How to prepare pyrethrum in a natural way
Pyrethrum is an insecticide of plant origin extracted from the flowers of some composites, including the Pyrethrum of Dalmatia (Tanacetum cinerariifolium (Trevir.) Sch.Bip.). It is actually a mixture of compounds (esters of chrysanthemic acid and pyrethrum). The insecticide action is carried out through mechanisms that interfere with the central nervous system of insects, with action on the ganglia and on the synapses.
In order to obtain this natural insecticide, it is necessary to start from the cultivation of the Dalmatian Pyrethrum and for the extraction of the active ingredients the flowers are picked manually in full bloom, when the content of pyrethrins reaches its peak. The pyrethrum produces large quantities of flowers which, once collected, are crushed or ground to obtain a greenish-yellow powder, called “raid”, very thin and then diluted in water: for the doses the recommended proportions must be a spoonful of pyrethrum powder in a liter of water.
This mixture should be shaken well before use and then sprayed on the plants (the one that remains should be stored in a dark place). The pyrethrins having a low light stability, should be sprayed on the plants in the late afternoon hours, when the sun goes down.
But the plants from which pyrethrum is extracted can be used directly in our cultivated fields as repellents for fruit and vegetable insects. Just arrange hedges of these chrysanthemums at a regular distance from the crops. The acrid odor emanating from cultivated pyrethrum acts as a repellent against harmful insects. In this way we should not distribute the insecticide derivative that, although it is of natural extraction, is always a product with its toxicity as well as for humans and animals also for pollinating insects (bee in the head). In the case in which instead the pyrethrum is used as an insecticide on fruits and vegetables let’s remember to consume them not before having spent at least 3-4 days. Once collected, they must be thoroughly washed, allowing the elimination of this natural insecticide which, not being systemic (ie it does not penetrate into the tissues), can be eliminated.
The mechanism of action of pyrethrum, not being selective only for insects, obviously has consequences also on humans and animals; for this reason it should not be used superficially and distributed in moments that are not windy, with masks, goggles and adequate respiration and skin protection.