How to ensure efficient and safe application in coffee cultivation

Phytosanitary management in perennial crops, such as coffee, is practiced repeatedly throughout the year, even in challenging conditions to obtain a good quality application.

To be of quality, the application must bring together four fundamental aspects: 1) protect the crop, after all, this is the objective for which it is being carried out; 2) be safe for the applicator performing the application; in this case, the use of Personal Protective Equipment (PPE), from the beginning of the preparation of the mixture to the decontamination of the sprayer and its components, is the main ally, together with systematic training on application technology; 3) protection of the environment, so that there is no contamination of soil, water, pollinators, among others, and entry into the trophic chain; and 4) consumer protection, as recommended doses, products registered for the crop, grace periods are used, among other good practices that are basic premises of the technology for applying phytosanitary products.

Once these four aspects are met, it is possible to state that the use of phytosanitary products in agriculture is safe for all entities in the chain, such as producers, consumers and the environment.

There is a generic understanding, the origin of which is difficult to pinpoint, that fine drops should be used to apply fungicides; medium drops for insecticides and some herbicides; and coarse drops for herbicides. It is not a technical recommendation, however, existing in the environment of users of technology for applying phytosanitary products, but which does not find support and support in scientific research.

The selection of droplet size must be a planning task for each application, as it cannot be generalized, as it is linked to several intrinsic factors at each moment of spraying. For example, summer/winter, instantaneous psychrometric conditions in which you want to reach a certain target, level of infestation or incidence, canopy volume and number of leaves to be covered with drops. However, recommendations are often made in tables or on product leaflets, which generally happens without prior knowledge of the specific conditions under which the application will take place.

Simultaneously with the droplet size to be selected, parameters such as droplet density, percentage of coverage, relative amplitude, leaf deposition or retention, among others, must be analyzed. These act as a counter to the question: have we selected the right tip to produce the desired/recommended droplet size? It is essential to simultaneously analyze these parameters with the droplet size, as if considered in isolation it represents little information, as it is an absolute value represented by the Volumetric Median Diameter (DMV). 

PULVERIZADORES

Applications with hydropneumatic sprayers or turbo atomizers in the Cerrado Mineiro coffee producing region are mostly carried out using tips that generate fine drops and, traditionally, when the producer replaces the tips, he opts for the same model. The issue is not the quality of the tips, but the fact that there is rarely a spare set that produces drops of different sizes on the farm, always using the same models for insecticide, fungicide and foliar fertilizer applications throughout the year, regardless of psychrometric conditions, spray volume, target, products, etc.

Knowledge in technology for the application of phytosanitary products recommends that conditions are dynamic and that the technician responsible must pay attention to the factors that affect the application, seeking to adapt, practically in real time, to changes in weather, the target, the crop, etc. ., to obtain efficient spraying and effective control of agents harmful to crops.

Sprayers and the technology available for phytosanitary management in coffee farming are significantly outdated compared to hydraulic boom sprayers. These include on-board weather stations, automatic closing, covers with more than one tip to facilitate droplet size replacement, efficient control of working pressure, among other technological advances that have not yet been added to sprayers used for phytosanitary management in coffee farming. According to some manufacturers, the technology is available, but there is no demand from farmers or willingness to invest a little more in the equipment. Would there be an explanation for this fact?

On coffee producing farms, it is common for the team to calibrate the sprayer by measuring the flow rate from one to three points on each bar. Would this sampling be sufficient to give a perception of the uniformity of distribution of the syrup in the plant canopy? Meanwhile, the operator “takes a shower” if he chooses to measure at all ends. A more economical alternative to joint tip evaluation systems would be a quick coupling system at the top, allowing the bar to be positioned horizontally when determining the flow, thus allowing operators to sample the flow of a greater number of tips or, perhaps, all, and would be more assertive in relation to the volume of syrup they are applying.

ALTERNATIVES

In the desire to present an alternative that meets the four fundamental aspects of the technology for applying phytosanitary products, namely, protection of the crop, applicator, environment and consumers, some work has been conducted by the Agricultural Mechanization Research Group (Grima) , made up of researchers from different Brazilian teaching, research and extension institutions, in different laboratories in the area of ​​application technology and agricultural mechanization.

The objective is to present coffee growers with research results that demonstrate biological efficacy, selecting drops appropriate to the moment, target, syrup volume and plant size.

An example of these efforts is summarized below, where research work was conducted with the following application conditions: tip “A”, fine drops, and tip “B”, thick drops, according to the classification of the American Society of Agriculture, Biology and Engineering (Asabe) S 572.1. Both produce an empty conical jet at an angle of 80º, spray volume of 200L/ha and 400L/ha, working speed of 3,8km/h to 7,8km/h, working pressure of 565kPa to 1.241kPa, average meteorological conditions of 29°C temperature, 37% relative humidity and 4,3km/h wind speed, aiming to control the coffee leaf miner.

This insect presents a peak in infestation that coincides with a period of low relative humidity and has been one of the biggest problems in coffee farming. The application carried out proved to be safe from different aspects and protected the crop, presenting partial results of the work and with significant effects (Tables 1, 2, 3 and 4). This application occurred in an area with an infestation of 65% of live larvae; therefore, in very critical conditions.

The volume of 400L/ha is usual on properties in the region and as an alternative, 200L/ha showed greater effectiveness with thick drops, compared to what is traditionally used. A general analysis of the parameters presented allows us to infer that the use of thick drops can be a viable alternative for the coffee grower, combined with a smaller syrup volume.

The same tips and volumes of syrup were used in a study to control the coffee borer, and the results indicated similar behavior in terms of application parameters and control effectiveness, with greater deposition of tracer dye in the fruits when using the “B” tip, which produces thick drops.

EVALUATION

Decision-making regarding the size of the droplet to be used requires extensive knowledge about the target, environment, machine, plant architecture, among others. The need for systematic and continuous training of field teams is essential to conduct safe applications in all aspects, and it is necessary for the producer/entrepreneur to understand this reality so as not to increase society's animosity towards agricultural activity and the use of products essential phytosanitary products for crops. It is clear that most Brazilian producers are cautious and aware of their social responsibilities. However, it has not been enough to keep the concerns and care taken from the front door inside to oneself, it will be necessary to demonstrate to society that its actions will reflect waste-free food produced in a technical way on the consumer's table in their homes, in urban centers.

Finally, phytosanitary product spraying operations have been criticized by society and, in some cases, it is possible to affirm that there is reason and basis for the criticism. The solution to harmonization between consumers and producers is the correct use of application technology, which consists of the science of applying phytosanitary products at the correct time and place, with minimal waste, as well described by Professor Tomomassa Matuo.

Cleyton Batista de Alvarenga,
Paula Cristina Natalino Rinaldi,
João Paulo Arantes Rodrigues da Cunha,
Renan Zampiroli,
Matheus Vilhena Parenti,
Dalton Luiz Benz,
Marcos Paulo Resende Ribeiro and
Darlisson Medeiros Santos,
Agronome Paul Saint-Paul
Túlio Urban Lourenço Miranda Silva,
Federal University of Uberlândia