The ambition of gardening without using pesticides is a noble one. But most people leave their best intentions behind once they’ve lost an entire crop to aphids or other bugs, wasting weeks of work to a few days of feeding. Fortunately, using insecticides doesn’t need to mean spraying your garden with noxious synthetic chemicals that linger in the environment with widespread side effects. It’s possible to make your own fully organic spray treatment that’s lethal to aphids, caterpillars and most other soft-bodied insects but that also biodegrades within a few days of use, leaving no harmful traces behind. The spray is based on toxins derived from the variety of chrysanthemum known as pyrethrum, and here’s what to do. Commercial products based on pyrethrum’s toxins are available, but many are made from synthetic chemicals and contain potentially unwanted ingredients such as copper sulphate. Making your own spray from homegrown plants guarantees a fully organic result with ingredients you choose. The starting point of the homemade insecticide is the flower heads of Chrysanthemum cinerariifolium, AKA pyrethrum, a member of the perennial daisy family. The petals contain a high concentration of pyrethrin, the active ingredient in the spray. You can also use a similar plant called Painted Daisy (Tanacetum coccineum), which produces dramatically colourful flowers but a lower concentration of the toxin.
To grow the pyrethrum chrysanthemum, choose a sunny spot with moist but well-draining soil. In spring, sow the seeds direct, 4mm deep and 35cm apart, or raise indoors as seedlings before planting out with the same spacing. Pyrethrum can also be grown in medium-sized containers (at least 30cm across). Germination typically takes 7 to 10 days, with the plants reaching maturity after about 4 months. Bushy growth can be encouraged by pinching out the earliest flower buds, and the flowering season can be prolonged by removing flowers as they start passing their best, which will also give you more opportunities for making the pyrethrum spray.
Harvesting the Flowers
To make the spray, cut off whole flower heads when in full bloom, and hang them to dry in a cool, dark place. Flowers have the highest concentration of pyrethrin when the first petals have opened. Once fully dried, the flowers should be stored in an airtight container out of direct light or heat, or even in the freezer (taking care not to contaminate foodstuffs). In ideal conditions, the whole flower heads will retain their insecticidal toxicity for up to six months after the flowers are dried. However, once the spray is prepared, it will degrade and lose its strength in a matter of days. Just before you want to spray your plants, grind up the flowers into a smooth powder, ideally wearing gloves and a protective mask to rule out any potential allergic reactions. Different ratios can be used to achieve different strength sprays, but a good starting place is to combine half a cup of the powder with a little liquid soap (about 10ml) to help it dissolve, then mix with 1 litre of plain water to reach a sprayable consistency. Transfer to a garden sprayer and use as needed.
- 1/2 cup pyrethrum flower powder
- 10ml liquid soap (or 10g soap powder)
- 1 litre water
A Quicker Method If you have fresh pyrethrum blooms to hand and have an urgent need for insecticide, a second method removes the drying process and only takes a day or so to make the spray. Simply combine the freshly picked flower heads with 70% isopropyl alcohol, using around 30ml of alcohol per 250g of flowers. Leave to soak overnight, then drain through muslin or a clean dishcloth. Dilute the extract to a quarter strength using cold water, and transfer to your garden sprayer.
Using Your Homemade Pyrethrum Spray
Whichever method you use to make the spray, use it as quickly as possible as the solution will begin to biodegrade in sunlight. This short active life makes it safe to use on the vegetable patch, but it’s best to wait up to a week before harvesting and also wash your produce well before eating to be completely on the safe side. Although pyrethrum isn’t dangerously toxic outside the insect realm, it’s always best to use it with caution, particularly with homemade preparations where the strength isn’t precisely known. Use a mask and protective clothing when spraying, gently spray directly onto the target rather than misting a whole area, and keep children and pets away during spraying and ideally for a day or two afterwards. The spray kills insects almost instantly on contact, so you don’t need to go overboard when treating the targets. Use a light hand rather than soaking your plants, and be aware you may need to apply a second spraying a few days later if the infestation still isn’t controlled. As with all chemical treatments, use pyrethrum spray in a targeted way and only when necessary. Unfortunately, the spray will also kill many beneficial insects, so only spray directly onto areas of infestation rather than using it as a routine preventative measure. You may also like to cover treated plants with netting to help keep bees, ladybirds, and other allies away until the poison breaks down after a few days of direct sunlight. No gardener wants to use chemical treatments unnecessarily, but sometimes there’s no other realistic choice. If you need an insecticide that’s purely organic and free from lasting environmental effects, there are few better options than a homemade pyrethrum spray. Download Article Download Article Most gardeners are aware of the effectiveness of pyrethrum in killing pest insects. Pyrethrum spray is made from the heads of Chrysanthemum cinerariaefolium or Chrysanthemum roseum. This mixture will be effective against most insects in the garden.
