The Horticultural Trades Association and Zest Sustainable ICM have secured a £50,000 grant from Horticulture Crop Protection UK Ltd to test and evaluate new herbicides for use on container-grown hardy nursery stock.

The trial “Herbicide phytotoxicity testing on a range of container-grown ornamental plant species” will examine six herbicide products, four pre-emergence products, including Emerger (aclonifen), and two with post-emergence activity, over 25 different plant species.

This important research is expected to produce extensive technical knowledge and findings, which the HTA will share with growers, giving them the confidence to further test the herbicides on their own nurseries with their own crop varieties. The aim of this learning is for UK growers to use the new herbicides within nursery weed control programmes in the near future.

Managed by Selchuk Kurtev at Zest Sustainable ICM, the trial is set to start in early spring 2026 at HTA member, Darby Nursery Stock in Norfolk. The HTA will also stage industry open events for spring and autumn 2026, so members and UK growers can see firsthand the impact of the herbicides being tested.

Alastair Hazell from Darby Nursery Stock Ltd, commented:

“We’re looking forward to being involved in the herbicide phytotoxicity trial. Our business has hosted AHDB-funded trials in the past, so we know how important they are in generating practical information which benefits the whole sector.

“There has been a lack of new relevant herbicides for use on container-grown nursery stock over the years, and many herbicides are being revoked on a regular basis, so we hope this trial will highlight new products that provide robust, economic weed control”.

To safeguard the future of UK plant production, the HTA, along with other crop associations, supports Horticulture Crop Protection UK Ltd (HCP) as an organisation which generates Extension of Authorisation for Minor Use (EAMU) and Emergency Authorisations for ornamental horticulture.

Chemical and biological plant protection products (PPPs) require authorisation from the Health and Safety Executive. Without HCP applying for these authorisations, up to 70% of professional PPPs used by ornamental growers could be lost, posing a significant risk to the future of UK plant and tree production.

In addition to securing the £50,000 grant from the Agriculture and Horticulture Development Board (AHDB), HCP has recently obtained two new EAMUs for the herbicide Emerger, for use on outdoor container-grown ornamentals (3341/2025) and protected container-grown ornamentals (3340/2025).

The EAMU lists numerous weeds that the product is effective against. For container-grown stock production - when applied via a horizontal boom sprayer in 200 to 400 litres of water per hectare - it should be effective against:

• annual meadow grass (Poa annua) and other grasses,
• chickweed (Stellaria media),
• hairy bittercress (Cardamine hirsuta),
• and sow thistle (Sonchus oleraceus)

The herbicide has also been evaluated in Horticulture Development Company (HDC) funded field-grown trials, including HNS 155 Nursery stock: Herbicide screening for tree seed beds, HNS 198 Improving weed control in hardy nursery stock, as aclonifen and as a coded product (HDC H44).

Charles Carr, Head of Wholesale Hillier Nurseries and HCP Board Director, said:

“This is the first new residual herbicide for use on container-grown ornamentals for many years. With the loss of Ronstar 2G (oxadiazon) and limitations placed on other products such as Springbok/Sultan 50SC (metazachlor), creating robust, long-term weed control programmes for crops has become difficult and new EAMUs are very welcome.

“It is also great news that the funding released for crop protection, following the closure of AHDB Horticulture, via HCP, is being put to good practical use to benefit the sector by identifying other potential herbicide products”.

David Denny, Director of Research and Knowledge Transfer at the HTA, added:

“It is vitally important that as many growers as possible support ongoing crop protection work, for the collective good of UK production. We are hugely grateful to our member, Darby Nursery Stock Ltd and their involvement in this trial.

“The HTA now has a growing role in facilitating research and development through projects that will boost productivity among UK growers. We look forward to sharing more information and learning from trials like this, to support a developing vision for the Nursery of the Future.”

For more information about how UK growers can support horticulture crop protection, visit: hta.org.uk/hcp