Living with parasites

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			Living with parasites The history of tobacco is counted in tens of thousands of years, and over this time, it has learned to cope with bad weather conditions, diseases and pests. Though to be fair – not without a little help from man. In this article, Willy Alvero, general representative of Habanos S.A. in Russia, describes how tobacco experts help the plant to survive against parasites. Tobacco of the variety nicotiana tabacum, from which cigars are made, is an agricultural crop. Unlike wild tobaccos, it has slenderer leavers and excellent organoleptic characteristics. But it also has its disadvantages – it cannot exist without human support. Left to itself, this variety would either mix with other, stronger strains or simply die out. Scientists have shown that nicotiana tabacum appeared in the Bolivian Andes as the result of an accidental crossing of wild tobacco varieties. The aboriginal Indians were attracted by its unusual appearance and the exceptionally pleasant aroma of some of its bushes. And so attracted were they, that they transplanted these bushes nearer to their dwellings. Had it not been for the Indians, the nicotiana tabacum variety would have long disappeared from the face of the earth. This hybrid plant would have been too weak to survive the process of natural selection. Botanists call varieties of this kind ‘intermediate’ – that is to say that left to themselves in nature, they are not viable and perish as suddenly as they first appear. To last, they need ideal conditions, which only man can create. Modern tobaccos of the nicotiana tabacum variety, which are grown in Cuba and the other tobacco-growing countries, are not much different from the tobacco plants found by the Indians in the Bolivian Andes. And they are just as delicate and have just as many enemies – pests, diseases and bad weather conditions – as they always have had. Insects It is well known that pesticides, insecticides and chemical fertilizers do nothing to improve the gustatory and aromatic characteristics of tobacco, and for this reason planters use them only in the most extreme cases. And if the situation is not critical, they prefer instead of chemicals to rely on their own hands and skills so as not to traumatize the tobacco. Pests continually threaten the plantations, so methodical and painstaking work to detect and destroy them has long been the daily task of the tobacco-grower. The nicotiana tabacum variety is an annual plant and belongs to the nightshade (solanaceae) family. The plant has small, pink, flowers Many insects deposit their larvae in the ground. On a tobacco plantation, the larvae eat literally everything in their way and do enormous damage to the crops. The larvae of certain types of insect from the click beetle family (Elateridae) eat the tobacco roots and thereby stop the bush from getting the nutritious substances that are essential for life and growth with the result that the tobacco bush dies quickly. Tobacco-growers spend many hours examining the soil on their plantations and destroying any larvae found there. There is another and rather more unusual way of combating these pests. In the morning, a single boiled potato is buried in the earth beside each bush, and a stick put in the ground to show its exact location. The taste of the potato, rich as it is in starch, appeals much more to the larvae than the roots of the tobacco plant, and so they all head for the trap that has been prepared for them. In the evening, the tobacco-grower returns and pulls up the potatoes together with the pests. This sounds like an amusing tale, but it really does happen, and tobacco-growers can save their crops with the aid of a boiled potato. 0 The click beetle family (Elateridae) have characteristic antennae, which are generally serrate, but can be filiform or pectinate The Veronicella Floridana is a fairly large slug and another typical representative of the fauna found on tobacco plantations. Detecting it is, of course, much easier than detecting the larvae of the click beetle, since it feeds on the tobacco leaves and spends a lot of time on their surfaces. Thus, it is not difficult for plantation workers to make a daily examination of their bushes and clear them of these slow-moving slugs. The caterpillar of the noctuid moth (Heliothis virescens [Fabricius]), commonly known as the tobacco budworm is found in practically all countries where tobacco is grown, but only in Cuba is it dangerous for plantations. Tobacco-growers call this pest cogollero from the word cogollo – the topmost part of the bush, where the tiny leaves that have not yet opened resemble a bud, because this is where the tobacco budworm lays its eggs. The larvae, which hatch out four days later, at first start eating each other and continue their cannibalism until there is only one left in the bud. By the time the larva becomes a caterpillar, it’s already eating the fresh tobacco leaves. For a period of 26 to 30 days, the caterpillar gathers enough strength to leave the tobacco bush. Then it buries itself several centimetres into the ground and forms a cocoon, from which it emerges as a moth two to three weeks