- 1 tablespoon flower heads of either Chrysanthemum cinerariaefolium or Chrysanthemum roseum.
- 1 liter (0.3 US gal) / 33fl.oz hot water
- Pinch of soap powder
- 1 Obtain the flower heads.
- 2 Mix the flower heads with the hot water. Allow to stand for one hour. Advertisement
- 3 Strain off the flower heads.
- 4 Add the soap powder and mix.
- 5 Pour the mixture into a spray bottle.
- 6 Spray.
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- QuestionWhere can I buy chrysanthemum liquid?It’s available as an essential oil for aromatherapy, but I doubt that would work as an insecticide. If you’re going to buy liquids, you might as well go store-bought and buy a pyrythrin-based insecticide. Sprays made to knock down and kill wasps are mostly pyrythrin. The stuff
- QuestionWhat soap powder do I use with pyrethrum water mix?Care should be taken not to mix pyrethrum with lime, sulphur, or soap solutions, since pyrethrum is broken down by both acid and alkaline conditions.
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- Chrysanthemums are often found in the gardens of flower enthusiasts. If you aren’t growing your own, ask around.As a small thank you, we’d like to offer you a $30 gift card (valid at GoNift.com). Use it to try out great new products and services nationwide without paying full price—wine, food delivery, clothing and more. Enjoy!
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- Spray with care — this will also impact beneficial insects.As a small thank you, we’d like to offer you a $30 gift card (valid at GoNift.com). Use it to try out great new products and services nationwide without paying full price—wine, food delivery, clothing and more. Enjoy!
- This is a controversial pesticide. Many web sites say it is harmless to humans and mammals and that it degrades quickly, but some studies indicate that it is very harmful to humans, dogs, cats, and that it lingers in dust. See Cox, Caroline, 2002, Insecticide Factsheet Pyrethrins/Pyrethrum, Journal of Pesticide Reform, Vol. 22, No. 1, 14–20.As a small thank you, we’d like to offer you a $30 gift card (valid at GoNift.com). Use it to try out great new products and services nationwide without paying full price—wine, food delivery, clothing and more. Enjoy!
Things You’ll Need
- Spray bottle
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|How to make your own organic pyrethrum insecticide|
You may be familiar with the word ‘Pyrethrum’ from the packaging of many ready-to-use organic insect sprays. However it was once one of the most popular insecticides available until the introduction of modern synthetic insecticides. This insecticidal chemical is derived from the dried, powdered flowers of the pyrethrum daisy, Tanacetum cinerariifolium and has been used as early as 1880 as a treatment to control mosquitoes. The active ingredients ‘Pyrethrins’ are mainly concentrated in the seeds of the flower head, and work by way of a contact insecticide. This means that the insect only has to be touched by the active ingredient to be affected.
Pyrethrins have a quick knock-down effect on insects, working in some ways like a nerve toxin. With the right dosage insects can be paralysed in mid-flight, but if the dose is too low they will just be knocked out and fly off later on once they’ve recovered. On food crops pyrethrins can be applied up to one day before harvest because they are quickly destroyed by light and heat. This means that they are not persistent in the environment and this is why pyrethrins have their ‘organic’ label. Be careful though as Pyrethrins will kill ladybirds, aquatic insects and the predators that eat them although they do not appear to be harmful to bees. HOW TO MAKE YOUR PYRETHRUM INSECTICIDE
|How to make your own organic pyrethrum insecticide|
Pyrethrum daisies are easy to grow in the English garden and are readily available at most good plant retailers. That way — if you have pyrethrum in the garden — you will have the main ingredient conveniently close by when you are ready to make your spray. The importance of this becomes clear when you realise how quickly the active ingredient within the pyrethrum flower will degrade..
