When we speak of insecticides in the framework of organic crops, we refer to natural substances or preparations of natural elements, which produce certain repellent effects or death in insects. In reality, they act more as physiological disturbances than as insecticides in themselves, compared to the classical chlorinated or phosphorous organs. These substances, prepared at home, produce a certain population alteration that helps to keep pests at tolerable levels. In this way, an abrupt decrease of an element of the system is avoided, which can produce an ecological imbalance and bring serious consequences, as it happens with the use of the classic insecticides.
There are plants that have a strong repellent or insecticide power, science knows more than 1500 species that can be used for this purpose. An example is a chrysanthemum, from which pyrethrins are extracted.
A control program begins with the association of strategic plants and, later, if the populations are increased according to a follow-up by means of a correct sampling, the homemade preparation of solutions or products that have counterproductive effects for some plagues will be resorted to.
Fermented slurry: plant parts are enclosed in permeable bags and placed in a container with rainwater. The container is covered but allowing the air to circulate, it is stirred every day until a change of color is noticed. This happens in a week or two. Its smell is very unpleasant, so you can add a few drops of chamomile flower extract or a few drops of valerian. It is applied diluted, especially if it is done on the foliage, the recommended dilution is 1 in 10 parts.
The slurry in fermentation: the plants are submerged in rainwater and left in the sun for 4 days.
Infusion: the fresh or dried plants are placed in boiling water for 24 hours.
Decoction: soak the plant materials for 24 hours, then boil them for 20 minutes, cover and let cool.
Maceration: place fresh or dried vegetables in water for no more than 3 days. Care must be taken that it does not ferment, and then the supernatant is used. Infusion: Cover the vegetable with hot or boiling water and let it cool in a container with a lid.
Flower extract: fresh flowers are used as much as possible, freshly opened, cut, moistened and “pasted” with the help of a mixer. The liquid is extracted from them and can be kept in a bottle with a screw cap. Use diluted.
Collection and drying of the material: vigorous plants should be chosen, to dry them spread them on papers and place them in a warm and aerated place at less than 30 degrees. The treatments of infusions or decoctions should not be used, in general, during rainy days, cloudy or of great insolation.
Alcoholic extract: The vegetable is covered with alcohol and left to macerate.