KNOCKDOWN CONTROL OF DIFFICULT WEEDS – FLEABANE, MELONS & GRASSES
Release Date 01 April 2015
Key Points
During the summer of 2014/15, SACOA set out to find the best herbicide and adjuvant combinations for controlling difficult weeds using in-field efficacy trials.
A number of independent replicated field trials have now been completed across northern NSW, southern Queensland and Western Australia.
The results have provided some interesting takes on traditional herbicide mixtures and proved the role of different adjuvant types – emulsified mineral oils, esterified seed oils, non-ionic surfactants and soyal phospholipids – in spreading and penetrating actives on leaf surfaces.
- What are the best adjuvant options for glyphosate mixtures?
- How are group A’s affected by different types of adjuvants and which is the best option?
- How effective is the double knock?
- Which adjuvants work best with paraquat?
- Are adjuvants with water conditioning properties of any benefit?
Fleabane Control – Key Findings
- In glyphosate tank mixes, high emulsifier loaded mineral oils –such as ENHANCE® or ANTIEVAP® at 1% – provide a balance between leaf surface coverage and penetration, enabling effective coverage and translocation, and proved superior to other types.
- Glyphosate activity can be reduced by the presence of Ca and Mg ions in hard water –the addition of Ammonium Sulphate will alleviate this.
- A double knock within 7-10 days of the initial application can double the efficacy of the initial treatment and prevent seed set.
- On difficult to control, stressed weeds, a penetrant type mineral oil such as ENHANCE® and ANTIEVAP® proved the most effective mix partner with paraquat in the double knock, being superior to non-ionic surfactants.
Melon Control – Key Findings
The addition of glyphosate to Triclopyr + ester mixes substantially improved control, particularly early brown out two weeks after application.
Using a high emulsifier loaded mineral oil with spreading and droplet survival properties such as ENHANCE® or ANTIEVAP® proved most effective with triclopyr alone and glyphosate mixtures.
In mixed populations (melon + eragrostis) grass weed control was not impacted when using a high emulsifier loaded mineral oil such as or ANTIEVAP® or ENHANCE® at 1%.
Figure 2: Glyphosate 1.5L + Garlon 80ml + 2,4D 500ml (lv ester 680) + Ally 5g + Enhance 1.0%, 8DAT on 16.12.14
Figure 3: Glyphosate 1.5L + Garlon 80ml + 2,4D 500ml (lv ester 680) + Ally 5g + Liberate 0.5%, 8DAT on 16.12.14
Figure 4: Untreated control, 8DAT on 16.12.14
Takeaway Messages
- For the majority of difficult knockdown weed control situations which include glyphosate, a coarse emulsion mineral oil with droplet survival and penetrant properties such as ANTIEVAP® high emulsifier loaded mineral oil with spreading properties such as ENHANCE®, provides the best balance of droplet survival, leaf surface coverage and penetration, resulting in more complete weed control.
- In a paraquat double knock –under difficult conditions or on stressed weeds a penetrant type mineral oil such as ANTIEVAP® will improve the effectiveness of the double knock.
- Soyal phospholid based products such as Liberate and COHORT 700 ® were of benefit only in hard water situations in mixtures with Glyphosate.
References
T. Boyes AgVivo Agronomy, York Feb 15
T. Boyes AgVivo Agronomy, Quairading Dec 14
Disclaimer and Copyright
This document should act as a guide only and no purchase or usage decisions should be made based on the information provided without obtaining independent, expert advice. SACOA and contributors do not necessarily recommend or endorse any products or manufacturers referred to. SACOA Pty Ltd will not be liable for any loss, damage, cost or expense incurred or arising by reason of any person using or relying on the information contained in this document. More information is available from SACOA via sacoa.com.au or 08 9386 7666, or by contacting your local reseller.
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