Occurrence of Asian rust in soybeans increases 331% in the 2018/2019 harvest

The anticipation of sowing, the climate favorable to the development of the fungus and the presence of voluntary soybeans (guaxa) in the off-season are the main reasons for the significant increase in cases of Asian rust in the country's soybean crops in the 2018/2019 harvest. The Antirust Consortium* has already recorded 69 occurrences this season, 331% more than in the same period of the 2017/2018 harvest.

Paraná leads the disease records this season with 37 occurrences, 311% more than in the previous cycle. The states that have also recorded the presence of Asian rust to date are: Rio Grande do Sul (13 cases), Santa Catarina (7 cases), São Paulo (6 cases), Minas Gerais (3 cases) and Mato Grosso do Sul ( 3 cases).

Asian rust is considered the main disease in soybean cultivation in Brazil. According to Embrapa, the losses caused range from 10% to 90% of production. Humid weather and mild temperatures favor the development of the fungus Phakopsora pachyrhizi which spreads easily by wind.

“Preventive management is indicated to delay the appearance of the fungus and reduce the symptoms of the disease in the plantation. There are products suitable for each phase of the crop and the development of the disease”, explains Helio Cabral, Soy Marketing Manager at Basf.

BASF has a complete portfolio for controlling Asian rust in soybeans. Ativum fungicide can be used preventively at the beginning of plant flowering (R1 to R3). Preventive applications improve phytosanitary control and can increase crop productivity.

When the first spores appear in the area, the fungus must be prevented from developing. At this stage, it is recommended to apply the fungicide Versatilis. The product is a systemic fungicide from the morpholine chemical group that acts as an essential tool for managing soybean rust resistance.

The initial symptoms of the disease are small, brown to dark brown leaf lesions. On the underside of the leaf, there are lesions that rupture and release the spores. Severely infected plants show early defoliation, which compromises the formation, filling of pods and the final weight of the grain. 

“In regions where cases of rust have been recorded, farmers must reinforce control to prevent the proliferation of the fungus. To enhance results, we recommend using Versatilis in association with multisite fungicides, such as Status or other products recommended for disease control, in addition to rotating with products with different modes of action to prevent fungus resistance”, warns Cabral. .

Correct management of Asian rust prevents productivity losses and allows for better profitability, contributing to the legacy of the business. Check out eight tips for controlling Asian rust in soybeans:

1.    Toilet void: the elimination of volunteer soybean plants and the absence of soybean cultivation in the off-season reduce the chances of the fungus migrating from a volunteer plant to the commercial crop.

2.    Sowing planning: sow at the recommended time, whenever the weather is favorable, with early cycle cultivars and at the beginning of the planting calendar.

3.    Preventive applications: It is recommended to use fungicides preventively and when the first symptoms appear.

4.    Interval between applications: respect the intervals (up to 15 days) between recommended applications and doses.

5.    Use of protective fungicides: This group of products is very important in the management of resistance and acts preventively, controlling the disease even before it penetrates the plant's plant tissues. For better results and use of this tool, it is important to associate it with the application of systemic products.

6.    Application quality: use of well-maintained, calibrated equipment, with tips in good condition, correct dosage, application rate appropriate to the stage of the crop, in addition to taking care of the temperature and winds at the time of application, are some points that must be observed.

7.    Respect the product leaflet: follow the instructions inherent to each product present in the leaflet, such as dosage, application rate, interval between applications, moment of application in relation to temperature, presence or absence of the fungus and presence of wind.

8.    Monitoring: It is necessary to adopt a strategy of continuous monitoring of crops so that rural producers' decision-making becomes increasingly assertive. Always consult a qualified professional to extract the best results from each tool.