- A reduction in the likelihood of turf injury and
- They may extend weed control later into the season.
Advantages of using split apps of pre-M herbicides.
- Reduction the potential for turf injury,
- Worth considering if freely draining rootzones i.e. sand and
- Extending and improving weed control later into the season.
Considerations when using split apps of Pre-M herbicides.
With the huge amount of rain areas such as NSW and QLD have had in the last few months the performance of pre-emergent herbicides has to be discussed. So what impact does saturated soil have on how pre-emergent herbicides perform?
If you are using the split application approach a smart move is to consider increasing the rate of application. How much to increase the rate is an educated guess and depends on site-specific conditions but increasing the rate by 25% on the second preemergent application is certainly reasonable
Pre-emergent herbicide half life dependant upon soil moisture content
Approximate half-life in moist soil
Approximate half-life in saturated soil
Trials using split applications of pre-emergent herbicides.
- 2020. A trial looking at Freehand and Specticle. A split application (half rate followed by half rate three weeks later) controls weeds as effectively as the full rate, while providing extended control over the full rate.
- 2011. Equivalent summergrass control occurs when using split applications of prodiamine, pendimethalin, and dithiopyr. This is regardless of which herbicide is used for the first and/or second application.
- When applying the same amount of active ingredient, split applications are more effective. They also give more consistent control of summergrass than single applications.
- 2012. Research conducted at CAFS evaluated the effects of mowing height on the efficacy of single and split applications of preemergence herbicides for summergrass control.
- When mowed at 14mm, using split applications provides greater control than single applications.
- At 50mm, no significant differences were detected between single and split application regimes.
- Studies conducted at Penn State University using Dispatch Sprayable tank-mixed with pre-emergent herbicides give better summer grass control than pre-emergent herbicides alone.
- 2011 work shows that watering-in pre-emergent herbicides immediately after application with 2.5 to 5mm of water results in up to 50% improved summer grass control in a study on fairway-height Kentucky bluegrass.
- Contrary to what you might think, a 2014 study shows that applications of pre-emergent herbicides do not affect divot recovery.