After an intensely wet year, soil repair and giving careful consideration to the weather implications on herbicide performance will be vital to secure pre-em efficacy and get crops up and away weed-free this autumn.
The pre-emergence herbicide programme is often the most crucial part of the chemical weed control strategy to avoid reliance on less effective contact chemistry post-emergence. But by their very nature, soil-acting pre-emergence residual herbicides are dependent on good soil structure and favourable weather conditions following application. The key is to keep them active in the weed germination zone for as long as possible. Being aware of how your herbicides will be affected by soil health and the weather this autumn, means there are steps you can take to help avoid the issues, so you can get more from your pre-ems and get your weed control strategy off to the strongest start.
Here’s some tailored advice on optimising pre-emergence herbicide performance this autumn:
Key Points:
- FIX POORLY STRUCTURED SOILS
- DON’T UNDER-ESTIMATE THE WEATHER
- BACKUP YOUR PRE-EMS WITH BACKROW MAX
Step 1: FIX POORLY STRUCTURED SOILS
Aside from suboptimal crop performance and growth, poor soils can significantly reduce herbicide efficacy. Examine soils and identify areas that need repairing ahead of drilling to avoid the following:
Soils with surface crust – are prone to surface run-off which can wash away applied herbicides before they even infiltrate the soil.
Compacted layers – lead to poor water and herbicide infiltration, preventing herbicides reaching the weed germination zone.
Lack of porosity – there could be insufficient soil water at depth to desorb herbicides from soil particles efficiently for weed uptake.
Poorly structured soils – especially sandy soils with low organic matter are prone to leaching in wet conditions putting crop and groundwater safety at risk.
Creating a well structured soil, characterised by good tilth, no compaction and good porosity, supports pre-em efficacy:
A firm fine tilth – will enable good distribution of the residual herbicide when it is sprayed across the soil surface.
Removal of any compacted layers – is vital to allow good water and herbicide infiltration into the soil, down to the weed germination zone.
Healthy soils with good porosity – not only keeps the soil aerated for your crops, it also directly affects the volume of water your soil can hold on to. This will support crop health and residual herbicide efficacy.
Step 2: DON’T UNDER-ESTIMATE THE WEATHER
With residual herbicide performance at risk from suboptimal weather conditions, you could be losing valuable weed control if soils become excessively wet or excessively dry. To maximise the effectiveness of residual herbicides, understanding and considering weather conditions is crucial. Here are key weather-related factors to keep in mind:
Ensure adequate moisture for herbicide activation
Residual herbicides typically require moisture to activate them – ie move them from the soil surface to the weed germination zone 5cm lower down. Make sure there is sufficient soil moisture after application to facilitate this process.
In a dry spell there maybe insufficient moisture for activation to occur. Where necessary, consider delaying your application, especially if there is insufficient moisture for weeds to germinate shortly after application.
Avoid heavy rainfall immediately after application
Apply pre-emergence herbicides when rain is forecasted but avoid periods of heavy rain to ensure herbicides have sufficient time to bind to soil particles.
Heavy rainfall shortly after application can wash away the herbicide, reducing its concentration in the weed germination zone and making it less effective against target weeds. In adversely wet conditions, there is also the risk of herbicides moving to the crop seed and reaching groundwater, particularly in light soils.
Stay informed about local weather conditions and adjust your application timing accordingly.
Apply during calm conditions
Choose days with low wind speeds to minimise drift and ensure even herbicide application across the soil target.
Windy conditions during application can cause drift, leading to uneven distribution of the herbicide and reduced effectiveness on target areas.
Step 3: BACKUP YOUR PRE-EMS WITH BACKROW MAX
An effective residual herbicide adjuvant like Backrow Max can both enhance herbicide performance and increase the safety of the application in adverse conditions, leading to more reliable control of weeds and improved crop establishment.
Download our latest Backrow Max guide here for more info or keep reading below.
Utilise Backrow Max to get more from your pre-ems
By incorporating residual herbicide adjuvant Backrow Max into your pre- and peri-emergence tank-mixes, you can significantly improve the reliability of your pre-ems during adverse weather conditions. Here’s how it can help:
Dry conditions: Backrow Max helps maintain soil moisture levels in the soil, reducing dependency on rainfall for herbicide activation. This also aids the consistent release and uptake of herbicides into germinating weeds leading to more effective weed control.
Wet conditions: Backrow Max helps bind herbicides better to soil particles, reducing their movement out of the weed germination zone. This prolongs herbicide concentration and longevity in the weed zone following heavy rainfall, increasing both herbicide effectiveness and residual activity.
Backrow Max reduces the risk of herbicides reaching the crop seed damaging plant health, and minimises contamination to watercourses. It safeguards crop establishment and is a valuable water stewardship measure.
Drifty conditions: Backrow Max reduces the number of fine spray droplets under 100 microns which are the most susceptible to drift. It also reduces the number of very coarse spray droplets prone to bounce, creating a more optimal spray droplet for pre-emergence application. This results in more even spray distribution and coverage across the soil surface creating a more effective barrier to weeds.
WHY FARMERS CHOOSE BACKROW MAX TO SECURE THEIR FIELDS
Prolonged protection
Achieve consistent, longer lasting protection in suboptimal seedbeds and spraying conditions.
Enhanced establishment
Prevent herbicides causing crop phytotoxicity.
Sustainable practices
Protect off-targets by reducing chemical movement to nearby fields and watercourses.
Proven results with Backrow Max
Improves spray deposition and coverage – Up to 35% reduction in drift prone spray droplets; optimises droplet size with flat fan and low drift nozzles.
Increases herbicide retention in (top 5cm of the soil) the weed germination zone – Improvements in all studies 0-5cm: 7% more clomazone; 8% more pendimethalin; 6% more Luximo; 7% more nitrate.
Increases moisture retention in dry seedbeds – 33% increase in water retention recorded in Lysimeter studies in the Netherlands.
Enhanced residual activity – In cereals up to: +17% black-grass control; +17% ryegrass control; +18% brome control.
Boosts effectiveness in dry seedbeds – In cereals up to: +22% black-grass control; +18% annual meadow-grass control.
Reduces crop phytotoxicity and improves crop establishment – Phyto trials: 20% reduction in chlorosis and increased wheat emergence by up to 29 plants per sqm.
STRENGTHEN YOUR PRE-EM PROGRAMME
Incorporate Backrow Max into your pre- and peri-emergence tank-mix to get more from your pre-ems this autumn. For more info:
Download our latest guide here – for independent trials results with the latest herbicides, and farmer case studies. You’ll also find an extensive list of approved crops.
Please get in touch with Stuart below if you require any technical assistance.
Backrow Max can be purchased through Agrii in the UK.