Corynebacterium rathayi . [Descriptions of Fungi and Bacteria

Abstract

Abstract A description is provided for Corynebacterium rathayi . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Dactylis glomerata ; also naturally on Cynodon dactylon (4, 336) and Secale cereale (6, 663). By artificial inoculation using nematodes as vectors on Triticum aestivum, T. durum, T. dicoccum and T. pyramidale (Sabet, 1954). DISEASE: Yellow slime disease of cocksfoot (orchard grass). Yellow bacterial slime covers upper parts of plants, especially the inflorescences. Such parts often become dwarfed and distorted and inflorescences may fail to emerge from sheaths, which are firmly stuck together by slime. Vessels and parenchyma are invaded by bacteria. Very similar diseases have been reported on other grasses as caused by different species. These include Corynebacterium tritici (CMI Descript. 377), C. agropyri on Agropyron smithii, C. iranicum on wheat, and Bacillus mucilaginosus koeleriae on Koeleria glauca . The first is often reported and of wide distribution, but the others have been reported only once or very few times each. It is possible that all belong to one species, perhaps a variable one, or one with different formae speciales . GEOGRAPHICAL DISTRIBUTION: N.W. Europe, N. America, New Zealand (CMI Map 156, ed. 2, 1966). Also recently reported from Japan (51, 1579). TRANSMISSION: Seedborne. The pathogen occurs in slime on seed from partially infected inflorescences. Wet periods in May and June evidently favour the spread of the disease in Denmark, where it has been observed that the percentage of infected seed is maximum in years following two successive years in which May and June were wet (Skou, 1965). The aetiology is not fully known. The only records of successful artificial inoculation into Dactylis glomerata are those of Dowson & D'Oliveira (14, 514), who used bacterial slime inoculated with a scalpel into leaf sheaths at the bases of young, vigorously growing shoots; Severin & Docea (50, 1047y) used cultures, but unfortunately give few details. Other workers have reported no success with either pure cultures or with slime. The nematode Anguina tritici , which transmits the closely related C. tritici on wheat, has been shown by Sabet (1954) to carry C. rathayi into wheat and cause an identical disease, but this nematode does not go to Dactylis . Sabet therefore suggested that an unknown nematode vector may be involved in transmitting C. rathayi . Absence of the necessary vector may explain the frequent failure of inoculations. Direct plant to plant transmission seems very unlikely.