STUDIES ON STEM RUST DISEASE OF WHEAT

Abstract

Wheat (Triticum aestivwn L.) is one of the impottant. food crops in the world and in Egypt. During it's life, wheat is subjected to the attack of numerous diseases patticularly the msts, which play an active pmt in mass production. Wheat stem mst is• one of the common rust diseases in Egypt. The presented results indicated prevalence of stem mst in the Nmthem governorates of Egypt approximately ff!: I 0% to 40 %. Six and five physiologic races of Puccinia graminis tritici could be identified during 1998/99 and 1999/2000, in this respect. Race no. II was the more frequent one.

ll1e study gave evidence to community of the vimlence formula 1.e. 26, Gt+, 9e, 36 and the fommla 26, Gt as the more fi•equent ones during the two successive seasons. However Sr 26 followed by Sr 9e, Sr T1•1 and Sr II were the most effective genes during the two seasons in respect.

ll1e application of the modem nomenclature system for mst races resulted in the community of races i.e. RTK and TTT which were correlated with the dominance of Sr's: 9e, 36, then Sr Sa during 1998/99. On the other hand, races i.e. RKT, RFT, MKT, MFT were

dominant during 1999/2000 and were relevant to Sr's: 9e, II, 6 and

21 so these genes were considered to be more effective during

1999/2000. Conversely, all of the tested races were vimlent to Sr 9b indicating it's defeating.