Case study: Jock Coupland– control of ryegrass and black oats in a retained stubble system.
Property owners: Jock and Trini Coupland, “Wardry” Condobolin.
Property size: 2800 ha
Enterprises: Dryland wheat, lupins, canola, irrigated cotton and cattle.
Soil and pH: red soil to river clays with a pH of 5.2 – 7.
Jock doesn’t have a fixed rotation with his dryland farming, rather it depends on seasons and markets. His irrigation crops consist of wheat in winter and cotton in summer and paddocks are rotated between the two.
His cropping and livestock enterprises are kept separate and cattle are not grazed on stubbles or fallow.
Rye grass and black oats control:
Jock has found with his dryland cropping that although populations of rye grass are black oats are now lower than they were fourteen years ago when they began farming at “Wardry”, the weeds are becoming more difficult to control within a retained stubble system and with the emergence of Group A chemical resistance and possible rye grass resistance of Group B chemicals.
He is performing tests this year to confirm his suspicion of this resistance.
Jock is now rotating with TT canola and lupins to assist with control and is making headway on those harder to control weeds, as well as controlling weeds along fence lines and irrigation bays.
He is very keen to begin narrow windrow burning and has plans to set up his header for next year to achieve that.
Until then he will continue to use broad burning as a tactic if necessary, it’s not something he does often but sees it as another tool to be utilised in the arsenal against weed resistance.
Jock has also started using Treflan as a pre-emergent attack, it’s not as easy to incorporate into the soil in a stubble retained system but he feels he now has the system (with 12 inch spacings) that allows him to achieve good results.
Another strategy Jock is considering post-harvest is baling stubble for the mushroom market. He was geared to that last year but the contractor was unable to do the job. It’s a strategy he’ll use in the future.
Having a background in agronomy has made it a little easier for Jock with regards to having up to date information about weed resistance and herbicide resistance, but actually applying that knowledge as a farmer is not the easiest thing to do as Jock readily admits.
He also seeks advice from other agronomists and employs an agronomist to monitor his cropping program.
With his summer cropping program of irrigated cotton Jock notes the cultivation needed for preparation causes the burial of weed seed, but also the destruction of seed – there’s a lot going on. Glyphosate and other broad spectrum chemicals are more widely used in this facet of his cropping program.
He is very aware of maintaining clean irrigation channels as he has discovered resistant rye grass there. If possible he’ll chip these weeds by hand.
Key issues for control of rye grass and black oats:
Jock’s advice for farmers noticing resistance emerging is to first get tests done around harvest time on mature weed seeds to confirm that resistance so they know what they are dealing with. In other words, identify the problem first.
If resistance is confirmed crop and chemical rotations have to be adopted and every tactic available should be utilised, they are all valuable tools in the fight against resistance.
Jock also recommends looking at the Ryegrass Integrated Management System (RIM) as an online tool to identify herbicide strategies in a virtual world before applying those tactics in real world conditions.