8th INTERNATIONAL WHEAT CONFERENCE

The moST ImPoRTANT WheAT dISeASeS IN BRAzIL
Flávio Santana¹, Eduardo Caierão ¹ ,
Pedro Luiz Scheeren ¹ , Márcio Só e Silva ¹ ,
Márcia Chaves ¹ , João Leodato Nunes Maciel ¹
¹ Embrapa Wheat researcher. Brazilian Agricultural Research Corporation – EMBRAPA.
Rodovia BR 285, km 294. Caixa Postal 451. Passo Fundo, RS, Brazil. Corresponding author:
F. Santana; E-mail address: E-mail Address of presenting author: fsantana@cnpt.embrapa.br
Brazil is the largest country in the South America, with a total area of 8, 514, 876 km 2
(851, 487, 600ha). The wheat growing area in 2008 was 2, 373, 572 ha, which 90% are
placed at the south region of the country, where the majority of the farmers uses the no
tillage system. In that year the total production was 5, 886, 000 t that gave an average of
2, 480 kg /ha. In the central part of the country, named “Cerrado”, because the weather
conditions (dry and sunny), the yield average can reach 6, 000 kg/ha or even more, but
the wheat area there is still too low: 68, 000 ha in 2008. In spite of the weather there to
be able to promote good conditions to the plant growing and unsuitable environment to
some important wheat pathogens, there are some restrictions to expansion area for wheat
in the Cerrado, and one of them is a severe fungal disease which the success or fail in the
control is crucial to the wheat production there: wheat blast. The weather conditions there
is very appropriate for the Magnaporthe grisea infect wheat and spread out. This disease
is relatively new in Brazil, with a first report in 1986 at the Paraná state, but became one
of the most important wheat diseases because there is no resistant cultivar, the chemical
control efficiency is too low and the yield losses can reach 100% in a raining year.
For the 90% of the Brazilian wheat, in the south, the main diseases are: Fusarium head
blight (Gibberella zeae), leaf rust (Puccinia triticina), and the foliar diseases caused by Pyerenophora
tritici-repentis, Bipolaris sorokiniana and Stagonospora nodorum. These three
last pathogen became very important in the country, mainly in the south, because the
relative high humidity during the crop season and the no tillage system, which gives
an excellent condition for these necrotrophic pathogen to survive from one year to the
following on the stubble. The importance of the stem rust is the number of race of the
pathogen which quickly overcomes the resistance of the cultivars. In Brazil 56 races were
identified until now. The fusarium head blight is a wide spread pathogen onto the wheat
growing area of the country and the weather conditions, especially in the south, are ideal
to the pathogen.
In order to manage and to control the diseases cited above some strategies are applied:
for the blast disease the only efficient way yet is to avoid the favorable conditions to the
disease development. The control percentage by fungicides is not higher than 50 or 60%
in a severe attack by the pathogen. Researchers at Embrapa Trigo are working hard to find
good resistance source at wheat germplasm and introgress effectives genes into wheat
cultivars.
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