Diluting Concentrated Pesticides 

It is perhaps because it seems so easy that some times not enough care is taken and mistakes are made. Remember that concentrates are by their very nature more active than the final spray and are therefore to be handled with some respect. Here is a simple guide to diluting concentrates for spraying, safely, with least waste and best efficacy.

1. Protect yourself

Put on waterproof gloves and eye protection. We also advise wearing face mask, overalls and gumboots or similar during mixing and spraying.

2. Prepare the product
Liquids - Shake product well before use and let any foam settle.
Powders/granules - Shake product gently to loosen and let settle for five minutes.

Most sprayers have measuring marks on the outside. If your sprayer does not, then using a 1 litre measuring jug, add 1 litre at a time to the sprayer and mark each level with a an indelible marker.

Using a measuring jug and sprayer >

• If possible use a 1 litre measuring jug dedicated to the type of product to be used i.e. garden insecticide/fungicide, selective weed killer, non-selective weed killer, household insecticide, moss and mildew killer, etc. Rinse out measuring jug and sprayer with clean water.
• Quarter fill the measuring jug with clean water. Carefully add required amount of concentrate or powder/granules to the water in the jug (if powder/granules- stir until dispersed).
• With clean water rinse out the measuring cap/cylinder into the jug at least 5 times. Add clean water to the jug until the level reaches 1 Litre.
• Add mixture to sprayer. Using measuring jug, add more clean water to the sprayer until the required water level is achieved.
• Using a jug is unlikely to cause foaming. If foaming occurs, slow the addition of water. Let liquid sit until foam subsides before completing filling. Do not let foam spill from sprayer.

Sprayer only >

• Rinse sprayer with clean water.
• Add 1 litre of clean water to the sprayer. Carefully add required amount of concentrate or powder/granules to the water in the sprayer (if powder/granules- stir until dispersed).
• Using clean water, rinse out the measuring cap/cylinder into the sprayer at least 5 times. Add clean water to the sprayer until the level reaches 5 Litres.

Note: If foaming occurs, slow the addition of water. Let liquid sit until foam subsides before completing filling. Do not let foam spill from sprayer. 

3. Clean sprayer, jug and stirrer

After use rinse the sprayer, jug and stirrer out with clean water at least three times. It is good practise to pump clean water through the spray nozzle to clear product from sprayer head and tube.

If a diluent (solvent) other than water is used, the equipment should be cleaned with an appropriate cleaner such as household washing up liquid. It is also recommended that sprayer seals are checked and lubricated with petroleum gel, grease or similar to keep in good order.

Mixing with diluents (solvents) other than water

Some Kiwicare products are not formulated to mix with water e.g. NO Borer Wood Protection Concentrate and some products can be mixed with other diluents for better effectiveness, e.g. NO Spiders Total Protection mixed with turpentine or Weed Weapon Woody Weeds mixed with diesel for control of re-sprouting stumps. In these case the process is similar to that described above but using the appropriate solvent.

• Watch our videos on how to mix and dilute spray concentrates

This table will help you get the best out of concentrates, stay safe, reduce spills and save you money.

Table of Dilution Rates

Liquid - Label Rate

Powder/Granule - Label Rate

*Ratios - Some products specify a ratio of diluent (water or other solvent) to concentrate. In this case add the two numbers together where the total will be the final volume. e.g. 4:1 ratio is 4 Litres water plus 1 Litre concentrate equals 5 Litres final solution.

**When the ratio becomes high, e.g. 20:1 or higher, it is reasonable, for the sake of ease of calculation, to add 1 part concentrate and make up to 20 parts final solution instead of trying to calculate 1/19th of the final volume or measure 21 parts. So the volumes of concentrate shown in the table above for 20:1 ratios are strictly speaking those for 19:1 ratio.

David Brittain
Kiwicare