Agricultural production in Brazil has been growing year by year. According to the National Supply Company (Conab), for the 2022/23 grain harvest, the estimate is for growth with record trends in relation to the cultivation area and production. This also makes us think about increasing the use of agricultural defensives. Therefore, with the recent rise in the prices of phytosanitary products, it is necessary to use a more efficient application technology to avoid losses due to inefficient application, with spray nozzles being extremely important components in the efficiency of an application.
The quality in an application of phytosanitary products is associated with climatic and cultural conditions, pests, diseases, weeds, products and the equipment used. It is increasingly necessary to seek the best possible performance in an application, in this sense the spray nozzles are considered primordial components of a sprayer, since they are responsible for determining the flow and the spectrum of drops, in addition to defining the shape of the emitted jet. .
After all, tip or spray nozzle?
Usually the term “spray nozzle” is used as a synonym for “spray tip”, however, they are different structures. The nozzle is the entire assembly composed of the tip, sieve, body and cover, which is fixed to the spray bar, on the other hand, the tip corresponds to the terminal portion of the nozzle, which is responsible for the formation of the drops.
How to choose the best spray tip?
Choosing the appropriate spray tip for the application and desired objective is very important, since for each application of a phytosanitary product, there is a purpose that must be sought in order to have greater control efficiency. increasingly assertive in the choice of nozzles for each type of application, because today the market offers several models such as: flat fan jet, double fan, full cone, empty cone, among others, each with its own functionality.
Fan tips with mixed droplet spectrum, produced between 2 and 4 bar pressure, are suitable for the application of systemic post-emergent herbicides, contact fungicides, contact insecticides and growth regulators. The full cone tip is specially developed for localized applications, proving to be effective when used in systemic post-emergence, fungicides and contact insecticides. The hollow cone tip is excellent for fungicide and insecticide applications, it can also be used with knapsack sprayers.
Applications of fungicides at the end of the soybean cycle, for example, are the most demanding in terms of application technology. This is due to the need for the drops to reach the lower third of the plant in a phenological stage in which it has a very high leaf index. At this stage, it is essential to have a tip that provides the droplet with good penetration and effective coverage of the target, using tips that provide fine droplets, which increase target coverage. This concern with the spray tip in fungicide application is due to the low mobility of fungicides applied to the aerial part of the plant, that is, the efficiency in fungicide application is to cover the target well, and this is only possible with a type of tip that has a higher proportion of fine drops compared to coarse.
In the case of pre-emergence herbicide application, the use of tips with very thick drops is the best option in order to obtain excellent performance and excellent drift control. For contact herbicide applications, where coverage needs to be greater, the use of thick to medium drops is recommended, in this way it is possible to have adequate coverage with reduced drift.
What is the relationship between pressure and droplet size?
It is essential to emphasize that, for the same tip, the size of the drops will decrease as the pressure increases (for example, any tip will produce larger drops at 2 bar pressure than at 4 bar), and that, for the same pressure and tip type, droplet size increases with tip opening diameter.
Application technology has been evolving more and more and over the years it has proved to be fundamental for a more assertive and efficient agriculture with regard to management and, consequently, more sustainable. Thinking about it, it is essential to have equipment that can carry out this spraying with quality and that delivers good results. Analyzing the high cost of the products to be used and the problems that can cause a wrong application, spraying currently does not allow room for errors. It is essential for the success of the application to have well-calibrated equipment with indicated tips for each spraying.
Finally, the aspects to be observed when choosing a spray nozzle in search of a good application are diverse and require care, but every effort is worth bearing in mind that the application is an important moment and that will often dictate the harvest result. In addition, it is worth remembering that the longevity of a spray tip defined by the manufacturer is carried out in the laboratory using pure water. We know that on a daily basis in a production unit, in addition to water, we have the addition of one or more products, adjuvants, micronutrients, among many others, which can change the viscosity of the liquid and reduce the useful life of the spikes. Therefore, the flow calibration must be done annually by technicians, to assess whether there is a need for replacement.
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By Filipe Belchor Barcelos and Lucas de Mattos, students of the Agronomy course at UFSM, Frederico Westphalen campus, members of the Tutorial Education Program (PET) Agricultural Sciences, under the guidance of professor Dr. Claudio Jose Basso.
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