The area of maize in the UK is expected to rise again this year and early weed control is essential to get the crop off to a good start. Last year in some parts of the UK dry conditions at planting meant that pre-emergence herbicides such as pendimethalin did not work so well and troublesome weeds such as mayweeds and seedling thistles came through and needed cleaning up. In some areas the situation may be similar this year. The choice of post-emergence herbicides is also limited.Dow Shield 400 has a full label recommendation for use in forage maize post-emergence after the three leaf unfolded stage (GS13) and up to the 9 leaf unfolded stage of the maize crop. It is applied at a dose rate of 0.25 l/ha in 200 to 250 litres of water. The maximum total dose is 0.25 l/ha so it is important to apply the treatment before annual weeds get too big.“If you are looking to control mayweeds and seedling thistles, don’t let them get beyond 4 true leaves,” reminds Alex Nichols of Dow AgroSciences.“Dow Shield has upgraded both its formulation and packaging, so it is much easier to use. The more concentrated formulation has the same weed control efficacy, the same crop selectivity and the same excellent compatibilities, but it is applied at half the old dose rate. The Dow Shield 400 pack has been improved substantially. Now it is made from material that is 50% lighter than before and is transparent so you can see the contents easily. Nevertheless it is very strong and, as it has smooth inner surfaces, it is easier to rinse out. It has self-seal cap technology and no foil seal. The bottle and cap are made from the same material so they can be disposed of in the same way, making the whole spraying process more efficient and pack disposal easier and quicker. The outer cartons are made from 85% recycled cardboard,” says Alex.Dow Shield 400 is an effective herbicide for the control of difficult perennial and annual weeds. It controls creeping thistles, volunteer potatoes and a range of annual broad-leaved weeds including corn marigold, groundsel, mayweeds and smooth sow-thistle. It has label recommendations for a wide range of crops including sugar beet, oilseed rape, grassland, wheat, barley, linseed and forage maize and many EAMUs.