Stop chickweed smothering new sown leys this autumn

UK - August 03, 2011

Chickweed can quickly smother young seedling grass in autumn sown leys and should be sprayed to maximise the returns from investing in a new re-seed.

“It is almost inevitable that common chickweed will germinate alongside grass as both establish easily in the warm, moist soils at this time of year,” explains David Roberts, grassland technical specialist for Dow AgroSciences.

“But chickweed will soon out-compete the spindly young grass as it has much bigger leaves and grows more vigorously.  Left too long, it will kill the grass leaving large gaps in the sward.  I have seen new leys where chickweed has covered 50% of the field.”

Chickweed is the most common annual weed in the UK.  It seeds continually from spring to autumn, with each plant capable of producing 15,000 seeds.  When the population of mature chickweed reaches ten plants/m2, the amount of ryegrass left can be as low as 50% - dramatically reducing productivity.

Mr Roberts advises farmers to spray with a herbicide such as Doxstar at 1.5 litres/ha in 200 litres of water/ha, once the number of chickweed seedling reaches 5-10/m².  For best effect, the chickweed should have at least two true leaves and be up to 50mm in diameter when treated.

“Translocated products like Doxstar are particularly useful for spraying new sown leys as they do not adversely affect grass growth, unlike herbicides based on older chemistry such as MCPA and 2,4-DB,” says Mr Roberts.  “The sward can be sprayed once the grass has three true leaves.

“An added advantage of using Doxstar is that any seedling docks that have germinated from seeds brought to the surface by ploughing and cultivations, will also be knocked out before they can gain a foothold.”