Agrochemicals are products intended for use in the production, processing and storage of agricultural products.
In most crops, the main agrochemicals used are insecticides, herbicides and fungicides however, the producer must take care to use only the agrochemicals sanctioned by the regulating authority, according to the legislation in force in his country and only use them under the guidance and recommendation of an agronomist.
According to the world convention for the use of agrochemicals, these are classified by toxicological class both for humans, as well as the ecological impacts they may cause to the environment.
The label of agrochemicals is the main form of communication between the manufacturer and the user, so it is important to read correctly all the information contained in the labels of the agrochemicals packaging.
All agrochemicals must be labeled with a label indicating their toxicological class.
The effectiveness of agrochemicals in controlling pests, diseases and weeds depends very much on their correct application.
The misuse of agrochemicals, in addition to jeopardizing their effectiveness, can contaminate
people and the environment, so it is important to carefully read the packaging label of agrochemicals and follow the agronomist’s guidelines.
1. DEFENSIVE APPLICATION TECHNOLOGY
The application technology is not limited to the application of the product, but rather to the interaction between several factors (crop, pest, disease, invasive plant, product, equipment and environment), seeking efficient control with low cost and minimal environmental contamination.
Main errors in the application of pesticides:
· Inappropriate product use;
· Deregulated equipment;
· Incorrect dose (sub and overdose);
· Moment of incorrect application (plant development phase);
· Application under unsuitable weather conditions;
· Water used to mix the pesticide in the tank is of poor quality (excess of suspended particles, PH incompatible with products, among others);
· Stops/Blockage with connected equipment;
· Draining and dripping;
· Excessive area overlaps during application.
2. ENVIRONMENTAL CONDITIONS AT THE TIME OF APPLICATION:
Climate conditions should be favorable to the absorption and translocation of products. In general, the climate conditions at the time of application should be as follows:
· The minimum temperature of 10°C — The ideal of 20–30°C, and the maximum of 35°C.
· Minimum air humidity of 60% — Ideal from 70 to 90%, And the maximum, 95%.
· Do not carry out applications in the presence of winds with speeds below 5 km/h or above 10 km/h, on stressed plants and in the case of imminent rainfall, otherwise the treatment efficiency will be lost or crops will be damaged.
In order to know if the wind is too strong to make an application, it is possible to make a very simple and practical test, in which a sheet of paper is placed on the floor, if it moves by the force of the wind, therefore changing its position is a Sign that the wind is too strong to carry out the application of agrochemicals.
Application to stressed plants reduces the absorption and translocation of the product and can reduce the metabolism of the molecules by the crop, reducing the selectivity in the case of the herbicides.
The occurrence of rain soon after the application can wash the molecules of the product off the surface of the leaf of the plant and prevent its absorption.
Some herbicides require up to six hours of rainfall after application to be absorbed in sufficient quantity to be efficient.
The low relative humidity causes dehydration of the cuticle and the consequent rapid evaporation of the drop on the surface of the leave, causing crystallization of the product on it, thus hindering the absorption of the molecule.
High temperatures can cause volatilization of the molecules and increase the evaporation of the droplets. On the other hand, low temperatures can reduce plant metabolism and hinder absorption.
Application in the presence of wind at speeds above 10 km/h may cause drift and droplets will not reach the target and may reach sites with sensitive cultures. The drift consists of the movement of drops or steam to non-target locations, causing damage to nearby crops. The main factors that affect drift are:
· Droplet size
· Height or distance between target and nozzle,
· Wind speed,
· Speed of application,
· Method of application, and
· Product volatility.
It is common, for example, to observe toxicity of certain formulations (2,4-D Ester) affecting neighboring areas, especially when this herbicide is applied under inadequate conditions.
The ways to reduce drift are:
· Apply at appropriate times
· Apply during the right environmental conditions stated earlier above
· Use appropriate formulations;
· Proper calibration of spray nozzles, and
· Use proper operating pressure.
One factor that the farmer must always consider is to respect the period of time between the last application of agrochemicals and the harvest, determined on the label of Agrochemical packaging.