Eficiência de tratamentos alternativos no controle de Pyricularia grisea em sementes de trigo

Abstract

The present study aimed to examine alternative methods of control of Pyricularia grisea in wheat seeds, one primary source of blast disease. The treatments sodium hypochlorite (2%; pH11,5; 50C; 10min) and hot water (55°C/5min) were selected after preliminary trials that examined the effect on germination of several reagents, at different concentrations, temperatures and period of submersion. Their efficiency in controlling P. grisea in wheat seeds and its transmission to seedlings was studied in seed lots of 400 in four replications in a randomized block design. The fungal incidence was analyzed through blotter test employing 22°C and photoperiod of 12 h from the second to fourth day, seed germination at the seventh day through visual emergence of germ tube and transmission to seedlings at the seventh and 14th days through identification of P. grisea conidia from necrotic lesions of any aerial tissues. The present data revealed that sodium hypochlorite (pH 11.5/50°C/10min) was effective in controlling P. grisea in wheat seeds because it decreased the initial incidence from 57.7% to 2.25% but with deleterious effect on germination. This treatment reduced the fungal transmission to seedlings from 39.7 to 0.5%. © by the Brazilian Phytopathological Society.