Strike weeds early in the north and prevent resistance

Choosing and applying the right pre-emergent herbicide can be difficult, particularly if herbicide resistance is becoming a challenge in a no-till system. Join Dr Chris Preston, University of Adelaide (UA) professor weed management and WeedSmart’s Chris Davey as they explain the new Group G chemistry and de-mystifies which Group G works best for winter cropping systems.

  Dr Roberto Busi Roberto discusses what the current levels of resistance to knock-down herbicides (glyphosate and paraquat) are, resistance to new and old pre-emergent herbicides and resistance to clethodim. The results are discussed with Peter Newman by analysing the pros and cons of herbicide resistance testing and the value of herbicide efficacy and resistance testing with new herbicides coming into the Australian market from 2021.

Dr Peter Boutsalis from the University of Adelaide joins this webinar to discuss tips to optimise the efficacy of glyphosate and when and when not to use the double knock strategy. Peter also shares the latest results from the GRDC-funded random weeds survey in the Eyre Peninsula and southern Victoria and how the resistance levels in these areas have changed over the last 5 years.

Agronomists play a key role in the northern region, not only in identifying and tackling crop weeds but also in protecting chemistries. In the face of this challenge, utilising the WeedSmart Big 6 tools is showing results in tackling problem weeds. Join Crop Consultants Australia’s Director Ben Dawson, as he hosts Dr. Chris Preston and Paul McIntosh from WeedSmart and they discuss the role that agronomists can play in breaking this cycle.

There is a range of new pre and post-emergent herbicides coming to the market in the coming seasons which will broaden weed control options and use patterns. As new chemistry becomes available it is crucial for all involved to protect the longevity of any new products and minimise the risk of resistance. In this webinar, WeedSmart’s Southern Extension Agronomist Greg Condon will explore the opportunities these new herbicides provide growers and how we can protect these herbicides using the WeedSmart Big 6.

These weeds cost growers $22.5 and $1.7 million per year, respectively. Understanding the ecology of these species is vital to developing a successful weed management plan. A five-year GRDC project produced results on emergence patterns, seed bank persistence, seed shedding and competitive ability of great brome and barley grass, in Western Australia and South Australia (‘Seed bank ecology of emerging weeds’ UA00156). The project found that three to four years seed set control was needed to remove a great brome or barley grass soil seed bank. Great brome had high seed production in Western Australia and South Australia. Barley grass had much higher seed production in South Australia than Western Australia. Great brome grass and barley grass reduced crop yield, and in 2019, great brome at low to high densities reduced economic returns from a Mace wheat crop at Wongan Hills by $90-205/ha. Barley grass reduced economic returns of wheat by $67-138/ha. Data on weed ecology and competitive ability was used to update a decision support tool; the Weed Seed Wizard (WSW). The updated model was used to investigate harvest weed seed control (HWSC) as a potential management technique for great brome grass and barley grass. The modelling indicated that harvest weed seed control is a valuable tool in the management of these species, even in the years where most weed seed is shed prior to harvest. You can read Catherine’s paper here: Great brome and barley grass – modelling the long-term value of harvest weed seed control