Monitoring in Paraguay and Brazil identifies soybean rust in volunteers, kudzu and collectors

Although Asian soybean rust has not yet occurred in commercial crops, the Paraguayan monitoring service has detected the presence of the fungus Phakopsora pachyrhizi, which causes the disease, in volunteer soybean plants (not cultivated and born spontaneously) and in kudzu (Pueraria lobata), alternative host of the fungus. In Brazil, spores of the rust fungus were identified in collectors.

At the end of October, in monitoring carried out by the National Seed Quality and Plant Health Service (SENAVE) of Paraguay, the occurrence of soybean rust was detected in volunteer soybean and kudzu plants, in the municipalities of Capitán Meza and Pirapó, in the department of Itapúa. No occurrences have been detected so far in commercial crops, but SENAVE issued a warning to producers. “The guidance was to intensify monitoring and carry out control at the appropriate time, especially in more advanced crops and if weather conditions are favorable, due to the presence of inoculum in the region”, explains researcher Cláudia Godoy, from Embrapa Soja. .

In Brazil, collectors from the Institute of Rural Development of Paraná (IDR – Paraná) detected spores of the fungus that causes rust, on October 26, in Santa Helena, western region of Paraná. There is also no record of the disease occurring in commercial crops in Paraná, which are still in the initial phase of development. “However, the identification of spores is an indication of the presence of inoculum in the region, indicating the need to intensify monitoring in crops, especially those that were sown early”, advises Cláudia Godoy.

During this same period, in the previous harvest, the researcher explains that there were no reports of the disease, probably due to the drought that delayed the sowing of crops. “In 2021, the rains started earlier and the arrival of cold fronts, with rain and winds, favored the dispersion of spores from inoculum sources left over from the winter”, assesses Cláudia Godoy. “The implementation of crops has advanced quickly, concentrating sowing. In these first sowings, there is normally an escape of rust through the smallest rust inoculum that was reduced with the sanitary vacuum,” she says. 

When the sanitary void is unable to completely eliminate volunteer plants and alternative hosts, these may remain and serve as inoculum for disease in the crop. “Therefore, it is necessary for producers to monitor their crops and monitor the occurrence of spores on the IDR-Paraná website and on the Antirust Consortium website, since the fungus is spread by the wind”, he warns.Soybean rust - Rust- Asian soybean was first identified in Brazil in 2001, and since then it has been monitored and researched by several public and private centers. According to the Antirust Consortium, this disease, considered the most severe in the crop, can cause losses of up to 90% in productivity if not controlled.

Soybean rust

Asian soybean rust was first identified in Brazil in 2001, and since then it has been monitored and researched by several public and private centers. According to the Antirust Consortium, this disease, considered the most severe in the crop, can cause losses of up to 90% in productivity if not controlled.

Monitor the occurrence of the disease:

• Antirust Consortium website: http://www.consorcioantiferrugem.net/

• Application available on the Apple Store and Google Play.

• IDR Rust Alert - Paraná: cutt.ly/AlertaFerrugem

•  SENAVE (Paraguay) - https://www.senave.gov.py/noticias/1059