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The history of fungicide - A case study of Rust

Spring is the time when what we harvest in autumn is determined.  Planting is half the game, tending is the other.  Good forethought in both allows success.  For those of us planting wheat and other small grains this year, we should not fear rust – the war against rust has already been won.

A good place to start is with the god of war.  Incidentally, March is named after the Roman god of war, Mars.  But most people don’t realize that this fearsome god also was the guardian of farms and ranches!  March was an ideal time to begin war and begin the new agricultural season, and his festivals were celebrated in this month.

While his Greek counterpart, Ares, is similar in many ways, Mars is quite a different fellow.  He was venerated as part of an ancient trinity of Jupiter and Quirinus.

Quirinus, less known to our modern Greek-oriented society, had no Greek counterpart and was the god of the State, the spearholder, Janus.  Quirinus was the Sabine god of war, and later became the deified Romulus, and his priests were venerated for being able to prevent rust in crops by sacrificing puppies.  In the last days of Rome, the Roman trinity no longer was Jupiter, Mars and Quirinus, it was Juno, Minerva and Jupiter.  During these last days before Christian Rome, the Quirinus was worshiped only by his Priests, who, after turning over their rust protection job to the Priests of Mars, were content to have the only function in Roman society as proceeding the Pontifex Maximus (a title that literally means “Great Bridge Maker,” or the connection between the world of the gods and our human world).  During Christian Rome, the title was assumed by the Pope, who didn’t have much need for Quirinus, or the ancient roman trinity.  But I digress.

Mars was born out of jealousy.  Juno, jealous of how Zeus gave birth to Minerva after a really bad headache (when Minerva came out of his forehead, he felt better), Juno wanted to do the same.  Not the headache, but the self-propagation.  Flora, the goddess of spring, was consulted and prescribed a particular flower.  Dubious about experimental drugs, Juno tested the herb on a cow, who gave birth at once (PETA had not been invented yet).  Juno then took the drug and, after retiring to Thrace, gave birth to Mars.  For the brief time of the Romans, women looked to Juno for help in easy childbirth.  And Flora for conception. 

Mars was very much loved by Venus, but he loved Nerio, the goddess of Valor.  Nerio was originally a female version of Mars, but for whatever reason the Sabines decided that one god of war was better than two.  It seemed to work for them.  Mars was represented by both the woodpecker and the wolf.  Mars was one of the few Roman gods to be clean shaven – from head to toe.  When Julius Ceasar shaved himself all over, it was not just for cleanliness, it was to emulate and perhaps personify the god…a frightening tactic in ancient Rome!  When Mars was victorious, Nerio would decorate his spear with flowers or other vegetation.

His priests had several functions in ancient Rome.  They would leap and dance in full armor before war to gain the god’s favor, they would bless treaties and ask Mars to keep peace, they would supervise other Priests to make sure that all the ceremonies were done properly (securing the treaties with heaven – the Romans made deals with the gods, that if they did rituals in such and such a way, the gods would fulfill their promises to love them).  But they also sanctified farms and ranches.  Mars became associated with the supreme gods of all those whom the Romans conquered, and earned new responsibilities along the way. 

The god seems to be retired now, but his Priests are not available for comment.  Sacrificing puppies hasn’t worked for some time in warding off rust.  And many treaties have been broken.  Rumors disagree.  Perhaps he is happily retired, raising cattle, pigs and sheep with his wife, Nerio.  Perhaps he’s gotten into goats.  In any case, his wheat fields are as beautiful as ever, always free of rust.

Preventing rust begins with good soil maintenance.  Tilling in the aisles to maintain biodiversity of microorganisms and maintaining biodiversity of macroorganisms in the field is a great start.  But rust thrives where there is insufficient evaporation of excess moisture. 

Jethro Tull, the first scientific farmer, reviewed the work of his predecessors with disappointment in his Horse Hoeing Husbandry.

“The Ancients did not take notice that there were several kinds of blight, neither did they inquire after their causes.  This lack of curiosity and observation prevented them from learning their causes and developing effective remedies against blight.  They called it in general by the name of “rubigo” or “rust” for the likeness of the blighted straws and leaves to the color of rusty iron.  They thought it came from the gods since they were ignorant of the natural causes.  Virgil, who was very sincere when he had no hopes of great gain by flattery, tells the common farmer in plain terms that if his grain is eaten with the blight, that there is no better advice than to comfort their hunger with wild acorns. 

