by Bill Crabtree, Agronomist
Glyphosate resistant ryegrass is now widespread across the WA wheatbelt. Bill Crabtree explains practical strategies for improving knockdown results using glufosinate and Basher before seeding.
How to control glyphosate resistant ryegrass before seeding
After the useful TC Mitchell on 10-11th Feb for the E wheatbelt of WA, we now have TC Narelle which could drop 50 mm on much of the wheatbelt this weekend. Ignoring the supply challenges for now, let’s focus on weed control.
The good news is that herbicides have not doubled in price, but they are creeping up.
The supply of paraquat has been a challenge recently, even before this situation with Iran. Regardless of it may well be highly restricted in the future by the APVMA. It is worth considering glufosinate as an alternative, and we have amount in stock. While not as potent as paraquat, it is important to learn how to use it better as it has potential to be used as part of a double knock or even stand alone.
Work by Dr Roberto Busi demonstrated ways to improve its efficacy with different spikes at the recent Crop Updates. Both Roberto and Dr David Bowran are herbicide experts and believe that we need to learn how to use glufosinate better, as paraquat may well be removed as a tool.
With this late March rain, and probably over three days of cloud cover, it is highly likely that ryegrass germinations will proliferate in the wheatbelt. If we do get a dry April-May-June then how well you can kill these coming weeds will be critical for getting good early crop establishment. This is especially so for glyphosate resistant ryegrass which are now very common.
Here’s a few practical tools to help control glyphosate resistant ryegrass:
- Add some Basher (pelargonic acid) to the glyphosate at 2% of the rate of the glyphosate. Meaning add 20 mL Basher for one litre per hectare of glyphosate 450. This will half the brown-out time and improve the kill of resistant plants by burning the wax off the leaf’s surface. This is very useful as you will quickly know if a double knock is needed.
- Add 2-3 L/ha of glufosinate to the glyphosate – this will also speed the kill. There is some discussion that the glufosinate may limit the ability of glyphosate to get to the roots. But if the weeds are small, like 2 leaf, that might not be a problem. Likely worth a try in the problem paddocks.
- Use glufosinate a few days after the glyphosate has been sprayed – as the second knock. But remember that glufosinate likes higher water rates and humidity (>40%). High humidity is most likely within 10 days after a big rain.
Want to talk through your options? Call the 4Farmers team on 9356 5445.
Not yet receiving the 4Farmers newsletter? Subscribe here to get 4Farmers updates direct to your inbox.