Zonate Leaf Spot
Gloeocercospora sorghi Bain & Edgerton
Symptoms: Foliar lesions appear as water-soaked spots
that develop tan centers and dark brown borders and measure 3.5-5
× 2-3.5 mm. Spots enlarge, forming roughly semicircular blotches
covering about half of the leaf width. Blotches are various shades
of dark brown mottled with pale tan spots that may appear as concentric
rings of alternating tan and brown.
Note that disease symptoms of zonate leaf spot illustrated
in Williams et al. (1978) were later
attributed to dactuliophora leaf spot (Tyagi
1985). Symptom expression of and differentiation between these
two diseases need to be clarified.
Pathogen and disease characteristics: Conidia borne
on short, erumpent stromata are attenuate-obclavate, hyaline,
multiseptate, and approximately 74.5-2.2 µm. In moist weather,
tiny, salmon-colored globules of conidial masses on the foliar
lesions are visible with a hand lens.
Host range: Pearl millet, sorghum.
Geographic distribution: United States, Tanzania (Wallace and Wallace 1949), Malawi (Wiehe 1953).
Nomenclature discrepancies: None.
Seed transmission: Very infrequently isolated from seed
(Wilson et al. 1993). Transmission
by seed has not been demonstrated.
Primary citation: Luttrell 1954.
Department of Agriculture
The material on this page is in the public
Original posting: June 5, 1999.