Five questions to help make every spray count - Elders Rural Services

Five questions to help make every spray count

Through their Target 100 program, Sinochem are helping to equip growers with the information needed to achieve better outcomes in the field. In conjunction with Sinochem, we have answered some of the most commonly asked questions about weed control using industry research.

What is the impact of not controlling one Ryegrass plant per square metre? 

In excess of two million seeds per hectare.

Dr Michael Walsh from the Australian Herbicide Resistance Initiative travelled the
entire cropping zone of Australia comparing Harvest Weed Set Control (HWSC)
tools at 24 sites in wheat crops. In this research, Michael measured ryegrass seed
set. On average, across all of the 24 sites there were 10 ryegrass plants per square
metre in crop, and they set an average of 210 seeds per plant.









What is the optimum time between glyphosate and paraquat application in a double knock?

1-5 days.

Under normal conditions ryegrass plants need a minimum of one day to get a lethal dose of glyphosate. However, work conducted by Dr Chris Preston shows annual ryegrass survival significantly increases after the 5-day mark. Actively growing annual ryegrass plants will become stressed 5 days after a glyphosate application as they metabolise the glyphosate, which can reduce the uptake of paraquat.










How fast is too fast when spraying glyphosate?


There are limitations to good application and efficacy with high ground speeds. Travel speed and water volume have the greatest impact on achieving good coverage. Higher working speeds also result in increased dust in wheel tracks and losses to the environment leading to poor efficacy. According to Bill Campbell of Farmanco, with increased speeds, generally greater than 20km/hr, and especially above 25km/hr, there will be fewer droplets retained on targets.












What is the ideal boom height when spraying in stubble?

Sprayer height should operate at 50cm above the target weeds or the top of false targets (i.e. stubble) – whichever is taller.

The biggest loss of herbicide efficacy in stubble situations is interception of the spray droplets by the standing stubble. Having the sprayer height high will also significantly increase drift potential; a boom operating at 1m above the ground has nearly 10 times the potential drift of a 0.5m high boom*.
In order to maximise weed control, ensuring correct sprayer set-up is key. Identify the target weed first (e.g. grass vs. broadleaf, age) in order to determine what droplet size, water rate and product rate should be used to fallow spray in stubble.







Are there different types of ryegrass resistance?

There are six known mechanisms of glyphosate resistance, three have been identified in ryegrass.

There are various tools that can be used to manage glyphosate resistance including herbicide rotation, double knock with paraquat, cultivation, and several weed seed control methods. The type of resistance also has a bearing on the effectiveness of the glyphosate spray.

This information is provided in conjunction with Sinochem’s RoundUp ULTRA MAX Herbicide which has shown outstanding results in trials to maximise weed control.



® Roundup, Roundup Ultra and Kelpie are registered trademarks of Monsanto Technology LLC used under licence by Sinochem International Australia Pty Ltd. *Always use product according to label instructions. Any subsequent weed management strategies should involve an integrated weed management (IWM) approach to minimise development of glyphosate resistance.