later. These night moths are well-known enemies of the farmer, and not only in Cuba – they also have a taste for plants found at Moscow suburban dachas The tobacco budworm has always been one of the worst problems for the Cuban tobacco-growers, since the leaves that it has eaten are completely useless for making quality cigars. Numerous ways have been suggested for dealing with it, but only one is really effective. A mixture is made of maize flour and a particular poison that is fatal to the budworm, but harmless to humans. This is then put on the tops of the tobacco bushes. The larvae make straight for the poisoned flour and soon die. Since the moth can lay its eggs on any day, the poisoned mixture must be applied regularly. Bearing in mind just how many tobacco bushes there are on a single plantation and also the fact that the job has to be done by hand, it’s easy to see what an enormous amount of work this involves. Weeds Apart from insect pests, the tobacco-grower also has to contend with various weeds and plant parasites. Not that there’s anything complex or unusual in this, and the tobacco-grower is in pretty much the same position as the gardener weeding out his tomato beds. But one exception is the parasitic plant known by the rather striking name of branched broomrape (Orobanche Ramosa Linnaeus). It attacks the roots of the tobacco bush and sucks out its water and nutrients. But the main danger lies in the fact that one branched broomrape plant produces up to 15,000 seeds that weigh a total of no more than 0.02 grams. And these seeds are carried by the wind and can live in the ground for several years. The main danger lies in the fact that one branched broomrape plant produces up to 15,000 seeds that weigh a total of no more than 0.02 grams. And these seeds are carried by the wind and can live in the ground for years Branched broomrape is widespread throughout the central regions of Cuba, where it seriously affects the harvests and the quality of the tobacco. Attempts to grow varieties that are immune to attack have not been successful, and it appears that Orobanche Ramosa Linnaeus can easily overcome even the wild tobacco varieties. But for all that, a solution has been found. Botanists have discovered that broomrape does not do serious damage if it appears on the roots of a tobacco bush that is already fairly well grown. It has also been discovered that the seeds of the parasite become active at approximately the same time each year – mid January. So now tobacco-growers plant a little earlier than the recommended time, so that by January, the tobacco bushes have already gathered strength and are able to withstand the branched broomrape. Tobacco Mosaic Virus In 1886 a group of Dutch botanists made a detailed description of a tobacco disease that had seriously plagued tobacco-growers in many countries. At first one bush would fall victim to the disease (and become covered with bright-green, irregular-shaped patches), then other plants would show similar symptoms, and finally within a short time it would have spread throughout a whole plantation. Not only the colour of the leaves was affected, but also their texture – they would start to swell and lose their juiciness. Ultimately, all the leaves became unsuitable for cigar making. Tobacco-growers had no means of saving their crops except by finding and destroying the infected bushes, and hoping against hope that neighbouring plants would remain healthy. This disease was called ‘tobacco mosaic virus’. In 1892 D.I. Ivanovsky, a Russian botanist, conducted a number of experiments on sick and healthy tobacco plants based on the findings of the Dutch scientists. His results proved conclusively the existence of a virus. It is easy to find the Tobacco Mosaic Virus – the leaf of infected plants speaks for itself Over the next forty years, the great majority of all experiments done in the field of virology were conducted on the basis of tobaccos. Finally in 1936, W. Smith isolated the tobacco mosaic virus in crystallized form from the sap of an infected tobacco bush. For this achievement, he was awarded the Nobel Prize in 1946, and the tobacco mosaic virus was given the name Nicotiana virus 1 Smith. Specialists tend to use the abbreviation TMV (Tobacco Mosaic Virus). The joint work of botanists and tobacco-growers did much to help understand the nature and characteristics of the tobacco-mosaic virus and what caused it to spread. It was transferred together with the sap of the infected plants, and even microscopic quantities were sufficient to infect a healthy bush. On the plantation, the infection was usually carried by insect pests or workers, who accidentally came into contact with the surface of an infected plant and continued working without disinfecting their hands. The incubation period for TMV was discovered to be three to four days from the moment of infection, after which the virus would begin rapidly reproducing. The most active reproduction would take place at a temperature of 26?29°C. Much other useful theoretical information was also gathered, but solving the problem in practice proved to be a far from easy task. No effective vaccine against TMV was found, and the virus continued to