by Bill Crabtree, 4Farmers R&D Agronomist
Glufosinate and glyphosate do not mix well for ryegrass knockdown, and the latest 4Farmers trial at Quairading shows why. Bill Crabtree walks through the results and the mix that lifted the kill to a perfect 10.
Why glufosinate and glyphosate are not a good knockdown mix for ryegrass
Thirty years ago, many in agriculture thought we had hit a brick wall with herbicide resistance, especially with ryegrass. The we discover no-till and trifluralin – a magic safe partnership. But the resistance concern revive – perhaps now due to the recent reduction in the use rate of paraquat to 231 gha. Yes, we have learnt to be smarter and use combinations of herbicide modes of action to protect all herbicides. We also saw prosulfocarb, pyroxasulfone and bixlozone help.
But for knockdowns we found a mix of glyphosate and glufosinate not work well in two trials. The latest Quairading trial (see table below) suggests glufosinate disrupts ryegrass cells before glyphosate can get into the root. This has resulted in the ryegrass kill being about as good as glufosinate alone – see treatment #2 vs #5 or #6. Changing to a K salt also gave no improvement in kill (see #5 vs #6).
In great contrast to all other mixes we adding some paraquat to glufosinate really lifted the kill in ratings to the maximum of 10 just 12 days after spraying. See treatment #7.
Some of you may have seen me talk about adding diquat to glufosinate. It might be a good mix, or, even SpraySeed (4F’s Brownout), especially where radish is the main problem weed. So, we have now just conducted that trial which will be on show for the 29th September at 10 am at the Q site (town tip).
Another very interesting find has been using shielded sprayers along with 3.75 L/ha of glufosinate. I have been staggered by the kill we have achieved between the plots. So now I have used it between the rows and again got excellent results in cold conditions. This idea came from Dr David Bowran, who worked with Mike Collins in the early 2000’s at Northam. Shields with glyphosate and paraquat or even tillage were all very poor – but glufosinate has been surprisingly safe and effective.
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