Understanding your soil to optimise weed control

Choosing the right herbicide is often seen as the starting point in weed control, but we should go back a couple of steps to establish a baseline.

To optimise weed control in all spring cereal crops, it is essential to understand the impact of soil type, previous cropping history and problem weeds that may have been present in the area before.

For example, many weed species are persistent germinators and their pattern of germination can be all year round. Think of groundsel and mouse-ear chickweed; they germinate and grow when everything else is static.

Soil type

Different weeds prefer different soil types, looking at the high organic matter, low pH soils over to the mineral soils with suitable pH.

In perfect conditions between 80-90% of weeds emerge in the first flush. Moreover, depending on the weed species and a range of environmental and soil conditions, the remaining 10-20% emerge throughout the season.

Perfect conditions are challenging to achieve in practice. So, a judgement has to be made by the agronomist, knowing the field history and understanding the interactions between soil types and weed growth and, of course, the weeds present on the day the fields are assessed.

The programme of weed control is based on collating the information, identifying the key weeds that cause the greatest yield loss and select the product or products that best match the weeds scenario present.

Weed size is a key element to achieving good control. Most manufacturers want to target small to medium weeds (as per their product label recommendations). However, this is often not practical, most commonly because of unsuitable weather.

The agri-chemical giant that is FMC, has purchased the former DuPont broad-spectrum range of cereal herbicides, with popular brands such as Ally MAX, Cameo MAX and Harmony MAX. These brands are readily available in all agri outlets and form the backbone of excellent weed control.

In nearly all instances these brands are tank mixed with an additional product to further broaden the weed spectrum, but also to reduce weed-resistance pressure.

The latest product on the market is Kinvara. When put together with the chosen FMC herbicides, the tank mix programme provides full control of all the economically essential weeds present in most spring crops.

We sometimes take for granted the control of groundel and brassica weed species, since the control afforded by the FMC range has managed these weeds almost as incidentals. One only realises the levels of their background and in most cases endemic weeds when FMC branded products are not used.

In summary, know your field and cropping history and the potential impact it has on weed species present.

Identify the economically most important weeds, select the optimum weed control “foundation” product – be it a Cameo MAX / Harmony MAX – and select the additional broad-spectrum product, Kinvara, to maximise results.