Introduction to Fungi, Third Edition

352 HYMENOASCOMYCETES: PYRENOMYCETES
Fig12.26 Claviceps purpurea. (a) Head of rye (Secale cereale) bearing several sclerotia (ergots) of Claviceps purpurea. (b) Rye
inflorescence at anthesis bearing two drops (arrowed) of the honeydew or Sphacelia conidial state of C. purpurea. A fly has landed
near these drops. (c) Germinated sclerotium showing several stalked perithecial stromata.
which the host grass flowers are open and
therefore susceptible to infection.
Ergotism
The effect of infection on the host can result
in yield reduction by as much as 80% of seeds.
Severe though this reduction in crop yield
is, the consequences of consumption of ergotcontaminated
grain can be disastrous to herbivorous
animals and humans alike. The purple
sclerotia contain a number of toxic alkaloids
(Buchta & Cvak, 1999) and if they are eaten they
can cause severe illness and sometimes death.
Even at relatively low concentration there may
be severe effects on feed refusal, lack of weight
gain in farm animals and on reduced fertility,
resulting in part from agalactia, the inability to
produce sufficient milk to nourish the young
(Shelby, 1999). One effect of the toxins is to
constrict the blood vessels, and the impaired
circulation may result in gangrene or loss of
limbs. Gruesome descriptions of the symptoms
on humans have been related by several contemporary
authors, e.g. Sidney (1846) who wrote:
The medical effects of ergot, in small doses, have
already been noticed as being extremely powerful,
but if taken to any extent its results on the animal
frame are truly awful. This has been proved by
numerous experiments, of which Professor Henslow
gives a most striking account in his most valuable
notice of this disease; to which he adds a proper
caution against their repetition now the question is
settled. Animals which refused ergot mixed with
their food have been compelled to swallow it, and it
reduced them to a wretched condition. It was tried
upon pigs, and also upon poultry, and the
consequences were sickness, gangrene, and
inflammatory action so intense, that the flesh
actually sloughed away. In some cases, the limbs
rotted off, and no description of animal suffering
has ever exceeded the direful ills thus inflicted.
These experiments were made with a view to
determine whether the ergot of rye, constantly
ground up with the flour in some parts of France,
might not be the cause of the gangrenous disease
so prevalent amongst the poor in certain districts.
The symptoms of these epidemic diseases are