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Micro-granule applicators have been back in action this autumn but correct settings are essential for effective use of Avadex to help tackle problem grassweeds. Peter Hill reports
Specialist applicators and boom fertiliser spreaders capable of handling microgranules have been busy this autumn as growers broaden their approach to grassweed control.
Applying Avadex Excel 15G - a once-popular herbicide enjoying a major comeback - has become a key component of control programmes once more now that foliar weed killers have become less effective, in particular against blackgrass.
With a mode of action different from almost all other autumnapplied herbicides, the granular material can play a useful role in lifting the overall performance of a herbicide programme, particularly in winter barley, where there are few active ingredient options.
Application accuracy is essential, though: the recommended rate of 15kg/ha equates to just two granules/sq cm. Even distribution is therefore crucial.
Jim Hammond of SCS Spreader & Sprayer Testing has tested a lot of applicators - partly because they have to be checked under the NSTS scheme, and partly because growers recognise the need for distribution accuracy.
"I would estimate there is probably an even split between machines that are pretty much spot on and those that need adjusting to get things just right," he says.
"Even distribution is important for cost-effective use of fertilisers. but with Avadex granules it is crucial because of die small amount of material going on."
The required NSTS test (costing £180) is limited to checking that the applicator delivers the correct rate of herbicide, plus or minus 10%, but not the distribution pattern.
For an extra £50 a dynamic test can be...