Epidemiology of black rust on Wheat (P.g. tritici) and methods of control under the cultural conditions of Belgium.
The results of inoculation experiments begun in 1956 at the Institut Agrono-mique, Heverlee, demonstrated that P. graminis may appear on the wheat crop as long as a month before the normal period (2nd half of July). These observations agree with Ponchet's findings at Versailles [36, p. 12]. In view of the absence of an aecidial host and the late development of the rust, it is evidently unable to overwinter in Belgium, and is re-introduced every year by S. and S.E. winds. The damage caused by P. graminis depends largely on the date of its appearance. In 1958, for example, when it was first detected on 1 July, infection was relatively severe though unaccompanied by appreciable reductions in yield. Although most wheat vars. cultivated in Belgium are susceptible, they commonly escape serious injury on account of their precocity combined with the tardy development of the pathogen. Hence control may be effected by systematic breeding for early maturity, especially among spring wheats.