The fight against black-grass continues unabated with astonishing levels of infection across much of the country.
Experts recommend that the key to reducing these massive black-grass populations for next year is to drastically reduce the number of seeds that are returned to the soil.
Incorporating cultural control is critical within the success of any of these approaches to reduce the pressure on herbicides, and one agronomist has decided to take this approach further and is trialling an innovative method of control – weed wiping.
Mark Spicer, part of the Hutchinsons Group, has been trialling a range of experimental approaches for a number of years looking at alternative methods for tackling increasingly difficult to control weeds mainly black-grass numbers, but also rye-grass and wild oats.
"We have reached crisis point in controlling black-grass; chemical solutions are under increasing pressure from resistance and any cultural method of control that can reduce black-grass numbers and thereby the pressure on herbicides has to be a positive, and warrants further investigation."
"We know that if we have 100 blackgrass plants/m² that equates to a seed return of approx. 1.5t/ha, so any reduction in this seed return has to be of benefit – particularly one that does not require a substantial financial outlay.
Weed wiping
Mr Spicer started looking at the prospect of weed wiping a few years ago, after researching the concept on the internet.
"I knew that American farmers were practising weed wiping which is exactly what the name implies, wiping weeds with herbicide from a boom on the back of a sprayer.
"So I spent some time looking at how this would work here on some of the more difficult to control weeds, black-grass, oats and rye-grass and this has led to a collaboration with Boston Crop Sprayers. (BCS)
"A weed wiper is a kit basically attached to the back of the boom which is made up of a row of sponges that are gravity fed with the herbicide.
"The kit is currently manufactured by an American company, Schnuker, and is not yet available in the UK, but as the only agency in England, we are hoping that the first unit will be arriving very soon which will allow us to experiment with it fully," says David Hildred, managing director of BCS.
"We were interested in the concept, not just from a cereals weed control concept, but we think it would be interesting to try weed wiping in a range of crops such as brassicas and sugar beet.
"A farmer in Bedfordshire had a weep wiper retrofitted to his conventional sprayer to apply glyphosate at a concentrated rate to destroy wild oat and black grass seeds ahead of the next crop.
"There is no doubt that we have been able to kill off a large amount of the black-grass and prevent a huge seed bank being returned to the soil.
"We need to do some further work to quantify this, but the reduction is significant enough to warrant spending more time on the concept," says Mr Spicer.
"What we have found is that timing and speed of application of the glyphosate to the weed is critical; the black-grass has to be in flower and not yet filled, and the weed really needs to be wetted so a higher speed works better.
"There needs to be a gap between the weed and the crop - to ensure that the herbicide is not wiping the crop at the same time as the weed, so a good PGR programme should be used when considering weed wiping.
"This is only the second year of trialling the approach, so no doubt we still have much to learn about optimising the efficacy and also defining what levels of control we are able to get, but work that we have planned over the next year with the co-operation of the technical team at Hutchinsons should put us in a better position to have a clearer picture."
