Arylex™ active in oilseed rape Back to Basics
Our Arylex™ in OSR Knowledge Hub has been created for oilseed rape growers and advisors. The new materials go back to basics on what Arylex is, how it works, how to apply it to achieve the best outcome, and practical advice on how to use it responsibly.
History of Arylex in oilseed rape
Arylex was first approved for use in cereals by Corteva in 2015.
Its effectiveness against cleavers and cranesbill led to exploration of its use in oilseed rape (OSR).
Belkar® herbicide, containing Arylex, was launched in 2019.
Belkar offers OSR growers an alternative to pre-emergence sprays, which are being used less frequently due to challenges in establishment including risks from cabbage stem flea beetle and slug pressure in wet autumns.
Growers can apply Belkar after crop establishment.
Advancing a successful herbicide legacy
Commercially available herbicides have been used in crop protection for about 80 years. Auxin herbicides were among the first herbicides introduced. They were discovered independently by American and British scientists in the 1940s and have remained foundational tools in weed management.
Corteva Agriscience has played a key role in innovating auxin herbicides helping to develop products that are more effective, easier to use and have a more favourable environmental profile. Find out more about advancing a successful herbicide legacy.
What is an auxin herbicide?
Auxin herbicides, also known as synthetic auxins, are designed to mimic naturally occurring substances in plants.
The word "auxin" comes from the Greek "auxein," meaning "to increase."
Natural auxins were first identified in the 1920s and are crucial for regulating plant growth.
In the right amounts, auxins promote plant cell growth by causing cell elongation.
Excess auxin becomes toxic to plant tissue, resulting in phytotoxic effects that can kill the plant.
Synthetic auxins were the first selective herbicides - effective only against certain weed species.
They disrupt multiple growth processes in weeds, ultimately causing weed death.
Auxin herbicides are particularly effective at controlling broadleaf weeds that commonly trouble cereal and grain crops.
What is Arylex active?
New developments within the auxin herbicide group, like Arylex active from Corteva, improve weed control, reduce resistance risk, and offer a more sustainable profile than older products.
| Feature | Details |
|---|---|
| Active ingredient | Halauxifen-methyl (Arylex active) |
| Herbicide group | Synthetic auxin (HRAC Group O) |
| Mode of action | Auxin mimic – disrupts plant growth regulation |
| Target weeds | Broadleaf weeds (e.g., cleavers, cranesbill) |
| Crops registered | Cereals, oilseed rape (OSR), others |
Arylex active is a member of the arylpicolinate family, a new structural class within the auxin herbicides.
What is unique about Arylex active?
Arylex provides a broad range of benefits:
Lower dose rates
- Arylex stands out from other synthetic auxin herbicides due to its superior efficacy at low dose rates.
- As little as 2.5gai (grams of active ingredient) per hectare can be effective on many key broadleaf weeds.
- Effectively manages ALS-resistant species like chickweed and poppy.
Can be used in a range of challenging weather conditions
- Arylex works well even when it’s cold and wet, like in late autumn or early spring. Unlike most herbicides, it is not affected much by temperature, so it can control weeds during both cold and warm periods.
Wide spray window
Farmers growing oilseed rape can take advantage of the wide spray window of Arylex active. Arylex in Belkar allows for post-emergence application from 1 September to the end of December, covering a broad growth stage range (from GS12 to GS18). This flexibility means farmers can:
- Wait for the crop to establish before spraying.
- Time applications to suit workload and weather conditions.
- Target weeds when they are most vulnerable.
Complete freedom to rotate crops
- You can plant other crops after using Arylex active without any restrictions. Arylex breaks down quickly in the soil and plant leftovers, so it’s easy to grow a variety of autumn sown rotations crops and catch crops.
Arylex mode of action
Arylex works by acting like a plant hormone called auxin. When weeds absorb it, their normal growth gets mixed up, which causes them to grow the wrong way.
As a result, weeds show twisted, curled, and odd-looking leaves and stems, then stop growing and eventually die.
Arylex is selective in cereals and oilseed rape, targeting key broadleaf weeds while being safe to the crop when used as directed.
Corteva solutions for oilseed rape with Arylex active:
Weed |
0.25 L/ha |
0.5 L/ha |
Chickweed, common |
- |
MS<8cm |
Cleavers |
S<2cm |
S<10cm |
Cranesbill, small flowered |
S<2cm |
S<8cm |
Fumitory, common |
S<3cm |
S<15cm |
Mayweed, scented |
S<2cm |
S<8cm |
Mayweed, scentless |
MS<1cm |
S<8cm |
Penny-cress, field |
MS<2cm |
MS<8cm |
Poppy, common |
MS<2cm |
S<8cm |
Dead-nettle, red |
S<2cm |
S<8cm |
Shepherds Purse |
MS<2cm |
S<10cm |
Label weed spectrum. Key: S – susceptible, MS – moderately susceptible |
||
Other useful information
- Herbicide programmes for oilseed rape - download the topic sheet here.
- Advice for blackgrass control in oilseed rape - download the topic sheet here.
- Astrokerb and Kerb Flo 500 application advice, available as a downloadable leaflet. It contains links to key information and stewardship resources. To request leaflets email: events@corteva.com.
Learn more about Belkar® and autumn weed control in OSR with Corteva herbicides
Contact us
If you would like to contact a member of the team, click here to find your local area manager. Alternatively, you can call our Technical Hotline on 0800 689 8899, email ukhotline@corteva.com, or complete our enquiry form.