The concentration of pyrethrin is at its peak when the flowers are in full bloom, this is recognised as the time when the first row of florets on the central disk opens — up until the time that all the florets are open. Pick the flowers in full bloom and then hang them in a dark sheltered spot to dry. Traditionally, in Japan, the flowers were harvested with their stems intact, and hung upside down in water for between 24 to 48 hours before drying. The reason for this process is that it can increases the pyrethrin levels. Once dry, crush the flowers into a powder using a mortar and pestle or a blender. The finer the powder is the more effective it will be against insects, but it will deteriorate more rapidly. To apply as an insecticidal dust, simply apply the dried and crushed flowers on to the leaves of plants that require its protection. To use as a spray, soak ten grams of pyrethrum powder into three litres of warm water for three hours, after this it is ready to be sprayed. It is possible to use fresh flowers instead of dried but you will need to use up to four times the amount of plant material to get the same concentration of active ingredient. The efficiency of pyrethrum can be greatly improved with the addition of other products such as sesame seed oil or washing up liquid. These can be added at a dose of one teaspoon per litre of solution and can increase the effectiveness of your spray up to four times the norm.
As mentioned before pyrethrum breaks down quickly after application giving no more than 48 hours of protection (12 hours is generally nearer the mark) depending on the concentration of the mixture sprayed. One of the ways that this degradation can be slowed down is to add antioxidants such as tannic acid, a chemical found in the bark of several tree species. Even so it will be necessary to reapply after rain. You may need to experiment with the amount of water your powder is being added to as the concentration of pyrethrins in the dried flowers will be an unknown variable. If your spray does not seem to kill insects, try using use less water next time you make your spray. HOW TO USE YOUR PYRETHRUM INSECTICIDE: Pyrethrins are more effective at lower temperatures, so for best results, apply in early evening when temperatures are lower. Spray both the upper and lower surfaces of the leaves, because the active chemicals must directly contact the insects. Try to reach any which may be hiding between the leaf crevices. You should find that your first spray will often excite hiding insects and bring them out of their place of hiding. If so, a second dose of the right concentration should finish them off. Remember to never use pyrethrin sprays or powders around waterways or ponds. HOW TO STORE YOUR PYRETHRUM INSECTICIDE: Pyrethrins are notoriously unstable components which can quickly break down when exposed to light and heat. However the levels of pyrethrum concentrations can be maintained for up to six months by keeping the crushed flowers in a freezer. Alternatively you can try keeping your powder in a sealed container, and storing it in the fridge. This should also keep your prepared pyrethrum powder viable for at least a couple of months. REMEMBER: It is illegal to produce and use insecticides without being licensed by Her Majesty’s government. Main image credit — KENPEI https://creativecommons.org/licenses/by-sa/3.0/deed.en
In text image — By Roger Culos — Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=22714021
For related articles click onto the following links:
PYRETHRUM FLOWER SEEDS
HOW TO GROW ERIGERON KARVINSKIANUS
HOW TO MAKE A NATURAL AND ORGANIC INSECTICIDE SPRAY FOR APHIDS
ORGANIC CONTROL OF CATERPILLARS
Organic Pyrethrum Insecticide
Sacrificial Planting This article is part of ourOrganic Pest Control Series, which includes articles on attracting beneficial insects, controlling specific garden pests, and using organic pesticides.
What Is Pyrethrum?
One of the oldest pesticides known, pyrethrum is also the strongest insecticide allowed under National Organic Standards guidelines. Made from the dried flowers of a little white daisy now classified as Tanacetum cinerariifolium, pyrethrum insecticides are known for their fast knock-down of unwanted insects. Insects typically become paralyzed as soon as they come into contact with pyrethrum, so it’s often used in wasp sprays. Pyrethrum use in the garden should be undertaken with care and only after cultural methods that might manage a pest have been exhausted. Pyrethrum insecticides are highly toxic to bees, wasps and other beneficial insects, as well as to fish.
Which Pests Does Pyrethrum Control?
