Pest & Disease Management - Adjuvants

Adjuvants are substances that can be added to the spray tank to modify a pesticide and/or spray mixture's performance.

If there are application issues with the equipment or product, then adjuvants can help to overcome them, providing enhanced efficacy. 

Although adjuvants are not classed as pesticides, they need to be registered with the Chemicals Regulation Division because they are modified chemicals.

If you know your particular needs and the limitations of the products you intend to use, adjuvants can increase the efficiency of pesticide applications. Their correct use does require some in-depth knowledge.

Adjuvants can minimise or eliminate issues such as incompatibility, instability, foaming, drift, evaporation, volatilisation, degradation, adherence, penetration, surface tension and coverage. They are designed to perform functions such as wetting, sticking, spreading, emulsifying, buffering and dispersing. They may also have some positive effect on managing water hardness. However, no single adjuvant can do all these things.

Make sure the adjuvant has been thoroughly tested and proven - test new products on a limited crop area before full-scale use. Certain pesticides need certain types of adjuvants so check the product label and only use the correct type. Do not substitute an anionic or cationic type of surfactant when a non-ionic type is recommended. For nursery crops it is usually the non-ionic types that are most suitable.

Check adjuvant labels carefully - pesticide labels need checking too, along with any information detailed in their EAMUs, to make sure an adjuvant is suitable for the site, the crop you plan to spray, the target pest, your equipment and, of course, the pesticide you plan to use. Some pesticides have additional restrictions on product choice, when using an adjuvant, to limit the risk to the environment and in some cases you are advised to reduce the pesticide rate when using an adjuvant.

Many pesticide products already contain an adjuvant, which reduces the need to add one, but not all product labels state whether they are included. If a pesticide is formulated properly for your crop, using a wetter-spreader may not give better spreading or coverage. Rather, it could increase run-off, reduce deposit and even severely damage the target plants.

Use only adjuvants manufactured and marketed for horticultural uses. Do not use industrial products or household products with pesticides because they may contain other substances that may interfere with pesticide performance and may not be approved. Adjuvants are generally categorised according to function and the main groups are as follows:

Acidifiers

These lower the pH of a pesticide spray tank solution. This is particularly important should you use a hard water for spraying. Lowering the pH of the spray solution to that nearer the leaf pH helps penetration of systemic products.

- Acidifiers include Guide, Li-700, Spraymac and X-Change.

Buffers

These tend to stabilise the pH at a constant level. Most pesticide solutions are stable between pH 5.5 and 7.0. Pesticides diluted with hard water do not always penetrate the tissue so effectively.

- Buffers include Companion Gold.

Compatibility agents

Products that facilitate more uniform mixing of liquid fertiliser and pesticides, or mixing of two or more pesticides in a tank mix with any liquid carrier.

Crop oils

Petroleumor vegetable-based product generally containing two per cent emulsifier and 98 per cent oil. These can aid product absorption by the plant because they soften the cuticle. They can also increase risk of leaf scorch in hot, sunny conditions.

De-foaming agents

Some pesticides cause foaming in the tank. This can be the result of the type of surfactant used or tank agitation. A de-foaming adjuvant can suppress both surface foam and trapped air in the spray mixture.

- De-foamers include Companion Gold and X-Change.

Drift retardants

Products used in spray mixtures to reduce drift.

Plant penetrants

Products that enhance a liquid's ability to penetrate plant roots, leaves and stems. They can be quite specific to plant types. Some herbicides and translocated fungicides can be enhanced by penetrants.

- Penetrants (for general crops) include Guide, Headland Fortune, Headland Intake, Katalyst, Li-700, Torpedo II and Wetcit.

Stickers

Adjuvants that increase the adhesion of fine solids to the leaf surface. They also decrease the amount washed off by rain or irrigation, reduce evaporation and, in some cases, reduce the ultraviolet degradation of a pesticide.

