|
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. |