The availability and use of chemicals in gardening is coming under more and more scrutiny in recent years. While organic gardening was a popular trend in previous years, this trend as begun to develop in to a more conservation focused method of gardening. Many commonly used garden chemicals are slowly being removed from shelves as they have been proven to be unsafe for use in crops & harmful to our soils.
While some chemicals are getting a bad reputation, others are coming into their own. One such product is the ancient and naturally occurring Pyrethrum. This insecticide has been around for many years, but only in recent days has its popularity and benefits been brought into focus.
Pyrethrum comes for a Daisy plant called Chrysanthemum cinerariaefolium which is grown in Africa. We too can grow the Chrysanthemum flower here in Ireland. If you collect the seeds of this plant you may be able to make your own insecticide at home.
For many years & in ancient times the naturally occurring oils of the plant’s seeds have been used as an insect repellent. It has been used to repel mosquitoes in Africa and it was used to delouse during the world war.
Nowadays the daisy of Pyrethrum is grown in 10 countries where the seeds are collected and then refined to make a safe insecticide oil. This product is available to gardeners to protect their crops from pests.
The insecticide is considered safe for use on crops and will breakdown quickly in sunlight meaning that it has no long term effects on our soil or the environment and it will not show up in our foods.
Pyrethrum will only affect flying & crawling insects. When applied in large quantities it acts on the central nervous system of insect, leading to the death of the insects. In smaller doses, pyrethrum acts as a deterrent or repellent. At low doses the chemical causes insects to act differently and in ways makes the pests less harmful.
Among the list of insects that pyrethrum controls are:
Aphids, blackfly, greenfly, whitefly, Thrips, caterpillars, Root flies, carrot fly, cabbage root fly, Spider mites, as well as more.
In terms of toxicity to bees, pyrethrum is slightly toxic to bees. It is act level 3 toxicity – meaning that pyrethrum is moderately toxic to bees and can kill them. To ensure minimal harm to bee populations it is important to keep to the recommended dilution rate listed on the bottle. For Pyrethrum 5EC a dilution rate of 20ml per 5 litres of water is recommended. Also, apply the insecticides late in the evenings or early in the morning – as bees are less active at this time of day. Lastly, when dew is forecast, avoid apply pyrethrum as its toxicity to bees increases in these conditions.