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Ergot on Rye
 



Erysiphe
 





Another Modern Fungus-related Problem
 
FUNGAL FOES
Through most of history people have feared fungi. Once regarded as the work of evil spirits or the devil, even in our enlightened era they're still treated with suspicion in much of the western world.

It's easy to see why fungophobia is widespread. Many moulds, and a number of fleshy mushrooms of woodlands and meadows produce small quantities of toxins. Some, like the Destroying Angel, Amanita virosa and its relatives are deadly poisonous and have killed many an unwary diner.

Insidious moulds have caused the most widespread havoc. From the Middle Ages until the mid-1900s, at least 65 poisoning epidemics broke out in central Europe and France when people unknowingly ingested the alkaloids produced by ergot, Claviceps purpurea—a fungus that parasitizes rye. Symptoms of ergot poisoning, or ergotism, include terrible abdominal pains and burning sensations, followed by convulsions, and hallucinations. Some of ergot's alkaloids reduce peripheral blood flow leading to gangrene and loss of limbs.

Once known as St. Anthony's fire, ergotism is rarely a problem for humans now, but it can still affect farm animals. Beneficial derivatives of ergot include a drug that induces childbirth and controls bleeding in newborn babies. Ergots contain lysergic acid from which LSD, a hallucinogenic drug, is derived. It is not clear how or where the lysergic acid in historic cases of ergotism was converted to LSD to give the 'mad' symtoms of victims.

Fungi are responsible for the majority of plant diseases, and have devastated many a food crop. In 1845, the mould Phytophthora infestans turned potatoes throughout Ireland into a rotting mush. Thousands of Irish men, women, and children starved to death. Many survivors fled to North America to make a new life for themselves. In 1847 alone, some 90,000 Irish emigrants headed for Canada.

This wasn't the first time a fungus changed the course of history. Scientists who have studied biblical accounts of famines in Egypt and Israel—and the mass migrations of people that resulted—believe the crops failed because of rusts, a group of fungi that destroy cereal crops.

Almost any food crop you choose to name is at the mercy of at least one fungal blight or mildew. Wheat rusts gave prairie farmers a dismal time in the 1930s, and grape mildews almost destroyed the French wine industry in the mid-1800s. Farmers are constantly on the alert against these pathogenic fungi.

Nor are trees spared from fungal disease. The ravages of the fungus Cryphonectria parasitica (the agent of chestnut blight) almost wiped out the once majestic sweet American chestnut tree. It survived, but only in isolated populations in North America, and it rarely reaches maturity.

Dutch elm disease, first discovered in North America in 1930, has since killed billions of trees, and is now present wherever American elms grow. It is caused by the fungus Ophiostoma ulmi, spread from tree to tree by the native elm bark beetle. A much more deadly strain developed in the North American elm host returned to Europe to play havoc with European elm species (O. novo-ulmi)

Beech stands in the ancient Acadian forest were devastated by beech bark disease in the 1930s. The fungus causing the disease (Nectria galligena) is ferried from tree to tree by an introduced insect, Beech Scale. Fungi are also responsible for Pine blister rust and tar spot on maple.

Apart from a few uncomfortable ailments like athletes foot, fungi do not normally cause serious disease in humans. One exception is histoplasmosis, caused by Histoplasma capsulatum found in bird droppings in contact with soil. It is especially a problem below starling roosts and in bat guano in caves. Symptoms of the disease are similar to those of tuberculosis. Another is fungal endocarditis, an inflammation of the heart tissues caused by a filamentous fungus, Aspergillus fumigatus, or the yeast Candida albicans which causes thrush. Fungal diseases of humans are called mycoses.

Generally, pathogenic fungi are only able to attack if a person's immune system has been compromised. When antibiotics remove a body's healthy bacterial flora they leave the door wide open to fungal infection. Sadly, many AIDS-related deaths are the result of mycoses.

Another modern fungus-related health problem is an allergic respiratory condition brought on by inhaling mould spores. Mouldy buildings are one source, and are a serious health risk to sufferers.

The vital natural processes of rot and decay do not stop at your front door. In fact your front door and any other wood used in construction is also liable to attract saprobe fungi. Just provide a few damp areas with poor ventilation and watch them set to work!

One recent addition to this rogue's gallery of fungi is a microorganism of the genus Batrachochytrium. In recent years it has been killing frogs and other amphibians around the world. Biologists suspect that changing environmental conditions may have impaired amphibian immune systems , leaving the creatures vulnerable to fungal attack.
 
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