Pesticides are chemicals that may be used to kill fungus, bacteria, insects, plant disease, etc. These chemicals work by ingestion or touch and death may occur immediately or over a long period of time.
An insecticide is used to specifically target and kill insects.
Pyrethrum is an insecticide allowed in organic farming , as its active ingredient is of completely natural origin. The pyrethrin in fact is obtained from a flower.
It can be very useful in the vegetable garden and in the orchard for its effective killing action on many parasitic insects, as well as in the garden to defend against mosquitoes. However, you have to be very careful when using it . The fact that it is natural does not mean that it can be used without any precaution: it is still a product with its own toxicity. Pyrethrum can kill beneficial insects , such as bees and ladybirds, in addition to harmful insects in the garden .
It is therefore useful to know something more about this biological insecticide treatment, to understand in which cases it may be worthwhile to use it and when instead it is better to fall back on systems with less ecological impact.
Chrysanthemum cinerariifolium
This insecticide is obtained from the African plant Chrysanthemum cinerariifolium of the composite family , from which pyretine , which is the active ingredient of the insecticide, is extracted .
The flowers of the natural pyrethrum , cultivated since ancient times, look like daisies and dry and grind to obtain a powder to be diluted and sprayed on the plants to fight parasites and insects.
Pyrethrum powder would therefore be a totally natural substance. Unfortunately today the pyrethrum-based insecticides found on the market are almost never truly “natural” products, but are the result of the work of chemical laboratories. Although distant from the original pyrethrin, pyrethrum insecticides are in any case to be preferred over other pesticides, because the starting point remains of natural origin and are allowed in organic cultivation. There are also insecticides made with synthetic pyrethroids, these are not allowed in the organic.
For those who want to create a truly eco-sustainable garden, unable to obtain the chrysanthemum to grind or from which to obtain a natural extract, it is better to first resort to even less toxic organic insecticides such as neem oil , or self-produced solutions, such as the nettle macerate .
Everything you need to know about the insecticidal action of pyrethrum can be summarised in points:
- Quickly kills insects . Pyrethrum extract works by blocking the insect’s nervous system.
- It is not selective , it acts on a broad spectrum, affecting a very wide range of insects. If we want to look at the bright side of this is that we can use it against almost any insect pest in the garden, from fruit fly to mosquito. The downside, however, not to be underestimated, is that it also kills bees , ladybugs and many other beneficial insects. For example, it can exterminate pollinating insects that are involved in pollinating fruit trees and horticultural plants. So you have to use it only without fail, trying to use it only if strictly necessary.
- It acts by contact , ie kills if it hits the target, it is not translaminar (ie it is not able to penetrate plant tissues). The consequence is that if the insects are hidden among the leaves, for example among the thousand folds of a head of cabbage, they can escape the treatment. Generally at least two treatments are carried out for this very reason.
- It is not a systemic treatment , i.e. it does not enter the plant fluids and is washed away over time. The molecule degrades fairly quickly.
- It also has a repellent action . Discourage pests from visiting plants where pyrethrin residues remain.
Pyrethrum is a not very persistent substance , a characteristic that can reduce its lethal action but which is also a great advantage if used in the vegetable garden or in the garden, since the poison of the substance degrades rapidly.
When treating vegetables this is particularly important: the treatment has a short waiting period and therefore the insecticide can be used even shortly before harvest. In the garden, on the other hand, the advantage of its rapid decay is that it does not leave toxic residues that could annoy pets, children and even adults who live in the green space, which is why it is often used as an anti mosquito insecticide.
Pyrethrum degrades in particular when exposed to heat and sun, its effect vanishes. These characteristics combined with the low toxicity towards warm-blooded animals make it a little harmful and natural treatment, which we can use on the garden even in the organic method. After two or three days it will be possible to eat the treated vegetables.
However, you must be very careful: it is recommended that you read all the warnings on the package and scrupulously respect them . Each insecticide is a poison: whoever does the treatment must use suitable gloves and a mask, avoid ingesting or inhaling substance, as well as avoiding any contact with the skin.
In order not to damage useful insects, in particular bees, it is imperative to avoid treatments during the flowering of plants . Attention should be paid to waterways because pyrethrum is very harmful to fish and reptiles. In general (I repeat myself because it is an important concept) it must be taken into account that by using pyrethrum a poison is distributed in the environment, which it would always be better to avoid.
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