- Stickers include Addit, Asu Flex, Bio Syl, Biofilm, Biothene, Bond, Broad Flex, Companion Gold, County Mark, Designer, Desikote Max, Eco-Flex, Elan Xtra, Gateway, Gly-Flex, Gly Plus A, Grenadier, Headland Guard Pro, Impala, Intracrop Agwet GTX, Intracrop Boost, Level, Meco Flex, Nu Film P, Profit Oil, Sprayfast, Spray-Fix, Spraygard, Stika and Zigzag.

Surfactants

These modify surface tension, can influence the wetting and spreading of liquids and can modify dispersion, suspension or precipitation of a pesticide in water. For a spray droplet to perform properly it must be able to wet the foliage and spread evenly over the surface. These products alter the size of the droplet and enlarge the area of coverage, which is important for waxy and hairy leaves.

There are non-ionic surfactants (no electrical charge), anionic surfactants (negative charge) and cationic surfactants (positive charge). Non-ionic products are mostly used with systemic products in horticultural crops to help penetration. Cationic products are mainly for herbicide purposes and are not to be used generally.

- Non-ionic surfactants include Activator 90, Mixture B NF, Intracrop Questor, Intracrop Saturn, Planet, Solar, Spraymac and X-Wet. Cationic surfactants include Jogral and Ryda.

Thickeners

Adjuvants that increase the viscosity of a spray mixture, which increases the droplet size and reduces drift. These would normally be used on large-leafed tree and shrub subjects.

Fully updated by Dove Associates

Use plant protection products safely. Always read the label and product information before use. Dove Associates shall in no event be liable for the loss of or damage to any crops or biological control agents caused by the use of products mentioned.


Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Sign up now
Already registered?
Sign in

Before commenting please read our rules for commenting on articles.

If you see a comment you find offensive, you can flag it as inappropriate. In the top right-hand corner of an individual comment, you will see 'flag as inappropriate'. Clicking this prompts us to review the comment. For further information see our rules for commenting on articles.

comments powered by Disqus

Read These Next

Business Planning - Staff are your greatest asset

Business Planning - Staff are your greatest asset

An effective strategy to retain staff is the best way for any business to avoid a potential recruitment crisis, Neville Stein advises.

GroSouth 2017 update

GroSouth 2017 update

First-time and established exhibitors are preparing to showcase products and services at this year's show in West Sussex, Gavin McEwan reports.

Pest & Disease Factsheet - Vine weevil

Pest & Disease Factsheet - Vine weevil

Avoid costly damage by this serious plant pest.


Opinion... Pepper breeders' wealth of knowledge

Opinion... Pepper breeders' wealth of knowledge

Peter Seabrook looks forward to garden centre pepper-tasting weekends.

Opinion... Shining a light on trading with Europe

Opinion... Shining a light on trading with Europe

Accurate figures are notoriously difficult to get at, but without doubt the UK imports a great deal of its ornamental plant requirement.

Opinion... Unbeatable delight of quality plants

Opinion... Unbeatable delight of quality plants

Viewing top-quality plants, both growing and on sale, always gives me pleasure.


Follow us on:
  • Facebook
  • LinkedIn
  • Twitter
  • Google +
Horticulture Jobs
More Horticulture Jobs

Tim Edwards

Boningales Nursery chairman Tim Edwards on the business of ornamentals production
 

Read Tim Edwards

Ornamentals ranking

Top 30 Ornamentals Nurseries by Turnover 2017

Top 30 Ornamentals Nurseries by Turnover 2017

Tough retail pricing policies and Brexit opportunities drive the top 30 growth strategies.

Pest & Disease Tracker bulletin 

The latest pest and disease alerts, how to treat them, plus EAMU updates, sent direct to your inbox.

Sign up here

Are you a landscape supplier?

Horticulture Week Landscape Project Leads

If so, you should be receiving our new service for Horticulture Week subscribers delivering landscape project leads from live, approved, planning applications across the UK.

Peter Seabrook

Inspiration and insight from travels around the horticultural world
 

Read more Peter Seabrook articles