Leaf diseases are considered one of the main factors that limit the exploitation of the maximum productive potential of a crop. When an effective control method is not implemented and environmental conditions are not specially developed, diseases, such as fungal diseases, can cause losses of up to 100% in grain productivity.
There are several strategies, which combined, eliminated or abandoned diseases caused by fungi. However, chemical control is one of the most used and efficient methods, proving to be an economically viable practice. The number of applications will depend on environmental conditions, the presence of the pathogen during the crop cycle and the susceptibility of the variety.
Some factors are essential to carry out a fungicide application properly, in addition to being carried out at the correct time, it is necessary to provide sufficient coverage of the target and deposit the necessary amount of defense on it, avoiding minimum losses and contamination of the environment. For this, the addition of adjuvant to the combustion mixture, both aerial and ground, plays an important role in the efficiency of fungicides.
Fungicide applications are generally carried out when plants have a higher leaf area index, making it difficult for the pesticide to penetrate, especially in the lower part. If there is no necessary coverage, control becomes inefficient, even in applications with systemic products. These products generally have limited movement in plants and also require good distribution throughout the canopy. Furthermore, some fungicides move from the base to the top of each leaflet or leaf, with minimal chance of movement in the opposite direction and without the possibility of translocation from one leaf to another.
Coverage
To improve coverage on a plant surface during fungicide applications, some strategies can be adopted, such as:
To improve coverage on a plant surface during fungicide applications, you can adopt some strategies, such as:
Increase the application rate: applying a greater volume of syrup can result in more uniform coverage of the plants, ensuring that the products reach all areas of the crop. However, it results in lower operational performance, in addition to favoring drop monitoring.
Reduction in droplet diameter: thinner droplets in thickness, detect better coverage in the lower third of the plants due to their ability to penetrate the canopy. However, smaller droplets are more likely to be carried by the wind, which can result in product losses due to drift.
Spreading: the spreading of the drops allows them to cover a larger area of the leaf surface. But, superspreading increases the risk of early evaporation of the droplet, especially in conditions of high temperature, low relative humidity and wind.
Adjuvants: the addition of an adjuvant to the fluorescence mixture is essential to improve the coverage and effectiveness of the application of phytosanitary products. In the current market, we find adjuvants that have high-performance anti-evaporants in their formulation. These products guarantee the protection of the droplet along the tip-to-target path, preventing the loss of very fine droplets, which reduces their drift and premature extinction and, thus, , reduces evaporation.
Furthermore, using the right adjuvant is capable of reducing surface tension without causing super-spreading. This results in a reduction in the contact angle of the drops on the leaf surface, allowing the drops to cover a larger area, while also favoring the absorption of the fungicide.
