Spring cereals tend to sit in two camps so far this year – those drilled before the Easter deluge and those that have either only just been drilled or are still to be drilled! Weed control may not be top of mind in these crops with the backlog of work, however, we hope that the quick guide below gives some useful food for thought.
The use of residuals in spring cereals is increasingly popular, primarily driven by the need for grass weed control. There is a strong geographical variance, ranging from 5% of the crop treated with a residual in some areas, to 80% in others. Whatever the products used, efficacy depends upon a number of aligning factors, such as seedbed conditions, appropriate moisture levels, weed seed germination profile, product rate, etc. Results from trials, and feedback from many agronomists, show that a number of important weeds can come through a residual herbicide, such as poppy, fat hen, black bindweed and fumitory. This means that the use of a follow-up contact spray after the use of a residual is commonplace. Products containing Arylex are well suited as follow-up sprays.
Those that drilled spring cereals before Easter were unable to get back to spray and now weeds have passed growth stages where residuals are effective. The more recently sown cereals are moving so fast in the ideal growing conditions, resulting in both crop and weeds going beyond the optimum timing. This means that contact herbicides such as Arylex products will be the main weed control approach for many spring cereal crops.
Post-emergence broad-leaved weed control
Where a residual has not been used, controlling the broad-leaved weeds early is a priority. Data from 38 trials in spring barley, where no residual had been used, showed yield increases from herbicides being greatest when applied between GS12 and 25 of the crop, while applications from GS24-32 did not yield significantly higher than the untreated. Yield however is not the only component to consider as many weeds can impact on harvesting. It is also important to consider weed emergence patterns as post-emergence weed control depends on the weeds being present at the time of application.
The tools available for broad-leaved weed control in spring cereals have changed in recent years with the most significant being the loss of the Ioxynil. At the same time new herbicide introductions have given new tools
- Wide spectrum of weeds controlled including fumitory, fat hen and black bindweed
- Reliable control in variable weather conditions
- Tank mix compatibility
- Wide windows of application
- Low carry-over risk to following crops
Control of ALS resistant weeds including poppy and chickweed
Using the products successfully will depend on knowing the weeds present and mixing with other herbicides to fill gaps:
The ideal target size of weeds is from 4-6 leaves. Dose rates of the Arylex products should be adjusted according to weed size and should not be used as a ‘rescue treatment’ when weeds have passed certain weed sizes/growth stages. See product details for more information.
*Where ALS resistant poppies are present at a high population, every percentage-point of control is critical and in these situations, Trezac is the product of choice.
Post-Emergence grass weed control
In spring barley, post emergence grass weed control is principally based around Axial (Pinoxaden) for wild oats. Applications typically take place at flag leaf emergence of the barley. Zypar, Pixxaro and Trezac are fully supported in a tank mix with Axial plus adjuvant.
In spring wheat, we now have approval for Broadway®Star (at 200g/ha), which delivers control of a wide range of broad-leaved weeds as well as activity on wild oats. The timing of application is between growth stages 23 and 32 of the spring wheat. For more information our tech sheet has details.
For more information click on the links below: