| Título: | Soybean rust studies in Southern Brazil. |
| Autores: |
COSTAMILAN, L. M. GODOY, C. V. SOARES, R. M. YORINORI, J. T. ALMEIDA, A. M. R. |
| Fecha: |
2014-10-17 2014-10-17 2006 2007-01-23 |
| Publicador: | Repositório Acesso Livre à Informação Científica da Embrapa (ALICE) |
| Fuente: |
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| Tipo: | Resumo em anais de congresso (ALICE) |
| Tema: |
Soja Doença de planta Fungo Ferrugem Doença fungica |
| Descripción: |
Asian soybean rust was first detected by the end of the 2001/02 summer crop season on April 23, in the district of Ciríaco, in Rio Grande do SuI state (RS). In that moment, grain yield loss due to the disease was estimated to be 43% for cultivar BRS 154 and 23% for cultivar BRS 153. In the following seasons, the disease was observed in almost 100% of soybean fields, but in low severity due, basically, to drought which ocurred in 2003/04 and 2004/05 cropping seasons throughout the South of Brazil. In 2005/06, rust occurrence was again widespread, but in low severity,.because of the scarce rainfall distribution in December 2005, and in January and February 2006. Even so, 359 occurrences were registered in RS state and 51 in Santa Catarina state, in the Alert System site of the Antiferrugem Consortium. Only at Embrapa Trigo, 344 samples from 81 districts were analysed, and in 303 of them (88%) confirmed the presence of rust. The districts with the largest number of soybean fields affected by rust were Nonoai (41), Trindade do SuI (24), Chapada (21), Sao Jose das Missoes (20), Floriano Peixoto (19), Gramado dos Loureiros (17), Getúlio Vargas (15), and Rio dos Índios (11). In RS, generally, the disease tends to appear in the reproductive growth stage (99% of the occurrences in the 2005/06 cropping season, being 44% of those in the beginning seed stage - R5). February/2006 was the month with the highest number of evidences (55%), followed by March/2006 (29%). The highest yield losses were observed at the small farm landowners, and that could be related to the lack of rust scoutting, to misidentification of the disease in its early symptoms, or to the delay of the ideal time for fungicide spraying. Epidemiology studies of asian soybean rust have been developed at Embrapa Trigo since 2002/03, in three or four seeding dates using two cultivars. In most cropping seasons, the first symptoms of the disease appeared when plants were in the reproductive stage. The greatest severity and AUDPC (area under the disease progress curve) occurred when the seeding date was delayed. The disease was always less severe or absent in the early-maturing cultivar. Rust chemical control, in the South, has been studied in the National Web Fungicide Efficiency led by Embrapa Soja, and by private groups, and presented at technical meetings. The National Web Trial was conducted by Embrapa Trigo in the cropping seasons of 2003/04 and 2005/06, in which there were no significant differences between the control without fungicide and the other treatments with different types of fungicides, in one or two applications, due to the development of low levels of rust severity. Resistance studies were conducted in the 2003/04 and 2005/06 cropping seasons, in the field, with soybean plant introductions (PIs) and cultivars gathered by Embrapa Soja. In 2004, the genotypes that standed out with the lowest disease indices were PF 001339, BR 993313, and MGBR 48 (Garimpo RCH), and, in 2006, PI 224270, PI 379618TCI, PI 417115, and PI 423956 and the cultivars Shiranui and Kinoshita, with RB (reddish-brown) lesion type and lower sporulation and severity degrees, besides PI 471904, with RT lesion type (reddish-brown with some TAN lesions type). 2006 |
| Idioma: | en |
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