Master tank mix adjuvants to push pesticide performance
They’re not all muck and mystery! Master tank mix adjuvants and you’ll be able to select the right ones so you can push your pesticide performance to the max.
Vital components or expensive extras? Partnering crop protection sprays with an effective adjuvant can actually make a big difference. Use the right one in the right situation, and you could see considerable benefits. Get it wrong, and you’ll be wondering what all the hype is about.
Why do we need tank mix adjuvants?
- Poor tank mixing & incompatibility risks plant health
- High pH can lower pesticide stability
- Spray drift reduces coverage on the target
- Poor spreading restricts pesticide coverage on the leaf
- Poor penetration lower pesticide uptake in the leaf
- Heavy rainfall can leach residual herbicides
- Dry conditions can cause residual herbicides to fail
What are tank mix adjuvants?
Tank-mix adjuvants are additives that can be partnered with herbicides, fungicides, PGRs and insecticides in the spray tank to make them more efficient and effective.
Adjuvants can play an essential role in reducing yield-robbing weeds, pests and diseases. As well as improving pesticide efficacy, they can also reduce crop damage.
Partnering your crop protection sprays with the right adjuvant can be vital to maximise success and add as much as 40% efficacy and over 1 t/ha yield in a challenging situation.
Tank mix adjuvants are more effective than in-built wetting systems
As most pesticides will have an adjuvant wetting system built in to their formulation, you’ll be questioning tank mix adjuvant benefits. Why would you need more? Here’s why:
- An in-built wetting system improves pesticide coverage across the leaf but it is normally never enough
- Spraying a water-based solution across a waxy hydrophobic leaf is challenging – your spray solution will always bead on the waxy leaf so it can’t spread out properly. This means your spray coverage is always inadequate
- A good wetting system in your pesticide will help reduce water beading but you apply your pesticide at a rate/ha so you are not taking water volume in to account
- Tank mix adjuvant application rates are based on water volume, allowing you to reduce beading even further for optimal coverage
Adjuvants have a lot more to offer than just improving coverage
Adjuvants can offer a variety of benefits, from stabilising and mixing your pesticides in the spray tank, to improving the targeting of your spray application and helping it to reach its intended destination – on or inside the target. This is achieved through pH buffering, emulsifying, wetting, spreading, sticking, or penetrating. Some adjuvants also help with drift reduction.
No one adjuvant can perform all these functions to the degree you might need it in every crop. But they are are often combined at different strengths and available in pre-packaged products for specific crop uses. The trick is to use the right adjuvant product to get the vital efficacy benefits your crops need. Get that right, you’ll make your crop protection work better, last longer and give you more.
There are 2 main types of Adjuvants
Spray adjuvants can be broken down further to two types of products:
Activator Adjuvants
Surfactants & Oils
Also known as “surface acting agents,” surfactants physically change the properties of the spray solution. They can help a pesticide’s ability to emulsify in the tank, and spread and stick on the target. Oils help increase penetration through leaf cuticles and improve spreading across the leaf.
Special Purpose Adjuvants
Buffering agents, Compatibility agents & Anti-drift agents
Buffering agents are used to lower pH to stabilise pesticide activity. Compatibility agents are used to help pesticide products and other components in the tank mix thoroughly together and remain in homogenous solution. Anti-drift - Some adjuvants may have a built-in anti-drift aid, used to improve on-target placement of pesticide sprays.
So what can adjuvants do for you?
Tank mix adjuvants can perform a variety of functions to help overcome the barriers that impede pesticide performance.
Buffer pH, stabilising products in the tank
You might not realise it, but many of the crop protection products you will be applying to your fields are susceptible to alkaline hydrolysis – breakdown in high pH water. You could lose up to 50% of your pesticide’s efficacy.
Adjuvants that contain a buffering agent lower the pH of the water, preventing alkaline hydrolysis. As most spray water in England is typically alkaline, using an adjuvant that lowers pH to a pre-determined level is a good idea. This way you can create the pH that is most stable for your spray mixture so it remains stable and active in the spray tank, and can perform to its maximum potential in the field.
As a general rule of thumb, because you will likely be adding numerous products to the spray tank, it is worth keeping spray water around pH6-7 to create the most stable environment for your mixture. This can be achieved using an adjuvant such as Kantor. Glyphosate however, is most stable at pH5 and therefore will require a specific glyphosate water conditioner such as Katalyst or Volta-Ego that can make the water more acidic.
Emulsify the mix, improving tank-mixing & compatibility
Tank mixing pesticides offers flexibility, saves time and may increase effectiveness, but it can be problematic. Adding any more than 3 products to the tank increases the chance of a mixing problem. Formulation type, the temperature of the water, and the order in which you add your products all influence how well they dissolve in your spray tank. But poor tank mixing can lead to downtime whilst you fix a blocked sprayer, and reduce pesticide efficacy/safety.
Compatibility adjuvants like Kantor, aid emulsification (- the mixing of two or more products that are normally immiscible) to help reduce/eliminate physical incompatibility. They help multiple products of a tank mix to thoroughly mix together and remain thermodynamically stable in the spray tank. With more of your pesticide active ingredients in solution, more of it will be absorbed by your target plants in the field, instead of sat in the bottom of your spray tank.
Manipulate droplet size, optimising deposition & coverage on the target
Some adjuvants, such as Kantor and Backrow Max, contain anti-drift agents that help reduce drift and keep your pesticide on target.
