Progress of Asian soybean rust and airborne urediniospores of Phakopsora pachyrhizi in southern Brazil

Summa Phytopathologica

Jefferson Fernandes Do Nascimento²  João Batista Vida¹  Dauri José Tessmann¹  Laércio Zambolim¹  Rafael Augusto Vieira¹  Ricardo Ribeiro De Oliveira¹ 

[1] ,Universidade Federal de Roraima Departamento de Fitotecnia Boa Vista RR

关键词: soybean;    soybean disease;    epidemiology;    Pakopsora pachyrhizi;    epidemiologia;    soja;   

DOI  :  10.1590/S0100-54052012000400002

来源: SciELO

【 摘 要 】

Asian soybean rust, caused by the fungus Phakopsora pachyrhizi, was reported at epidemic levels in 2003/2004 and is the main soybean disease in Brazil. The aim of this study was to investigate the spread of Asian soybean rust and to quantify airborne urediniospores in the region of Campo Mourão, Paraná State, Brazil. Three experiments were conducted under field conditions during the 2007/08 and 2008/09 crop seasons. Using the disease gradient method, provided by the application of increasing levels of the fungicide tebuconazole, four Asian soybean rust epidemics at different intensities were obtained in each experiment. To quantify the urediniospores, weathercock-type spore collectors were installed during and between the two crop seasons. Disease progress curves were plotted for each epidemic, and maximum severity was estimated. The curves were fit to the logistic model, which provided higher coefficients of determination and more randomly distributed residuals plotted over time. Analyses of the area under the disease progress curve showed that the largest epidemics occurred in the 2007/2008 crop season and that the progress rates were higher for severity, even among plants protected with the fungicide. The number of urediniospores collected in the air was related to the presence of soybean plants in the cultivated crops. The quantity of urediniospores was also positively correlated to the disease severity and incidence, as well as to cumulative rainfall and favorable days for P. Pachyrhizi infection.

【 授权许可】

CC BY   
 All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License