|Version 2||Date January 2020||Reference 76|
Adjuvants can greatly assist in improving the performance of summer fallow herbicides by:
|Graph 1 :The addition of Enhance increases the VMD in spray solutions whilst non-ionic surfactants such as Wetta 1000 can decrease the VMD. (Source: USDA droplet survival study SACOA May 2014)|
Maintaining correct droplet size is crucial to reduce drift and ensure good coverage on target leaf surfaces. Nozzle and adjuvant type, operating pressure, travel speed and environmental conditions all impact on droplet size. Enhance will increase overall droplet size and reduce the number of small driftable droplets. In contrast, non-ionic surfactants will reduce droplet size and increase drift. Glyphosate and many paraquat formulations contain inbuilt non-ionic surfactants – so using them without an oil-based adjuvant can cause drift issues and efficacy loss.
|Image 1: Spray coverage of various adjuvant types in a typical summer herbicide mixture with AI110015 nozzels @ 3Bar and 100L/Ha water. Temp: 30.4oC, RH 32%, Wind speed 11.0km/Hr, Delta T 11.5 Coverage analysis using Snapcard® water sensitive paper analysis app. (Source: SACOA internal trial December 2014).|
Once a spray droplet reaches a target surface – droplet survival becomes critical in ensuring herbicide actives are able to penetrate through the leaf surface get to their site of activity within the cell. Methylated seed oils such as Plantocrop are excellent for assisting leaf surface penetration, particularly in mixtures with GRP A’s and paraquat.
SACOA’s mineral oil based adjuvant, Enhance, has become the fallow spraying adjuvant of choice in many cropping areas – offering the benefits of:
SACOA’s methylated seed oil based adjuvant, Plantocrop, is ideal for use with GRP A herbicides such as clethodim and haloxyfop which are becoming increasingly important for managing grasses such as Feathertop Rhodes and Barnyard grass, particularly where glyphosate resistance is a concern. GRP A’s are classified as lipophilic and are therefore relatively slow at entering into leaves. Plantocrop increases the rate of GRP A leaf uptake particularly through cuticle and wax layers. When used as an adjuvant with paraquat in the double knock, Plantocrop will improve leaf surface coverage by reducing drift and facilitating leaf uptake. The double knock should always be applied within 7-10 days of the initial GRP A application, to ensure enough time for GRP A translocation but before any weed recovery can start. Be aware also that a double knock is a legal requirement of using GRP A’s in a fallow situation.
|Graph 2: Adjuvants such as Enhance and PLANTOCROP increase the droplet survival time on leaf surfaces, enabling time for the active ingredient to enter. (Source: USDA droplet survival study SACOA May 2014)|
|Image 1 : Fleabane (Source: SACOA).|
|Graph 3: (Source: T. Boyes AgVivo Agronomy, York Feb 15)|
|Image 2: Feathertop Rhodes (Source: SACOA).|
|Graph 4: (Source: Kalyx Dalby 12/2/2015 (KA14-1041 Adjuvants and Oils for summer fallow weed control)|
|Graph 5: (Source: Kalyx 13.5.2014 – KA13-828 Control of Awnless Barnyard Grass Narrabri)|
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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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