The ergot fungus can multiply both sexually and asexually. From a Sclerotium arise during the growing season several pedunculated fruiting bodies, which have a cap-like shape. They form by fusion of several filamentous fungal cells. The fruiting bodies develop inside numerous hoses (asci), in which the ascospores (seeds) are produced. With the onset of grass and cornflowers, the ascospores are released and spread by the wind. Through the scars of unfertilized flowers they penetrate into the ovaries. This sexual reproduction is defined as a primary infection.
In the (asexual) secondary infection, the conidiospores (conidia) develop from the mycelium of the ergot fungus by constricting cells. They are released by the contact of ear to ear as well as over rain and wind.
In addition, insects that are attracted to honeydew are also important. This is a sweet liquid that the purple-brown ergot fungus forms through the decomposition of grain seeds. The conidiospores finally arrive similar to the ascospores in the fruiting bodies of flowering grasses, for example.
In the fruiting body of the colonized plant, the spores germinate into a mushroom mycelium, which eventually decomposes the ovary. From a newly formed soft mass of honeydew comes out. Later, the mycelium matures to a horny sclerotium, which gets the typical dark purple appearance.
Instead of seeds, the grasses or plants infested with the ergot fungus then only release sclerotia. However, they contain alkaloids ("vegetable ash") which are toxic to the human organism. In their effect, they can be compared with morphine, strychnine and solanine.
If a person ingests sclerotia in large quantities, limbs may die as certain blood vessels are pinched off. Disturbances of the central nervous system may also cause muscle spasms. Also stomach and intestinal diseases are probable.
Even in the Middle Ages, when ignorant of the risks sclerotia were ground together with the grains to flour, terrible consequences of the toxic substances were recorded. Due to these hazards, limit values for the sclerotia content in cereals have been established some time ago. With today's usual cleaning methods for cereals, however, the toxic substances can be sorted out with great certainty in the mill operations. Domestic and farm animals are still at risk, however, if they graze grassy areas that may have been affected by ergot.
The sclerotia of the purple-brown ergot fungus are usually slightly curved, become up to six inches long and often protrude a significant amount from the husks of the cereal plant. The ears or panicles infested by the black fungus are very sticky because of the separated honeydew. Cold and dryness can withstand the sclerotia relatively well.
After they have survived the winter in or on the ground, they go to the heyday of the grasses in the germ state. The best distribution has the ergot fungus in precipitous and cool weather. On the other hand, very hot and dry conditions are dangerous for the crop, as more flowers remain unfertilized. Then they can be infected by Claviceps purpurea.
There is also a high risk of infection from already infested grasses, which are at the edges of the grain fields. If cereal crops bloom unequally and, for example, rye on rye follows in the fruit, spreading of the ergot fungus is facilitated.
Medically, it is now considered proven that alkaloids of ergot fungus can cause intestinal spasms, hallucinations and the death of fingers and toes. These abnormalities are triggered by circulatory disorders. From ancient times, the term stony fire has been used for this limb strangulation. Later, the word ergot fire was added. Technically, the disease is called ergotism today.
The metabolism of an adult human being is so severely impaired by eating five to ten grams of fresh ergot that respiratory paralysis and cardiovascular failure may be followed by a potentially fatal outcome. Reliable investigations warn against damage to human health when around ten milligrams of ergot alkaloids per kilogram of flour occur. The limit for safety is two milligrams per kilogram.
The alkaloids can also be used profitably in medicine. For example, they have hemostatic properties during and after births. Likewise, they help against orthostatic hypotension (low blood pressure) and dizziness immediately after getting up, as well as migraine. From the purple-brown ergot fungus can be obtained the so-called lysergic acid, with which the drug LSD can be produced.Tags: