T
he joint large scale use of sus-
ceptible varieties, the presence
of host plants and favorable
environment over the past six
growing seasons resulted into
a real explosion of damages caused by
rice blast, a disease caused by the fungus
Magnaporthe oryzae, in the rice fields in
South Brazil. Rio Grande do Sul and Santa
Catarina represent, together, 80% of the
national rice crop and endured serious
outbreaks of rice blast in all the produc-
ing regions over the past growing seasons.
The vast number of strains of the fungus
Brrrr
Riceblast,diseasecausedbyfungi,posesa
challengetoresearchersandproducersintheir
effortstokeepcontrolovertheinfestations
andthesanitarystatusofthericefields
and the absence of a map of the genetic
resistance and of the pathogen, as well as
the difficulty in operating and the limited
efficiency of the pesticides, affect the ef-
fectiveness of any control measures. The
dissemination of the disease caused loss-
es of up to 100% in some farms, drove up
the production cost and has left farmers
and researchers sleepless. The use of fun-
gicides in the farms in Rio Grande do Sul
went up a staggering 700%. Seven years
ago, the pesticide was only applied in 20%
of the areas, volume that has approached
Inor Ag. Assmann
60
