The relative efficiency of systemic seed treatment fungicides singly and in mixture on leaf blast
(Pyricularia grisea) was studied in field and blast nursery experiments, under natural conditions of infection. In the
field experiments the treatments included two culivars (Rio Paranaíba and Guarani for upland and Cica 8 and
Metica 1 for irrigated rice experiments) and pyroquilon singly at recomended dose (400g/100kg seed) and in
mixture with difenoconazole and fludioxonil besides thiabendazole and carboxin + thiram at different doses. In the
blast nursery experiment, the treatments consisted of two cultivars (Rio Paranaíba and Guarani) different doses of
pyroquilon singly and in mixture with difenoconazole. The percentage leaf area, area under disease progress curve
and biomass production were used as criteria of evaluation of the efficiency of tested fungicides. There was no
differential response of cultivars to fungicide seed treatments. The efficiency and residual effect of pyroquilon seed
treatment at the recomended dosage of 400g a.i./100kg seed was superior than all other treatments including nontreated
control in both upland and irrigated rice experiments. The fungicide mixture of pyroqilon with triazoles such
as difenoconazole and fludioxonil did not increase the efficiency of seed treatment. The dry matter production
significantly increased in all treatments of pyroquilon as compared to non-treated controls.