Aphids, armyworms, cucumber beetles, cutworms, squash bugs, whiteflies, leafhoppers, thrips and Colorado potato beetles are often brought under control with pyrethrum. Pests that cannot be reached with the spray — for example, corn earworms or leaf miners — should not be treated with pyrethrum products. Additionally, very challenging pests such as cucumber beetles and squash bugs are best managed by excluding them with row covers, with pyrethrum used as a late-season remedy should pests get out of control.
How to Use Pyrethrum
Pyrethrum degrades quickly in sunlight, but precautions still should be taken to protect beneficial insects from exposure. When using pyrethrum to control insects that take flight, such as cucumber beetles, apply pyrethrum early in the morning and then cover the treated plants with row cover or an old sheet to exclude bees and other beneficials for 24 hours. To put a damper on squash bug populations, spray plants as soon as the first nymphs are seen, and again one week later. Do not use pyrethrum in situations where lady beetles, honeybees and other beneficials are active. Used carelessly, pyrethrum can wipe out these and other beneficial insects. Home production of pyrethrum pesticides is practical for the resourceful homesteader. Native to current-day Yugoslavia, the Dalmation daisy is a cousin of feverfew, which it closely resembles. Hardy to Zone 6, the plants grow as short-lived perennials and often reseed in hospitable spots. If the dried flowers are soaked in warm water for three hours, the resulting spray is highly toxic to insects for about 12 hours. People who are allergic to other members of the Aster family may react badly to this daisy’s pollen. Purchased pyrethrum products require less handling and therefore may be safer to use. Look for the OMRI label when choosing a pyrethrum insecticide, because non-listed products often contain piperonyl butoxide, which is considered a possible human carcinogen. Organic pyrethrum products often contain oils or soaps to enhance their effectiveness.
How to Store Pyrethrum
Mix only as much concentrate or infusion as you will need. If not used within one day, place the container in the sun for a few hours and dispose of unused solution by pouring it out in the sun. Sunlight rapidly degrades pyrethrum, and the half-life of pyrethrum in soil is only one to two hours. Store pyrethrum products in their original containers on a high shelf, out of the reach of children and pets, in a dark place at cool room temperatures. Under good storage conditions, the shelf life of pyrethrum is about 1 year. Dried pyrethrum daisies can be stored in the freezer in an airtight container for at least six months. More information on pyrethrum is available from Cornell University. Pyrethrin-based insecticides are a class of organic insecticides derived from natural substances found in a single species of the Chyrsanthemum genus (C. cinerariifolium), also known as Dalmation daisy or pyrethrin daisy. Pyrethrin-based products are a very popular class of organic pesticides, since their nerve toxins are effective against many soft-bodied insects but have very low toxicity to humans and animals, including household pets such as cats and dogs. In fact, various shampoos that control head lice in humans and fleas in pets contain pyrethrins. Many manufacturers market pyrethrin pesticides, but in many cases, these are synthetic versions that have added chemicals. But it is also possible to make your own effective—and genuinely organic—pyrethrin insecticide if you happen to grow Dalmation daisies or have access to them.
What Is Pyrethrin?
The term «pyrethrin» refers to any of the six target plant molecules (esters) which are extracted from C. cinerariifolium to use as a natural organic pesticide. The combined extraction containing multiple pyrethrins is sometimes referred to as «pyrethrum.» Similar pesticides made by synthetic chemical processes, often including additives aimed at making the pesticide more long-lasting, are known as «pyrethroid» pesticides. But while pyrethrins are considered organic pesticides, pyrethroids are not.
When to Make and Use Pyrethrin Insecticide
When genuine organic pyrethrin pesticides are commercially available, it may be best to opt for those products, since they have been refined under careful control and will produce predictable results. But in some cases, the pesticides available for sale may be pyrethroids, which are NOT organic. So if a true organic pesticide is your goal, then making your own pyrethrin pesticide may be the best option. As far as application goes, it’s best to regard any pesticide as a last resort, reaching for the spray only when plant damage becomes intolerable. Left alone, populations of garden pests often find their own equilibrium, as predatory insects respond to the appearance of aphids or other damaging insects. But when a particular plant is suffering damage you can’t tolerate, then an organic plant-based pesticide such as pyrethrin or neem oil is always a better choice than a synthetic chemical pesticide. Pyrethrin insecticides are effective against a wide variety of insects, including soft-bodied chewing and sucking insects such as aphids, leafhoppers, mealybugs, spider mites, stink bugs, scale, thrips, and whiteflies.