Virgil was a cheery, helpful and hopeful fellow. 

But the optimism of Virgil aside, Palladius at least contrived to, as Tull explains, “conjure sympathies and antipathies with the clouds.  And when prayers and sacrifices would not prevail with the clouds, the ancients proceeded to threats to scare them.  They brandished bloody axes against the gods  as a summons to surrender or expect no quarter, but unless these peasants had better means than the Titans  in besieging heaven, it may be believed that their menaces were in vain.  Palladius thought, as many of the ancients did, that Heaven was to be frightened from spoiling the fruits of the field and garden with red cloth, the feathers or the heart of an owl, and a multitude of ridiculous scare crows.  The ancients, having no rational, logical, scientific principles of agriculture, placed their chief confidence in magical charms and enchantments .  Those who have the curiosity and patience may read of them in Virgil, Cato, Varro and even Columella (as fulsome as any of them!), all written in very fine language (which, I freely admit, is not all the erudition that can be acquired from the Greek and Latin writers of agriculture in verse and prose). 

So, what is a modern farmer to do, if threatening atmospheric water vapor with axes doesn’t work, and they happen to be sort on red cloth, or can’t find owl heart at the supermarket, and you’re not inclined to slaughter your puppy?  Where does rust come from when all the gods are asleep in their marble ruins?

In our modern day, it is easy for a farmer to hop onto Wikipedia and learn that “Wheat leaf rust, is fungal disease that effects wheat, barley and rye stems, leaves and grains. In temperate zones it is destructive on winter wheat because the pathogen overwinters. Infections can lead up to 20% yield loss - exacerbated by dying leaves which fertilize the fungus. The pathogen is Puccinia rust fungus. Puccinia triticina causes 'black rust', P.recondita causes 'brown rust' and P.sriiformis causes 'Yellow rust'. It is the most prevalent of all the wheat rust diseases, occurring in most wheat growing regions. It causes serious epidemics in North America, Mexico and South America and is a devastating seasonal disease in India. All three types of Puccinia are heteroecious requiring two distinct and distantly related hosts (alternate hosts). Rust and the similar smut are members of the class Teliomycetes but rust is not normally a black powdery mass.”  Understanding (or not) about fungus diseases, an antibiotic is available, or if not, precautions can be taken to reduce fungus in the field.

There are plenty of natural and artificial fungicides (not one of them is made out of the intestines of a puppy sacrificed in March, though).  But we need not bother with them.  Nearly 300 years before Wikipedia was a dream, Jethro Tull discovered the source and solution to rust.

By understanding that the problem arose when too much moisture was on the field, he sought to reduce field moisture through wind and sun powered evaporation.

Air, being a fluid, moves most freely in a straight line.  A straight line offers the least resistance to its parts: a straight river runs swifter than a crooked one (at equal declivity) because less of the water strikes against the banks at turnings.  The banks slow the river.

          The air cannot pass through broadcasted wheat in a direct line because it must strike against and go around every plant (they stand all the way in its course and stop the current near the earth).  The air in the broadcasted corn (like water amid the reeds on the banks of a river) is stopped in its course so that it becomes an eddy.  And, since air is more than 800 times lighter than water, we may suppose its current is more easily retarded – especially near the earth where the wheat has the occasion for the most air to pass (for though the upper part of the wheat is not able to stop a flow of current of air, it can hinder it from reaching the stalks.  Thus the air around the stalks in broadcasted wheat remains stagnant).  The thicker the wheat is – where it stands promiscuously – the less the air circulates.  The greater the number of stalks, the more air they require.

          But the confused manner in which the plants of broadcasted what stand is such that they must all oppose the free entrance of air amongst them (from whatever point of the compass they come).  Now, it is quite otherwise with wheat that is drilled regularly with wide aisles .  Through the aisles the wind can pass as freely as water in a straight river where there is no resistance and communicate its fertilizer  to the lower (as well as) upper leaves.  The air can carry off the wastes the plants emit and will not suffer the plants to be weakened (as animals are when their lungs are forced to take back their own expirations and debarred from a sufficient supply of fresh untainted air).  The benefit of fresh air is plentifully and pretty equally distributed to every row in a field of hoed wheat with wide aisles.

Tilling in the aisles, besides improving root density, increasing soil fertility and improving the health of the roots, also improves the health of the leaves and above-ground parts of the plants as well. 

This spring, plant your grains in beds and aisles, and you won’t have much reason to fear rust.


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