OCCURRENCE OF BLAST FUNGUS (PYRICULARIA-G RISEA) ON WHEAT AND RYE IN THE SAVANNA REGION OF CENTRAL BRAZIL

The present work reports the natural occurrence of blast in wheat and rye in the Savanna region of Central Brazil. In May 1993, on a field t rail of the Internacional Heat Stress Genotype Experiment at the Cerra dos Agricultural Research Center (EMBRAPA-CPAC), Planaltina, DF, sympt oms on the heads of the wheat cv. Kanchan showed similarities to that described in the literature for the wheat blast. The confirmation of t he causal agent, Pyricularia grisea (Cooke) Sacc., was made after isol ation on PDA medium and observation of morphological characteristics o f the fungus using light microscope. Under field conditions, the white ness symptoms had attained 48.6% of the heads. These infected heads sh owed a 7.4% reduction in fertile spikes and 10.4% reduction in the num ber of grains when compared to unaffected ones. The reduction in the g rain weight per head at disease levels up to 50% and above were 8% and 29%, respectively. In March 1995, symptoms of the leaf whiteness of t he heads were also observed on wheat cv. BR 10-Formosa, and rye cv. BR 1 crops at CPAC. The occurrence of P. grisea was confirmed as describ ed above.