Soybean rust outbreaks increase 220% in Brazil

One of the diseases that most worries soybean producers, and which arrives with a vengeance in this 22/23 harvest, is Asian rust. According to the anti-rust consortium, the first spores occurred in November 2022 in Rio Grande do Sul, in voluntary soybean areas, in the cities of Pântano Grande and Passo Fundo. Today, in total, there are forty-eight (48) occurrences and, for the most part, the crop is in the R5 stage, that is, grain filling.

Compared to the same period last year, November to January, the increase exceeds 220% between one season and another, with the State of Paraná having the most occurrences in this 22/23 harvest. According to experts from xarvio, BASF's digital agriculture brand, the main cause of this increase is the favorable, rainier and warmer climate.

Asian rust can occur at any stage of plant development. The first symptoms of the disease are small lesions on the leaf, brown to dark brown in color. Spores are released on the underside of the leaves, and the damage caused results in losses to grain formation and pod filling, with a reduction in the final weight of the grains, compromising the cultivation result.

As it is a very aggressive disease, constant monitoring and preventive applications of fungicides are the most recommended for efficient control. Integrated management, with high-performance fungicides, applied at the right time, and the use of digital tools help to effectively control the spread of the infestation.

According to experts, if Asian rust management is not carried out correctly, the disease can cause a reduction of up to 90% in soybean productivity. It is essential that the farmer is efficient in control, carrying out constant monitoring to inhibit the development of the disease, increase productivity rates and ensure the longevity of the business.

Monitoring and control

Monitoring through biomass maps is one of the alternatives that farmers can use to assess possible damages. “We use the biomass map based on satellite data to provide short-term feedback on the status and development of the crop. We were able to identify which areas present a biomass deficit, subsequently identifying the anomalies that are in the field”, explains Davi Köhntopp da Silva, agronomist and Digital Products researcher at xarvio.

“In addition to rust, we are currently diagnosing in crops through images captured by Xarvio the occurrence of many end-of-cycle diseases, which, as the name suggests, are normally expected to occur in the last reproductive stages of the soybean crop, and in this harvest are advanced. We have been monitoring diseases such as anthracnose, leaf blight, brown spot and frogeye spot. Due to the high temperatures and the rainy season, the climate is favoring the appearance of fungi at the beginning of the reproductive stage. The farmer needs to ensure phytosanitary monitoring and adequate management to increase the productivity and profitability of the crop”, says the agronomist.

Another point to be considered in the efficient management of diseases, both rust and DFC (End of Cycle Diseases), is the active ingredient contained in commercial products that will provide the best control. The successive use of fungicides containing the same mechanism of action can contribute to an increase in the population of resistant fungi, leading to a loss of product efficiency and consequent losses for the farmer.

“These meteorological conditions of rain and heat have required more intensive monitoring and more careful control on the part of the producer. The recommendation is to pay attention to the application technology, carry out preventive management, apply at the right time and use efficient fungicides with different mechanisms of action, associated with multisite fungicides for a better result”, reinforces Sérgio Zambon, Technical Manager of Market Development Brazil at BASF.

The BASF agronomist concludes with some recommendations for controlling diseases such as rust and DFC:

1. Choosing certified seeds: the farmer must be careful when choosing good quality seeds, as they are essential to achieve good results.

2. Consider escape factors whenever possible: sow whenever the weather is favorable. This practice favors the uniform development of plants, minimizes the incidence of diseases and the risk of replanting.

3. Application quality: use revised and maintained equipment, with tips in good condition, correct dosage and application rate appropriate to the stage of the culture, always following the manufacturer's recommendations.

4. Respect the product leaflet: follow the leaflet instructions inherent to each product, such as dosage, moment of application and interval between applications.

5. Use of protective fungicides: this group of products is very important in managing resistance and acts preventively, controlling the disease even before it penetrates the plant's plant tissues. Its use is recommended in association with fungicides with specific modes of action.

6. Understand the dynamics of each epidemic: always consult a qualified professional to extract the best results from each tool.

7. Monitoring: it is necessary to adopt a strategy of continuous monitoring of crops so that rural producers' decision-making becomes increasingly assertive.