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May – Weed Control Options In Maize by Sam Pociecha

Weed Control options in Maize 2023

Traditionally forage maize has been favoured by livestock farmers for its ability to produce quality, high-yielding forage often whilst utilising farmyard manures. Increasingly maize is being grown for use as a feed stock for use in anaerobic digesters as well as for combining as grain maize.

Whilst the popularity of maize grows, it is not without its challenges and there are areas which we need to be mindful of when thinking about the agronomy of the crop to ensure the best outcomes.

Weed control is fundamentally important, maize does not like competition from weeds and early removal of competing plants is key to a successful crop.

Knowing what weed pressures may occur from the start is important, if drilling early (April) or in a field with a known high weed bank then a pre-emergence herbicide based on pendimethalin should be a pre-requisite. Like their use in cereals pre-emergence herbicides will always work best when applied before the emergence of the crop and weed. Good seedbeds free of clods and soil moisture are important however in a dry period you will generally always see the benefit of a pre-emergence herbicide where you know you have a high weed burden. The pre-emergence herbicide will suppress weed growth enough to allow crops time to establish and give more leeway for the post-emergence herbicides application, which can be a big advantage if contractor applied, and time is at a premium.

Following the removal of Calaris post-emergence herbicides in maize generally now rely on the three key actives:

  • Nicosulfuron – (Fornet, Milagro 240 OD) primarily for grass weed control and some broadleaved weeds.
  • Mesotrione – (Callisto, Barracuda) primarily for broadleaved weeds with some residual activity.
  • Pyridate – (Diva) strengthens activity on weeds like cranesbill or where applications have been delayed and a faster knock down is required.

Other actives also include foramsulfuron + iodosulfuron-sodium (MaisTer WG) which has a very broad weed spectrum against both grass and broadleaved weeds. Prosulfuron (Peak) useful where for problematic polygonums. Fluroxypyr (Starane, Hurler) can help where field bindweed is an issue. As well as Clopyralid (Shield Pro) & Clopyralid containing mixtures (Leystar) can be useful. Adhering to growth stages and total dose rates is important to avoid damaging the crop.

Whatever active or mixture is used, the most important aspect of post-emergence weed control in maize is the importance of not leaving it too late. Working with your BASIS qualified advisor will ensure you are using the best actives/product combinations for the situation to get the best outcome for your crop ensuring maize crops look like the crop on left and not the right.