Arable
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Robust pre- and post-em programme key for maize success Maize Growers Association agronomist, Jon Myhill, reviews the options available for maize growers hoping to achieve the best weed control in this year’s crop. The most effective way to achieve weed-free maize is via a preand post-emergence herbicide programme. The timing of post-emergence weed control treatments is critical and should be targeted when the first cotyledon weeds show. Once the crop has reached the 4–6 leaf stage, the maize seedlings can usually withstand and out-compete most weeds; however, there is still a need – up to the 6-8 leaf stage of the crop – to clean up competitors such as black-grass, ryegrass, potatoes, thistles and black nightshade, to
minimise potential problems for the following crop. Listed below are the current postemergence options available: • Nicosulfuron e.g. Milagro For use where grass weeds, particularly ryegrass, is a problem. The herbicide does have a very limited range of control for broadleaved weeds. For the common weeds of orache, nightshade and fat hen, some control can be achieved at higher rates of use – however, success will depend on the weather, size of weeds etc • Mesotrione e.g. Callisto
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On its own, this herbicide controls two of the problem weeds – black nightshade and fat hen. Control of orache is relatively weak Nicosulfuron + mesotrione e.g. Elumis This mixture either comes as a ready-made formulated mix or can be made up as a tank mix. This combination does give the widest range of control of broadleaved weeds of any post-emergence product and is the mix of choice to follow a pre-emergence application
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The weakness of the mix is its relatively poor control of orache. The best control is achieved when the weeds are at their smallest Mesotrione + S-metalochlor e.g. Camix A pre-emergence herbicide that can be used as a post-emergence spray if required. Compared to mesotrione alone, it does not bring much to the party in the post-emergence slot Foramsulfuron + iodosulfuron + isoxadifen e.g. MaisTer Whilst the susceptible list for MaisTer is relatively small, and one of the main three, orache, is missing, these chemicals comprise the only herbicide that will have a good effect on blackgrass and, to a lesser extent, cranesbill. Prosulfuron e.g. Peak On some farms, the three main problem weeds (orache, fat hen and black nightshade) are not present, and it is more the polygonums that are a problem. In this case, Peak presents a good alternative – however, Peak is not an option where rimsulfuron, nicosulfuron or foramsulfuron + iIodosulfuron (due to only one
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28 www.farmersguide.co.uk May 2022
28-29 Arable.indd 28
14/04/2022 12:28