break out in Cuba and other countries. As is the case with many other infections, there has only been one solution to the problem – developing a new variety of tobacco that was immune to the virus. In 1959, work was begun at the Cuban experimental station in the town of San-Juan-y-Martinez. Obtaining a variety with immunity to TMV was not the only task facing the centre – apart from anything else, new varieties had to retain the excellent aromatic and gustatory characteristics of the original tobaccos. This objective was not achieved until the 1980s, when Escambray-70 became the first Cuban variety to possess immunity to TMV. Black Shank Powerful, aggressive and incredibly resistant fungoid parasites are dangerous for any plant. But when it is a matter of such a delicate crop as cigar tobacco, this danger is only increased. Fungoid parasites relate to a class of lower fungi and are basically nothing else but mould. For growth and reproduction, they require very particular conditions – moderate temperature, a minimum of sunlight and as much humidity as possible. The climate in Cuba during the tobacco-growing season is the complete opposite – hot, sunny and very little rain, so the lower fungoid organisms have never been common amongst the local flora. They first appeared on that Caribbean island in the early part of the 20th century as the result of certain unlikely circumstances occurring at the same time. The struggle against black shank (phytophthora rot) is waged by geneticists developing resistant tobacco varieties Black shank was the first of the fungoid varieties to make itself known. It is caused by Phytophthora parasitica var. nicotianae. The Cubans call it Pata Prieta. Lower fungi of this type are able to adapt easily to their surroundings, and they need only a few rainy days to propagate and produce spores. The spread of the infection was aided by the irrigation systems, since moist soil is a magnificent environment for black shank to flourish in. As a result, within a few years almost all the Cuban plantations were infected. Black shank attacks the plant at the base of its stalk, from where it spreads upwards. As the rot moves, the stalk of the tobacco bush acquires a characteristic dark colour, which is due to the gradual dying of the plant’s fibres. Stopping the spread of the fungus and controlling its propagation requires the use of special chemical compounds, called fungicides. But unfortunately, these do not just destroy the mould; they also ruin the quality of the tobacco and for this reason planters do not use them in the growing season. Fungicides are used for disinfecting the soil only in between seasons. But when the tobacco has been planted, the black shank can be activated by irrigation and occasional rainfall. Then it spreads and will damage the tobacco unless, of course, the latter possesses a special immunity. Unfortunately, the original Cuban Havanensis variety, with which practically all the plantations in Cuba without exception were planted at the beginning of the century, was particularly susceptible to black shank. The first varieties that were capable of resisting the pernicious power of this fungus – the Criollo y Corojo developed by Cuban scientists and the Pelo de Oro that came from Mexico – did not appear until the 1940s. Blue Mould Blue Mould (Moho Azul in Spanish) is what tobacco-growers call another simple fungoid type, known scientifically as peronospora tabacina. It was first discovered in 1906 by Wulf on the leaves of the wild tobacco plant, nicotiana Bigeloni, in Texas. But when he saw that the thin layer of bluish mildew did not appear to harm the plant, the scientist failed to give the proper attention to his discovery. After the First World War, blue mildew was again found on Texas tobacco plantations, but once again it appeared to do no damage to the crop, and once again it was soon forgotten. But meanwhile, the rivers and the wind continued the uninterrupted spread of peronospora tabacina throughout the United States, and each year the mould moved further and further south. The delicate nicotiana tabacum is susceptible to another type of fungus – blue mould A thorough study of this mould was not begun until the middle of the twentieth century. In 1941, Godfrey made the discovery that blue mould was only harmless to wild tobaccos; for the species nicotiana tabacum it represented a serious threat. However, the Cuban tobacco-growers were not worried, since they lived on an island with the sea all round them and thought that blue mould could never infect their plantations. Nevertheless, it did. In 1957 peronospora tabacina broke out in Cuba. It turned out that a strong wind could blow the spores for up to one hundred miles – and that is more than the distance between Florida and Cuba. But this time, the tobacco-growers on the whole had a lucky escape, since the blue mould only affected plantations in the Partido region. It did not spread to other regions and literally within a month it disappeared, having had no noticeable effect on the Cuban 1957 harvest. The general belief was that the new Cuban varieties that had recently been grown possessed a natural resistance to this infection. The words moho azul