Your are here:

Cercospora leaf spot

Scientific Name
Cercospora apii
Scientific Author
Fresen.
Taxonomy
(Ascomycota: Dothideomycetes: Capnodiales: Mycosphaerellaceae)
Risk
Medium
Status
Exotic Disease Occurence in Thailand
Reliability
High
Download
PDF

Page menu options:

Diagnostic Images

Conidiophore
Close
Caption
Conidiophore of Cercospora apii. Scale bar 10 µm.
Source
Warangkana Sae-Uang Department of Agriculture, Thailand
Image Options
Close
Diagnostic Images (7)
Diagnostic Notes

Sometimes saprobic, symptomless, on necrotic leaves, stems and fruits or on lesion caused by other fungi (secondary invader), but mostly pathogenic on ferns and phanerogams, on living and fading leaves, stems and fruits, often on weakened plants, causing leaf spots. Lesions subcircular to angular – irregular, mostly 1-10 mm diam., occasionally larger or confluent and forming large patches, young spots sometimes pale greenish, olivaceous or yellowish-ochracous, later usually pale to medium dark brown, old spots often turning grayish brown, dingy grey to grayish white, in advanced stages of the disease, central tissue sometimes droping out leaving shot- hole effects, margin indefinite or surrounded by a narrow to moderately wide, brown, reddish or purplish violet border, occasionally with a diffuse halo, yellowish-ochraceous reddish or puplish violet. Mycelium internal. Stromata lacking to well developed, 10–50 µm diam., substomatal to intraepidermal, composed of swollen hyphal cells, subglobose to somewhat angular in outline, usually 2–6 µm diam., olivaceuos to medium brown. Conidiophores solitary or in small to moderately large fascicles of 2–30, rarely more, loose to dense, arising from internal hyphae or stomata, emerging through stomata or erumpent though the cuticle, erect, straight, subcylindrical or basal part cylindrical and upper fertile part slingtly to strongly geniculate – sinuous (geniculation mostly connected with connidiogenesis and proliferation of conidiogenous cells) unbranched or occasionally branched, (10-) 20-350 (-450) x (2-) 3-6 (-8) µm (very long conidiophores only formed under moist conditions, e.g., in moist climate or moist chambers), continuous to pluriseptate throughout, pale olivaceous to medium brown, often paler towards to apex, smooth, rarely rough-walled, wall thin to somewhat thickened. Conidiogenous cells integrated, terminal or intercalary, conidiophores occasionally reduced to conidiogenous cells, 10-60(-80) µm long, occasionally unilocal, determinate, but usually multilocal, sympodial, occasionally proliferation enteroblastically percurrent; conidiogenous loci conspicuous, situated at small shoulders caused by sympodial proliferation of the conidiogenous cells, or more or less flat, not protruding above the level of the wall of the conidiogenous cell, loci subcircular in outline, planate, thickened and darkened, (1.5-) 2-3.5 (4.5) µm wide. Conidia solitary, under moist conditions occasionally in short chains, young, short conidia often cylindrical or obclavate – cylindrical, fully developed long conidia always acicular(gradually attenuated from base to top), (10-) 30-250 (-380) x (1.5-)- 2-5 (-5.5) µm (very long conidia only formed under moist conditions, under dry conditions often uniformly short), (0-) 3- 25 (-30)- euseptate, hyaline, occasionally with a faintly greenish tinge, smooth, thin-walls, tapering to subacute apex, sometimes subobtuse in short conidia, base of cylindrical and acicular conidia truncate not attenuated or only slighty narrowed at the very base (at the hilum) in short obclavate conidia with somewhat obconically truncate base, (1.5-) 2.3 (-4.5) µm wide , thickened and darkened. Description taken from Crous and Braun (2003).


Note: Crous and Braun (2003) emended the description of Cerscospora apii so that it accommodated the morphological variation seen in many similiar species of Cercospora, which were reduced to synonymy with it. This approach was foreshadowed by Ellis (1971) who listed several probable synonyms of Cerscospora apii. Cercospora apii was originally described from Apium graveolens (celery).

More Information
Specimen Contact
Warangkana Sae-Uang
Author
Pisawongprakarn, S., Sae-uang, W., Beasley, D.R. & Shivas, R.G. (2011)
Created
01/02/2011 12:48 AEST
Last Updated
01/02/2011 17:42 AEST
Citation
Pisawongprakarn, S., Sae-uang, W., Beasley, D.R. & Shivas, R.G. (2011) (2011) Cercospora leaf spot (Cercospora apii) Updated on 2/1/2011 5:42:31 PM Available online: PaDIL - http://www.padil.gov.au.
Image Use
Free for use under the Creative Commons Attribution 3.0 Australia License

Loading