Spraying crops is a method that guarantees protection to plants against threats, such as fungi, bacteria, insects and weeds, also acting in the replacement of foliar nutrients and other technologies currently available on the market. The spraying and application of agrochemicals is necessary to increase agricultural productivity, minimizing the impacts of factors that affect the development of crops of economic interest. Thus, for spraying to be efficient, application techniques are fundamental to determine management efficiency.
Thus, the products that will be used in an application are presented in concentrated forms, requiring their dilution in water, forming a syrup. In this way, the preparation of the syrup requires special care, such as: compatibility between products, mixing order, climate and water quality. This last item, water quality, is intrinsically linked to control efficiency, as its chemical-physical characteristics can compromise the efficiency of agrochemicals.
Water quality
When thinking about application efficiency, water is the main medium that will directly influence the application. This is because water, due to its characteristics, is used as the main solvent and dilution medium for chemical and/or biological products. Therefore, the preparation of the syrup must be carried out with water free of impurities and organic matter, which can cause the obstruction of vital components of the sprayers. In addition, it can potentiate, through chemical bonds, the inactivation of herbicides, since the molecules of these agrochemicals can bind to other substances present in the water.
The pH of the water should also be analyzed, as fungicides, insecticides and herbicides work best with slightly acidic pH, ranging from 4 to 6. Therefore, the water used in pesticide applications should not have dissolved cations and anions (hard water ), which may be reacting with the molecules of the agrochemicals and, thus, compromising their efficiency, as well as not having an alkaline pH. In a condition of hard water and alkaline pH, to circumvent this problem and minimize negative impacts, a chelator and a pH reducer can be used, always added to the spray tank before placing the products and never after.
Water hardness is caused by the presence of cations such as Ca 2+. Mg 2+, which can cause the complexation of part of the molecules of agrochemicals, such as herbicides, fungicides and insecticides. Thus, reducing their concentration, available to be absorbed by the target, as well as reducing the absorption speed process. Thus, it is important to carry out an analysis of the quality of the water that will be used for the applications.
water temperature
The practice of diluting active ingredients requires special care with regard to water quality, so that it does not interfere with the efficiency of the diluted product. With this in mind, water is known as a great solvent because, through its polar structure, it allows the creation of hydrogen bonds, and thus can dissolve different types of molecules.
Therefore, the ideal water temperature for most applications is around 15°C to 25°C. Temperatures below 15°C can make it difficult to dilute the mixture, which can cause clogging of the sprayer nozzles, which will result in uneven application in the crop. This can be circumvented by pre-diluting in a bucket of warm water. It is worth mentioning that each syrup preparation is unique, and therefore it is always necessary to be careful and carry out the preparation correctly, following the technical recommendations contained in the product leaflet, in order to achieve maximum efficiency.
Influence on application efficiency
In order to achieve maximum efficiency in handling any type of agrochemical, we need to avoid the factors that most interfere with the application, such as: climate, preparation of the mixture, application volume, quality and temperature of the water. These factors also directly influence the absorption of the product by the plants, which can reduce its efficiency with the need for reapplication and higher cost to the producer. The water temperature, one of the factors mentioned above, can compromise the dissolution of the chemical molecules of the active ingredients, reducing their efficiency in controlling the desired target in the crop. It is worth remembering that all these factors, with the exception of the climate, can be controlled, maximizing the efficiency of the applied products.
Conclusion
Therefore, it is necessary, at least, to carry out an annual analysis of the quality of the water being used in spraying, seeking to maximize crop yields through more efficient management of weeds, pests and diseases. Thus, water should receive increased attention, as it can change the efficiency of chemical products when diluted.
In addition to good quality, attention should be paid to the temperature as well, staying around 15°C to 25°C. Therefore, with the correct handling and following all the product's indications, it is possible to maximize the results of the application, in addition to avoiding product losses and inefficiency.
Text written by Eduarda Seger and Thaysla Vezaro Wiedemann, academics of the Agronomy course at the UFSM campus of Frederico Westphalen, members of the Tutorial Education Program (PET) Agrarian Sciences, accompanied by the tutor, Professor Dr. Claudir José Basso.
