The importance of proper management of Asian rust

The increase in planted area and gains in productivity have been determining factors for the performance of the soybean production chain, as well as for meeting the high global demand for the oilseed and its by-products. (Graphic 1.)

To reach its maximum productive potential, soybeans need to develop, throughout the crop cycle, free from any interference. In Brazil, particularly, Asian rust or soybean rust has been one of the main obstacles for producers. The disease, caused by the fungus Phakopsora pachyrhizi, has remained since 2001, when it arrived in the country, among the most aggressive occurrences in crops, leading to losses of 10% to 90% of the affected areas. The pathogen that causes rust found the ideal climatic conditions for its development in the country. Recently, it has also acquired resistance to active ingredients in fungicides. The fungus Phakopsora pachyrhizicreated worrying survival strategies, to the point of leading companies, Government and researchers to work hard on developing innovative methods to control rust. The use of fungicides, by the way, is not the only tool recommended for effective control of Asian rust. It is important that the producer also adopts other preventive mechanisms, such as genetic resistance, cultural control, crop monitoring, respect for sanitary conditions and planting at the beginning of the recommended season. Regarding fungicides, it is essential that the producer opts for a preventive and efficient treatment program from the first applications.

 Fungicide program – After several years of studies, the DuPont Crop Protection team of researchers developed a new fungicide program to control soybean rust and other oilseed diseases. The treatment is anchored in an application program that includes the alternate use of the different modes of action of the products Aproach Prima (Picoxystrobin + Ciproconazole) and Vessarya (Picoxystrobin + Benzovindiflupir). The graphs below show the results obtained by this program, data that was compiled in more than 450 experimental fields installed in the main Brazilian soybean regions. The line of research, in short, compared the performance of DuPont's fungicide program to the standard treatment that has been adopted by producers.

According to the scientists and researchers involved in the work, the high productivity of DuPont's 450 experimental fields - and the superiority of the results obtained compared to those of the producer's standard treatment - is related to the effective control of rust and other soybean diseases, including target spot, powdery mildew and end-of-cycle diseases. The success of the treatment, in turn, was due to the combination of Aproach® Prima and Vessarya® fungicide formulations, which form the basis of DuPont's fungicide program. Aproach® Prima contains the most powerful Strobirulin on the market associated with a Triazole. Vessarya® brings together in the formula a mixture of the active ingredients Picoxystrobin and Benzovindiflupir, which do not require the use of adjuvants in spraying. Benzovindiflupyr is today considered the most potent Carboxamide available in Brazil.

Figure 3 shows the DuPont program side by side with the farmer's program. Note that the average productivity of the DuPont fungicide program was 67,7 bags of soybeans per hectare, compared to 59,8 bags per hectare for the standard program or producer program.

It is also important to highlight that the combined use of fungicides contributes to the sustainability of existing rust control technologies. The producer must also pay attention to the following management recommendations:

 ·         Carry out preventive application of fungicides, starting applications before the entry of diseases

·         Respect the doses and application intervals indicated in the leaflet

·         Apply fungicide program containing multiple modes of action for disease control

·         Make at least 2 applications of multi-site fungicides per soybean crop cycle

·         Make a maximum of 2 applications of Carboxamide-based fungicides per soybean cycle

·         Respect the “sanitary void” period

·         Use other control strategies, such as using soybean varieties with genetic tolerance, short-cycle varieties and adopting good fungicide application technologies.