were not recalled again by the Cuban tobacco-growers until 1979 – when the blue mould once more reappeared on the ‘Island of Freedom’. But this time, it assumed epidemic proportions and destroyed more than 85% of the crop. Since then, blue mould has become endemic to the Cuban plantations, and today it can be found in every corner of the island without exception. The spores are mainly carried by the wind. When they land on a tobacco leaf, they penetrate through its pores and within a week become fungus. This fungus kills the cells, but does not show any particular activity. This starts when it comes to the surface of the lower side of the leaf where, protected by the sun’s rays, it begins rapid propagation. The lower side of the tobacco leaf becomes covered with greyish-violet patches – this is the peronospora tabacina or the blue mould. Lower types of fungi destroy only that part of the plant, with which they come into direct contact – the rest of the plant grows normally. But when you consider that tobacco leaves can grow at the rate of up to ten centimetres a day, it’s not hard to guess what happens to infected plants. A leaf that has been half infected with blue mould continues to grow, but ultimately curls up, if not to say twists up. Young plants – unlike the older ones – cannot withstand this kind of deformity and die at the root. But this is not the worst thing. Adult tobacco leaves can be deformed so much that they become completely unsuitable for cigar making. A plantation that has been infected with blue mould, gives off the steady odour of rot. But for blue mould to start producing spores after it has infected a plant requires very particular conditions. The day temperature should be approximately 21°C and the night temperature 10°C. Then the sky has to be covered with cloud and it should be raining. These conditions of high humidity make it possible for the spores to start forming. Then the wind picks up the spores and carries them to other plants and plantations. This all takes place very quickly – two to three days being sufficient for a blue mould epidemic to take hold. In one season, blue mould spread throughout the island of Cuba and became for Cuban tobacco-growers the same scourge that phylloxera had once been for French wine-growers. Specialists noted that moho azul did best of all on fertile soils, where it grew rapidly and produced the maximum number of spores. And since the soil of Cuba has no equal in the world, this made blue mould the worst problem that had faced the tobacco growers for many years. After the catastrophe of 1979, tobacco-growers had to use fungicides annually in a bid to get some control over the growth of the peronospora tabacina fungus. Henceforth, the presence of a single infected bush meant that the tobacco-grower had to burn the whole plantation, despite the fact that this entailed huge financial losses. But it did mean that there was no repetition of anything like the 1979 epidemic, though it was still not possible to eradicate blue mould completely, and the infection continued to appear on one or other of the plantations. But worse than this was the fact that moho azul was gradually beginning to adapt to the fungicides that were being used against it – and that could soon lead to a repeat of the epidemic. Cuban scientists working in plant selection faced a new task, and one that was probably the most complex in the whole history of tobacco growing. They had to produce a variety that possessed simultaneous resistance to three terrible diseases: blue mould, black shank and tobacco mosaic virus. Black shank was beaten back in the 1950s and work on resistance to TMV was already nearing completion. But the appearance of blue mould shuffled all the geneticists’ cards. Studies showed that the best resistance to the peronospora tabacina fungus was possessed by a variety of wild tobacco known as nicotiana Debneyii. This the scientists included in their work program, which was designed to ensure that, as a result of selection, the dominant resistant chromosome should become part of the genetic make-up of a new variety that would thus be immune to blue mould. In 1988 the Corojo and Criollo varieties were crossed with the wild nicotiana Debneyii to produce the Habana P.R. variety. This was the first tobacco that apart from its excellent organoleptic qualities possessed resistance to blue mould, black shank and tobacco mosaic virus. The subsequent development of the selection program resulted in the creation of the three varieties that are grown today and used in the making of fine Cuban cigars. These are the Habana-92, the Habana-2000, the Criollo-98 and the Corojo-99. Their unsurpassable gustatory and aromatic characteristics and their ability to resist practically all tobacco infections point to a high yield and are thus ideal for cultivation. Only the Cuban varieties can combat branched broomrape (Orobanche Ramosa Linnaeus) by themselves, and in this they are even better than the wild tobacco varieties. Scientists working in plant selection faced a new task, and one that was probably the most complex in the whole history of tobacco growing. The new varieties had to be able to resist three terrible diseases