Claviceps paspali F. Stephens & J.G Hall

Synonyms

Sclerotium paspali Schw.
Spermoedia paspali Fr.
Ustilagopsis deliquescens Speg.
Sclerotium paspali P. Henn.
Claviceps rolfsii F. Stephens & J.G. Hall
Spermoedia rolfsii Seaver
Spermoedia stevensii Seaver
Claviceps deliquescens (Speg.) Haumann

Description

Sclerotia formed in the fertile florets of spikelets and replacing the ovaries, globose, 2-5 mm in diameter, yellow-grey, surface rough when mature.

Conidia of two types

  • macroconidia formed on narrow, flask-shaped terminal conidiogenous cells on the sphacelium and later immersed in honeydew, oblong-slightly clavate, 7.5-22 x 4-6.5 µm, hyaline, aseptate, usually distinctly biguttulate.
  • secondary conidia developed singly at the tips of sterigmata from germinated macroconidia above the honeydew surface, pyriform, 8-12 x 4-6 µm, aseptate, hyaline.

Ascostromata 1-3, rarely 5 per sclerotium, each consisting of a subglobose capitulum, 1-3 mm in diameter, brown, slightly papillate, borne by a slender stipe up to 10 mm long, white.

Perithecia completely immersed in and covering the capitulum, oval, 190-340 µm x 80-175 µm.

Asci cylindrical, 120-176 x 2.5-4.5 µm.

Ascospores filiform, 50-147 x 0.7-1 µm, hyaline.

Hosts
   
Host family: Poaceae
   
Host species: Paspalum dilatatum
Paspalum distichum
Paspalum notatum
Paspalum paspalodes
Paspalum scrobiculatum
Paspalum urvillei

Distribution

ACT, NSW, QLD, SA, VIC, WA

Comments

Sclerotia of C. paspali produce a range of alkaloids, including dihydrosetoclavine, palliclavine, paspalaclavine, paspalic acid, paspalicine, and paspaline, which can cause mycotoxoses in mammals grazing on ergot-infected paspalum paddocks.This fungus has had a significant effect on the Australian livestock industry, particularly in coastal areas in New South Wales and Queensland since the first observed outbreaks of “paspalum staggers” in the summer of 1935-1936 (Noble 1936; Cawdell-Smith et al., 2007). Langdon (1963) believed that the fungus had entered Australia very soon before its detection. C. paspali is common wherever host Paspalum species grow in Australia, particularly during the late summer-early Autumn months. Langdon and Champ (1954) definitively demonstrated that insects, and particularly blowflies, which fed on ergot honeydew from infected Paspalum plants could disperse viable macroconidia to uninfected Paspalum flowers. When Langdon undertook his ergot studies the existence of secondary conidia was either overlooked or perhaps thought to be due to sporulation of another fungus. In his documentation of the first acknowledged epiphytotic of C. paspali in Australia, Noble (1936) stated that “Plants were frequently seen with globules of honeydew, creamy white in colour because of the presence of large numbers of germinating conidia”. This statement suggests the presence of secondary conidia of C. paspali during the 1935-36 outbreak, so it is possible that these airborne conidia played a bigger role than insects in the rapid spread of C. paspali in the mid 1930’s and in later epiphytotics.

Highslide JS
Claviceps paspali on Paspalum sp. - BRIP 52198.
Scale bar = 1 cm.
Highslide JS
Claviceps paspali on Paspalum dilatatum.
Highslide JS
Claviceps paspali on Paspalum dilatatum.
Highslide JS
Claviceps paspali on Paspalum dilatatum - BRIP 8599.
Scale bar = 10 µm.
Highslide JS
Claviceps paspali on Paspalum dilatatum - BRIP 8599.
Scale bar = 10 µm.