Phyllachora Leaf Spot
Phyllachora penniseti Syd.
Symptoms: Leaves can be covered with numerous small,
elongate, dark or black pustules that are 2-3 mm long when isolated
but become confluent in mass. Both surfaces of the leaves can
be affected. Symptoms usually develop after most vegetative growth
has occurred or during grain fill.
Pathogen and disease characteristics: Pseudopycnidia
develop in the stroma under the epidermis. Elliptical, cylindrical,
unicellular, hyaline conidia measure 10-15 × 2.5-3 µm
Host range: Pearl millet, napiergrass (Moreau
1949). Also described on Pennisetum benthami Stend.
Geographic distribution: Chad, Niger, Tanzania (Wallace and Wallace 1949). Republic of
Guinea (and possibly Uganda, see below) on napiergrass (Moreau
Nomenclature discrepancies: Synonyms or similar pathogens:
Described as anamorphic Placosphaeria sp. in Saccas (1954) and Jouan and Delassus (1971).
Leptosphaeria penniseti was isolated from napiergrass in
Uganda was associated with Phyllachora and Stagonospora
(Moreau 1949). Saccas (1954)
indicates asci and ascospore dimensions of L. penniseti
were consistent with Phyllachora penniseti, although
dimensions of L. penniseti differ from P. penniseti
in Moreau (1949).
Alternative disease name: Tar spot.
Seed transmission: Not demonstrated to be transmitted
Primary citations: Saccas 1954,
Jouan and Delassus 1971.
Department of Agriculture
The material on this page is in the public
Original posting: June 5, 1999.