As soils warm, growers will soon be drilling the 2025 forage maize crop. With good weed control key to bumper yields, Certis Belchim’s technical account manager David Peach outlines three steps to getting it just right this season

Step 1 – Identify targets and take action early

The six weeks post crop emergence are critical to forage maize crop performance, as plants are so sensitive to competition from weeds for water and nutrients.

If left unchecked during this period, yield losses can reach 50%.

This makes a pre-emergence herbicide important, as it holds weeds back and limits the impact of any delay in post-emergence spraying.

It also sensitises target weeds and improves efficacy of follow up sprays.

The most damaging species include polygonums such as knotgrass, black nightshade, mayweed, orache and fat-hen. Blackgrass and annual meadow grass are also problematic in some regions.

It’s important to know which species are present, as this can have a bearing on which herbicides you choose once the crop is in the ground.

Plenty of growers are planting on their own land, so will have an idea about field history, but there is still a lot of maize grown by contractors on rented land.

This presents its own challenge in knowing what species are there and, in such situations, the case for a pre-emergence spray is strengthened.

A holding spray can buy you a bit of time early on, so you can see what is left behind, then you can deal with what’s there before any difficult weeds get away.

Step 2 – Design your herbicide programme

Either straight pendimethalin or Wing-P (pendimethalin + dimethenamid P) pre-emergence are solid, broad-spectrum foundations to a maize weed control programme.

Following your pre-emergence spray, it’s then crucial to be walking the crop regularly and see what weeds come through.

You are inevitably going to have some broad-leaved weeds and, in some situations, growers will need a herbicide mix with activity on grassweeds.

A three-way mix of Osorno (mesotrione), Fornet 6 OD (nicosulfuron) and Diva (pyridate) covers all bases, with the three actives complimenting each other well.

Mesotrione boosts residual control, nicosulfuron is effective on grassweeds and a range of broad-leaved weeds, and Diva offers broad-spectrum contact activity.

In Certis Belchim trials, pyridate in a three-way mix always improves control of a wide range of competitive weeds, compared to mesotrione and nicosulfuron alone, particularly cranesbill, mayweed, and fat hen.

The company’s work has also shown that pyridate is a safer addition to the tank than dicamba, which when applied in hot conditions can check the crop significantly.

Finally, apply herbicide mixtures when weeds are small to get the best control. In most scenarios, you only get one post-emergence hit, so don’t ask too much of the chemistry.

Step 3 – Adapt to the season

Since February, it’s been very dry across the UK.

Bear in mind that pendimethalin is relatively insoluble, so if you are faced with low soil moisture, it might be worth delaying your first spray.

Growers have the option of going early post-emergence, adding a contact herbicide like Diva to a residual like pendimethalin to take out any emerged weeds. This mix needs to be applied from the two true leaf stage of the crop.

If taking this approach, it is best to follow with an Osorno + Fornet 6 OD + Diva mix where you have broad-leaved weeds and grassweeds, or just Osorno + Diva where broad-leaved weeds are the only target.

When using any mesotrione product like Osorno, make sure you are aware of the following crop restrictions in both autumn and spring after the season of application. More information can be found on the product label.