Drechslera nobleae on Lolium multiflorum in North America [Italian ryegrass]

• Published in: Mycologia Vol. 74; no. 3; pp. 391 - 397
• Main Author: Morrison, R.H
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 01-05-1982; New York Botanical Garden
• Subjects: Cell walls; Conidia; Conidiophores; Fungal spores; Helminthosporium; interspecific Lolium hybrids; Italian ryegrass; Lesions; Plant diseases; Plants; Pycnidia; Septum
• ISSN: 0027-5514; 1557-2536
• DOI: 10.1080/00275514.1982.12021523

Drechslera nobleae, isolated from Lolium multiflorum in Alabama, USA, in 1976, is reported from North America for the first time. Drechslera nobleae is redescribed, and is distinguished from other Drechslera species by its obclavate conidia formed close together at the apex of long, dark brown, unbranched conidiophores; by the first or second cell above the basal cell of conidia being slightly inflated, thinner walled, and paler than other cells, and by conidia germinating mostly from the inflated cell and apical one, but not the basal cell. The pattern of septation during conidium maturation differs from other Drechslera species in that the first septum forms near mid-spore, initially delimiting the region in which the basal and second cells develop. Sterile protothecia, and pycnidia containing unicellular microspores, were formed on agar media and host tissue. In the greenhouse, D. nobleae was moderately pathogenic to L. multiflorum, producing small, brownish-black, sub-oval lesions, and yellowing and tip die-back of leaves. Little or no damage occurred on five other grass species.