Previous View
APSnet Home
Plant Disease Home

Disease Note.

Septoria orobina on Sainfoin: A New North American Record. B. Berkenkamp, Agriculture Canada, Lacombe, Alberta T0C 1S0. J. Meeres, and J. Bissett. Agriculture Canada, Lacombe, Alberta T0C 1S0, and Biosystematics Research Centre, C.E.F., Ottawa, Ontario K1A 0C6. Plant Dis. 71:651. Accepted for publication 6 February 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0651A.

Septoria orobina Sacco was isolated from leaf spots on sainfoin (Onobrychis viciifolia Scop.) in 1978 at Lacombe, Alberta, Canada. Infection is characterized by pale, diffuse, mottled lesions, followed by chlorosis and abscission of leaflets. The symptoms, cultural characteristics, and microscopic features of the fungus are similar to those described by Hughes in 1942 from Wales (1). This leaf spot is easily differentiated from the more common and severe disease caused by Ascochyta fabae Speg., which produces leaf spots with sharp, dark brown margins and globular exudations of conidia under moist conditions. S. orobina produces lesions lacking distinct margins and forms spiral-shaped extrusions of conidia. We have observed this disease over several years and have carried out Koch's postulates. Although this disease does not appear to be a major threat to the production of sainfoin, its distribution now appears to be much wider than previously known. Voucher specimens and dried cultures have been deposited at the Biosystematics Research Centre as DAOM 171072.

Reference: (1) S. J. Hughes. Trans. Br. Mycol. Soc. 32:60, 1949.