Just because it is organic doesn’t mean that a pyrethrin-based pesticide is utterly safe for all living creatures. In fact, pyrethrins are quite toxic to fish and various other forms of aquatic life, so you should never use them around ponds or bog gardens, especially where runoff might reach natural streams.
Pyrethrin insecticides are biodegradable and will break down within a few days in direct sunlight. The insecticide does not persist in the soil or on the crop, which is why it is relatively safe to use within a vegetable garden. Remember that pyrethrin is highly toxic to most insects. While it is an effective agent against pests, it can also be deadly to the beneficial insects that pollinate your garden and eat pests. It is not wise to broadcast-spray pyrethrum on all your plants. Use the insecticide as a spot treatment only when and where you have a pest outbreak. Pure pyrethrins have low toxicity to humans and pets, but they are not entirely harmless. Some people have skin sensitivity to these compounds, and oral consumption can lead to digestive distress. You should use proper caution when mixing and using pyrethrin pesticides, as just because they are organic does not mean they are utterly harmless.
Before Getting Started
Making your own pyrethrin-based insecticide can be done using ingredients you probably already have on hand around your home, as well as a few inexpensive extra items. You will also need a garden that has some actively growing Chyrsanthemum cinerariifolium plants. Not just any daisy will do, as only C. cinerariifolium contains the pyrethrins that make for an effective homemade pesticide. In the garden trade, this plant is usually marketed as Dalmation daisy or pyrethrin daisy, and it may be sold according to its previous botanical name, Tanacetum cinerariifolium. Dalmation daisy is a popular garden plant for cottage gardens or for naturalized wildflower gardens in locations with relatively dry soil. These perennial daisies are hardy in USDA zones 4 to 10, so it’s generally possible to find them at most garden centers, especially those that specialize in wildflower selections. If you don’t have your own growing plants, it’s also possible to buy cut flowers from a floral shop, as the Dalmatian daisy is a popular cut flower.
- Dalmation daisy flowers
- Liquid dish soap
- Cooking oil
Gather and Dry the Flower Heads
During their active bloom season (early and mid-summer) harvests some fully opened flowers of your Dalmation daisies. You need not worry about over-harvesting, as vigorous cutting only prompts additional flowering on these plants. But an effective amount of pesticide can be created with as few as 12 flower heads. Place the harvested flower heads in a paper bag and hang them in a cool, dry, dark place to fully dry. This can take a few weeks.
Store the Flower Heads
Transfer the dried flower heads to a tightly sealed, airtight container and place in a freezer. They will retain their effectiveness for up to six months if frozen. Do not pulverize the flowers until you are ready to mix the pesticide.
Make the Solution
When you are ready to use the pyrethrin pesticide, wear a protective mask and use a mortar and pestle or coffee grinder to pulverize enough flower heads to make 1 cup of fine powder. It is crucial that the powder be quite fine in order to enhance the extraction of the pyrethrins. Add the finely ground powder to a quart of warm water and let the solution soak for three hours, stirring occasionally.
It is also possible to use the pulverized powder as pesticide dust without mixing it with water. This can be an effective method for certain plants that don’t react well to wet leaves, such as roses. A powder is also effective for applying over the soil. Pyrethrin powder also has the advantage of being storable for a longer period.
Strain the Solution
The raw solution will often clog a sprayer, so the next step is to strain it through cheesecloth to separate the pyrethrin-enhanced liquid from the pulverized flower parts. Next, mix the strained liquid with a teaspoon of liquid soap and a teaspoon of cooking oil to enhance its ability to cling to plants. Mix thoroughly, then pour the solution into a clean spray bottle for application.
Homemade pyrethrin pesticide has a shelf life of only 12 to 24 hours, so any that is leftover after application will need to be discarded. Thus, it’s best to grind and mix the pesticide in relatively small amounts as you need it.
Apply the Pesticide
Use the solution as you would any commercial spray insecticide. The strength of homegrown pyrethrin varies, so feel free to experiment with the proportions until you achieve effective insect control. Make sure to prevent pyrethrin sprays or powders from running off into ponds or water supplies, as pyrethrins are toxic to many forms of aquatic life.
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