The practice of spraying agricultural pesticides is essential to ensure good crop development, and consequently greater economic gain per area.

One of the most used products in spraying is herbicides, used to control weeds, which if not controlled can contribute to a loss of yield in soybeans of up to 65% (Embrapa).

The average cost of herbicides has increased year after year, mainly due to the loss of efficiency of some products in controlling weeds, associated with the resistance of plants to some molecules, particularly in Brazil for buva (Conyza bonariensis) e capim-amargoso (Digitaria insularis), resistant to the active ingredient glyphosate.

Consequently, there is a need to jointly use other herbicides with different active ingredients in order to control these same plants, as well as making use of sequential applications in scenarios that are more difficult to control.

A study carried out in 2017 by Embrapa demonstrated that there may be a 222% increase in weed control costs in cases of mixed infestations of resistant horseweed and bittergrass in soybean crops.

Therefore, spraying herbicides provided a huge opportunity to reduce production costs, since spraying is carried out over the entire area and weed infestation is unlikely to occur in 100% of the area. Thus, selective spraying emerged to avoid wasting pesticides.

Conceptually, Selective spraying is the act of spraying agricultural inputs only in the desired locations, and this can be done basically in two ways: prior mapping of weeds in the area to be applied, post-processing the acquired images and generating a prescription map; or through the use of sensors attached to the sprayer bars that have the ability to identify in real time the presence of weeds and at the same moment activate the spray jets, this method being much faster, as it is not necessary to perform a prior mapping.

What are the applications of selective spraying?

Selective spraying opens up a range of opportunities to reduce waste, and consequently reduce the cost of inputs and optimize resources.

– In pre-planting desiccation, spraying is carried out with localized applications, activating the spray jet on any type of plants, not applying the product to bare soil or straw.

– In post-emergency application of the crop, with sensors that have the ability to differentiate cultivated plants from invasive plants, spraying is carried out only on weeds, as it is not desired that a herbicide reaches the cultivated crop.

– Pre-harvest applications They are also frequently used in order to homogenize the areas before harvesting the grain. In this case, plants that have already been naturally defoliated or are already in the process of senescence do not receive a dose of product, or they receive a lower dose (minimum rate), and plants that still have very greenish leaves receive a full dose of product.

– Applications in post-harvest, used to control weeds after cultivated plants have been harvested, preventing growth of the weed seed bank during the off-season period.

What savings can the use of selective spraying technology provide?

Product savings with the use of selective spraying technology in a crop depend largely on the cost of the products applied, percentage of weeds, number of applications and doses used.

Considering only one application of herbicides for pre-planting desiccation, using the active ingredients glyphosate, clethodim and 2,4-D, with doses recommended in the leaflet, the average cost per hectare in conventional application is around R$250.00/ ha, according to a survey carried out by Eirene Solutions with data obtained from CONAB in 2023.

Taking into account a weed infestation of 10%, which provides a saving 90% of product, the cost per hectare with the use of selective spraying becomes R$25.00/ha. For an area of ​​1000 ha, for example, Product savings in this case can exceed R$250,000.00 in a single application.

What is the reference selective spraying equipment on the market today?

The system that currently has the largest share in the Brazilian selective spraying market is SaveFarm, an entirely Brazilian technology that enables all the applications described in the paragraphs above.

The innovative technology features sensors with optical cameras installed along the spray bar that identify the presence of weeds through artificial intelligence and communicate with PWM valves installed in each nozzle body, responsible for activating the spray jets only when necessary.