They do this by changing the viscosity of the liquid, which manipulates droplet size. Ultimately, they bind ultra-small droplets together, reducing the number of fine spray droplets smaller than 100 microns susceptible to drift, and reduce the number of very coarse droplets which are prone to bounce. The result is a droplet with a more uniform spray angle at the nozzle that can hit the target better.
Reduce surface tension, optimising coverage & retention
Adjuvants which contain surfactants or oils, reduce surface tension between the spray liquid and the target surface, so your pesticide spray solution can spread out properly. As we explained earlier, this is crucial for coverage and retention to be maximised, on which contact herbicides and protectant fungicides depend. In fact, improving coverage and retention are key requirements for most sprays you will apply, if you want better results.
This high speed video shows an adjuvant helping the pesticide to spread out and be retained. So, how does it work?
Enhance penetration through leaf cuticles, optimising uptake
As the leaf cuticle is the biggest barrier to crop protection sprays, adjuvants that can improve penetration in to the leaf, have a lot to offer. In fact, without an adjuvant, many post-emergence herbicides cannot get in to leaves properly without one. Pesticide penetration through the cuticle is even harder when:
- Leaves are very waxy e.g. fat-hen, oilseed rape
- Plants are large – they have tougher cuticles
- Cold – wax is harder
Pesticides with high water solubility struggle to penetrate waxy leaf cuticles (- we all know water and oil do not mix well together). Adding a hydrophilic adjuvant like Sorrento will aid penetration. Pesticides with low solubility can penetrate leaf cuticles more easily, but you can enhance it using a lipophilic adjuvant such as Toil or Kantor.
This topic is difficult to get your head round but penetration in to the leaf is vital for many pesticides. It’s key for systemic herbicides, curative fungicides and PGRs. In our Challenges hub you can learn how poor penetration lowers pesticide uptake in the leaf, and which pesticides are affected. There’s also more on adjuvants and how they help get pesticides in to the leaf.
UV tracer dye showing Kantor enhancing pesticide uptake in to the leaf
How do tank mix adjuvants help residual herbicides?
Retain more residual herbicides in the top 5cm of soil, increasing uptake
Soil-acting adjuvants are crucial to help retain residual herbicides in the top 5cm of the soil. This is vital for both efficacy and crop/groundwater safety because heavy rainfall can leach herbicides out of the weed germination zone. If this happens the herbicide concentration remaining may be insufficient to control weeds properly. Worse still, your herbicides could reach the crop seed, impacting establishment, and may end up in groundwater.
How far your herbicide moves depends on its chemical properties and soil type.
Herbicides that have moderate-high water solubility and have low-medium soil adsorption characteristics are most at risk of being lost from the top 5cm of the soil following heavy rainfall. The risk is even greater in sandy soils. You can find out more on how heavy rainfall can leach residual herbicides and those most affected, here.
Research shows that adding adjuvant Backrow Max can hold significantly more herbicide in the top 5cm of the soil. It is also more effective than leading adjuvant Backrow, at creating a stronger barrier to weeds.
Increase moisture in soil, lowering dependency on rainfall for uptake
Research has shown that Backrow Max can improve the performance of residual herbicides in dry soils. This is useful because dry conditions can cause residual herbicides to fail.
Although Backrow Max won’t solve the problem of no rain for weeks on end, adding it in with residual herbicide sprays can at least reduce dependancy on it.
Likened to rain-in-a-can, trials in The Netherlands show that Backrow Max can increase moisture retention by as much as 30%.
Most recently in spring barley, we have seen improvements of nearly 20% weed control, albeit from a low base.
How to select the right tank mix adjuvant
Choosing the best adjuvant to do the job can be confusing as there are so many products available.
Our top tips on adjuvant selection
Always read the pesticide label. Advice may be given that must be followed on what type of adjuvant to use/avoid.
Always buy reputable products produced by a trusted manufacturer. Whilst adjuvant manufacturers may offer many of the same functions, product quality and adjuvant technology varies dramatically. Check there is data and evidence to back up any claims.
Using an adjuvant is not always necessary. Think about your target, the pesticides you are applying and what they need to do and weaknesses they have. In good conditions, you may not need and adjuvant and you might therefore not see a benefit. On the other hand, there may be weaknesses in your spray preparation, application and delivery that can be improved.
Although different adjuvants can perform a variety of different functions and significantly improve pesticide performance, no one adjuvant can perform every function for every situation. Make sure you have a good knowledge of the adjuvant you are using and it’s the right one for the job.
Finally, do a small test on your farm. You won’t know unless you take the leap to find out.
The Adjuvant Experts
As the UK’s leading adjuvant manufacturer, we have a range of innovative solutions to help you get the most from every application.
Our solutions to help you push pesticide performance
Backrow Max – The new and improved Backrow thats helps take residual herbicide performance to the max, come rain or shine.
Kantor – The only 1-can adjuvant solution to benefit the full mixing and spraying process end to end, making it your essential partner for unbeatable chemistry.
Sorrento – The performance partner for post-emergence herbicides. Ensures reliable control of the toughest weeds.
Toil – The trusted methylated rapeseed oil that helps maximise the performance of graminicides.
The above solutions are available to purchase through Agrii in the UK.
Learn more about Water Conditioners & Drift Retardants
Is hard water and high pH causing havoc with your tank mixes? If it is, you’ll need to condition hard water and correct pH with a water conditioner to maximise pesticide effectiveness.
Learn more 
Timely on-target spray application is a key objective for effective pesticide applications, but even on a “good” spray day, drift may set you back. Adding a drift retardant in to the spray tank will help combat drift and keep your sprays on target.
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