Rainfall is obviously a key driver in leaching herbicides from stubble before they dissipate, but as we all know rain can be unpredictable. Fortunately, research has shown that some pre-emergent herbicides require far less rainfall to move off stubble and into the soil where they can control germinating weeds.So, what happens when there’s no rainfall? Research has also shown that some herbicides can remain on stubble for long periods and still be active when rain occurs up to two weeks post-application (two weeks was the longest period tested). This is a pretty valuable attribute for dry sowing – as understandably growers can be reluctant to spend money on premium pre-emergent herbicides if there’s no rain in sight!This latest research by Dr Yaseen Khalil from AHRI compared the effect of rainfall on leaching of Sakura (pyroxasulfone), Arcade/Countdown (prosulfocarb) and trifluralin applied to wheat stubble.In a nutshell, Sakura was the best option in heavy stubble loads, leaching into the soil with just 5 mm rain, even where rainfall was delayed up to 14 days after application. Arcade/Countdown generally required more rainfall to leach into the soil, and only with rainfall up to seven days after application. There appeared to be little trifluralin leached from stubble, even with rainfall one day after application.Take a listen to hear more from the researcher himself, Dr Yaseen Khalil.
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