ChileanJAR

In 1986, there was an intense attack of leaf rust (Puccinia recondita), in the north-central part of Chile. Studying this infection in the Regional Vield Trials of bread and durum wheats, at Vallenar, La Serena, and Ovalle, big differences were found. At Vallenar, the durums were completely resistant to the disease, while the bread wheats had, in the average, a 35% of infection. At La Serena, the durums had 32% of infection and the bread wheats 17%. In Ovalle, the durums had 53% and the bread wheats 25%. At La Platina (lNIA, Santiago), the average attack to all varieties in the yield trials was 9.5%, in the bread wheats, and 25%, in the durums. This great infection on durums was due to a possible change in the races, as many of the varieties considered resistant to the disease, this year were completely susceptible. Only 42 of the durum varieties studied in yield trials showed resistance and 178 were susceptibles. In the average, the 42 resistant varieties yielded 10% more than the 178 susceptibles, and this difference was significant at 1%. The drop of yield was less than expected, due to the lateness in the development of the disease. The durum wheats, sown in a normal period had an average of 25% of infection and 67% in the late sowings.