The construction of a new greenhouse for the Department of Plant Breeding and Genetics in Quinta Normal (Santiago) has permited the initiation of studies on physiological strains of Puccinia graminis tritici and P. triticina in Chile.
The existence in Chile of strains 11, 14, 15 and 17, which had been determined by Vallega, was reaffirmed.
Forty-two varieties of wheat from the United States were tested against a mixture oí strains of P. gmminis tritici, composed predominately of strain 15 which is the most virulent in the country, and 5 of them reacted as if immune.
The importance oi discovering the manner in which P. graminis passes its critical periad in Chile is emphasized.
Details of the method of determining physiological strains of P. graminis tritici and P. triticina are given.
Two new strains of Puccinia triticina, 71 and 85, are added to the list of those already known to exist in Chile.

1 Ing. Agr. del Departamento de Sanidad Vegetal