ChileanJAR

A review was done of the information available in the files of the Chilean Wheat lmprovement Program (INIA) on the reaction to rusts (Puccinia gramínis tritici Eriks. & Henn., P. striiformis West. and P. recondita Rob. ex Desm.) of the wheat varieties included in yield trialsand international rust nurseries established at La Platina Experiment Station (INIA), Santiago, Chile. The objective of this study was to determine the relative importance of each rust, based Qn its mean percentage of infection observed each year, during the period 1960-1979. The yield trials contain wheat unes adapted to Central-North Chile; this material is selected every year for resistance to rusts, under local conditions. The international rust nurseries, organized by the USDA, contain foreign introduction material. Every year, about 3.000 wheat lines were studied. A great variation in the severity of infection was observed among the 20 years anal ized. On the international nurseries, rust attacks were more severe than on the yield -trials. This could be explained by the fact that the introduction material was selected for resistance in other countries, against physiologic races of rusts different to those that are present in La Platina. P. graminis was developed with artificial infections and reached the highest levels of infection. P. striiformis and P. recondita were developed under natural infection. The first one was more important causing moderate to low severity attacks every year. Though attacks of P. recondita of certain importance were observed, these were isolated, and in about half of the years the infection was so low that notes for this rust were not taken.