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          Fresh urediniospores of Uromyces striatus germinated after 90 min. in a saturated atmosphere and reached 95 per cent in 4 hr. Stored spores at 20-25 C lost their germination and infectivity after 60 and 140 days respectively. The latent period increased by 1-day with stored urediospores. At -10C, the stored spores continuously caused infection on alfalfa even after 220 days of storage. Rust infections occurred twice during 1980-1981.the first outbreak occurs during May-June while the second during October-November. The infections are mild during winter. The pathogen produced 10-30 per cent teliospores within each old pustule. On detached leaves, teliospores appeared after 19 and 35 days of inoculation at 28 and 20C respectively and have no role in disease occurrence. The rust overwinters in uredial form in Central Iraq.               

Key words: Alfalfa rust, Uromyces striatus, Etiology, Overwintering