A great way of getting rid of soft bodied insects like aphids and black fly without harmful chemicals, also due to the hature of this spry if used carefully there is virtually no risk to bees and other useful polinators!
Origins of Insecticidal Soap
It is thought that soap has been around since the days of the ancient Egyptians, and there are records of it being produced from tallow and beech ashes by the Phoenicians in 600 BC. It even gets a mention in the Bible: Jeremiah 2:v22.
Soft soaps have been used to control insects for more than 200 years, but recently there has been increased grower interest in using them again. There is a genuine desire at least to try substances that are safer to use than the array of chemicals on offer.
Benefits of the Insecticidal Soap
- Soft soap can kill insects, provided enough soap covers enough of the insect.
- It may also be useful against plant fungal diseases (at reduced rates).
- It can be used in a way to minimise effects on beneficial insects.
- Risk of spray scorch is much reduced in the absence of alcohol and detergents.
- It is regarded as environmentally safe, and is fully biodegradable.
- It is not persistent – an environmental and consumer benefit.
- Can be a useful water softener (and hand cleaner).
- Crop residues do not appear to be an issue.
Things you need for a basic mix
- 1 bar of dye-free, fragrance-free soap
- 1 gallon of water (bottled or otherwise pure)
- Light vegetable oil (corn, canola or safflower)
- Spray bottle or garden sprayer
Making the soap solution
- Perform a water test prior to mixing a large amount of the solution.
- Mix the concentration you intend to use in a jar of water and shake the jar.
- Wait 15 minutes. If the water stays cloudy, your water is OK to use, but if it makes a scum on the top, minerals present in your water will make the soap less effective.
- In that case, use a gallon of bottled water or boiled and cooled water sometimes works too.
- Drop a bar of unscented, white soap into 470ml of water and let it sit overnight or until enough soap has dissolved to turn the water white.
- Remove the bar of soap.
- Mix in 60ml of light vegetable oil (corn, canola, sunflower and shake well.
- It will take a bit of shaking to mix in the oil.
- The oil keeps the insecticidal soap from evaporating too quickly.
- Light vegetable oil ensures that the leaves aren't smothered.
- Fill a spray bottle or a garden sprayer that attaches to a hose with the solution you've made and spray only the affected plants.
- If possible, spot spray only the insects. It is best to spray plants in the morning so the foliage can dry during the day.
There are many commercial brands on the market, listed below are a few currently available in the UK
We do seem to be behind the USA, they are hugely found of this method of pest control.
Tips for using soaps
- When you first spot an infected plant spray directly at insects.
- Repeat next day if they still persist
- Most effective to spray in the morning on a dry day as the main destruction occurs when solution dries completely, this suffocates the insect.
There are limitations to the effectiveness of soap
Soft soap is contact action only: there is no persistence of activity on the leaf.
Repeat applications are usually necessary.
Pests vary in their sensitivity.
There is very little reliable information on the use of natural soft soap.
Properties can vary depending on the source of oil ingredients, and soap making process.
Spray applications may cause some leaf scorch (usually from rapid drying or spraying in hot conditions).
Additions of alcohol, synthetic surfactants, nicotine etc will increase risk of spray scorch.
Increased rates may be required where hard water is used for spraying (some of the soap will be used in precipitating an insoluble scum).
Soft soap cannot be readily mixed with other chemicals and fertilisers, (it is likely to affect the performance of other chemicals mixed with it, and the addition of some chemicals can alter the structure of the soft soap itself).
We can make our solutions more effective:
By adding more ingredients we can make our solutions more effective listed below are a few extras you might want to add to yours
Got any left over lemons once you have squeezed them? Well if you drop these into a sauce pan of water and bring to the boil then allow to steep for 10 minutes you will get a solution containing d-Limonene which is a great addition to your soap spray.
Chilli & Garlic:
Add a few very hot chilli to a pan of boiling water, with 10 cloves or so of slightly crushed garlic and simmer for 20 minutes to reduce liquid and concentrate mixture, insects hate the smell and will be put of infesting your plants.
Got a little coffee left over from your filter jug? Well black caffineated coffee helps to break down the wax layer on insects bodies making your soap spray even more effective.