals.

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