PGRO issues timely pre-em herbicide advice for winter beans

We have reports coming in expressing concern about weed control issues in winter beans, says Jim Scrimshaw, Principal Technical Officer at PGRO. We do have the herbicides to tackle most broadleaved weed problems, but they are expensive compared to lost products containing simazine – and weed control is sometimes disappointing.  The demise of herbicides in all crops is a real issue, and winter beans are not alone in having to look for alternative chemistry.

On a positive note, winter beans offer a good opportunity to tackle troublesome blackgrass populations using Crawler or Kerb. However, those growers planning early drillings and spraying soon after, may not fully benefit from Kerb applications as it works better under cooler conditions more associated with later applications.

Mr. Scrimswaw points out that something to bear in mind with pre-emergence herbicides is that they have a variable but limited time of activity which starts to decrease from the time of application.

Winter beans can be in the ground for a long time before the crop is at an appropriate growth stage for post-emergence bentazone. This expensive material doesnt work well if it is cool and, preferably, its use would be avoided if possible.

For these reasons, he advises that it is worth considering not following the drill too closely with the sprayer – but instead keeping an eye on the drilled seed along with weather forecasts and delaying applications for as long as reasonably possible.

Spraying two weeks after drilling, for example, gives two weeks activity at the other end. While, if the application had been made behind the drill, the herbicide may well have been running out of steam.

Mr. Scrimshaw adds: This approach offers a chance to move the period of weed control, so it is more effective. However, it does require some increased attention to crop and weather conditions, and so is not without risk. PGRO is aware of this as a priority area for research and will be continuing work to seek solutions.

PGRO is the non statutory levy body which promotes and carries out research and development in peas and beans. PGRO growing guides and recommended lists of varieties are the national references for growers. The PGRO publishes ‘The Pulse Magazine’ quarterly, the ‘Pulse Agronomy Guide’ annually, issues bulletins during the growing season, provides education and training courses, and runs grower / agronomist meetings around the UK.