simultaneously. The tobacco beetle The tobacco beetle, an insect of the species lasioderma serricorne, lays its eggs in the tobacco leaves. Unlike other pests, the hatched larvae do not eat the tobacco leaves, but go into a kind of suspended animation. This happens because the larvae do not like the ordinary vegetable taste of the leaves. They reawaken when the tobacco is harvested and acquires, as the result of fermentation and maturing, rich gustatory and aromatic characteristics. As a result, it is the cigars and not the plants that fall victim to the pests. Once awakened, the tiny light-yellow larvae start eating the tobacco. This they continue doing for from 30 to 60 days, leaving long trails through the cigar. By the time they have eaten enough, the larvae have reached a length of about four millimetres. They then turn into a cocoon, from which the adult insect appears in about 9 to 20 days. In size, it is no longer than three millimetres, but it has a revolting appearance: its body is hunched and covered with hard, testaceous plates; its head is bent downwards; and its back is crowned with a ridge of sharp spikes. The adult lasioderma makes a hole to get out of the cigar and then hurries to find a mate for the purposes of reproduction. It can fly, but throughout its life it can’t cover more than three kilometres in the air. If it is unable to find a tobacco plantation, the lasioderma makes for ready-made cigars. This insect can easily bore a hole in a cigar box and even get into a metallic tube if there is the slightest crack in it, so strong are the testaceous plates on its body. The hunchbacked beetle, whose head consists of nothing by teeth, is the piranha of the insect world. Its larvae are dangerous both for tobacco leaves and for ready-made cigars The lasioderma is the enemy of the ready-made cigar. The fact that it can exist perfectly well a long way from the tobacco plantations means that it can regularly be found in tobacco warehouses, shops and cigar rooms around the world. It can easily get into a home humidor and in a short while ruin a collection, which a smoker has made over many years. Adult lasiodermae can survive at temperatures from 2 to 36°C, so even the cold Russian climate is not a problem to them. True, the insect cannot breed at a temperature lower than 20°C, so in winter Russian smokers can be more or less worry-free. But when the temperature reaches 30°C and the humidity – 78%, the lasioderma ceases to eat and drink, and does nothing but reproduce its own kind. Given a hot summer after rainfall, or the conditions of a humidor or a cigar room, nothing can hold it back. There need only be lasioderma larvae in one cigar to produce several adults, which will then reproduce and in a few months eat up the whole contents of a cigar box. A cigar that has played host to lasioderma larvae is impossible to smoke, because the smoke goes through the holes that they have made in it and will simply not draw. If you do try to smoke a cigar that has been infected with the larvae, the taste and aroma will contain an unpleasant protein tang – to put it simply, the taste of burnt meat. To check whether there are larvae inside a cigar, tap one end on a table. If there are larvae present, a dark powder will be shaken out of the cigar – the larvae faeces. There are numerous methods of protecting tobacco and cigars against lasioderma. Tobacco producers maintain cleanliness at the factories and clear away the clippings that could attract adult beetles. But this does not provide complete security. Before dispatching their products abroad, the Cubans put the loaded cigar boxes in hermetically sealed chambers, into which a cyanide-based gas is introduced. The gas is under pressure and so it penetrates every part of the box and every part of the cigars. The larvae perish and the gas is quickly dispersed – so cigars processed in this way are not dangerous to the smoker. Unfortunately, the lasiodermae – amazing as it may seem – appear to realize that they are in a gas chamber and try to lay their eggs in the veins of the tobacco leaves, where the gas cannot penetrate due to the thickness of the cigar veins – and so the larvae manage to survive. An effective means of combating the lasioderma and a good prophylactic measure is to freeze the cigars – at low temperatures the larvae and the eggs die. The cigars should be frozen at a temperature of -20°C for several days, and then defrosted by slowly raising the temperature. If this process is not hurried, the thawing cigar will not lose its fine external appearance, and the wrapper leaf will not show a sign of the freezing. Furthermore, specialists are of the opinion that freezing improves the draw of the cigars. To find out whether the pest has infected a cigar shop or a storehouse, special traps are set up that give off the odour of female lasioderma hormones. This attracts the males. If only one or two fall into the trap, there’s nothing to worry about. But if there are several insects, you can assume that somewhere they have been breeding and the number of the pests will inevitably increase. In this situation, it is essential to destroy their ‘hearth’ – the place, where the maximum number of adult beetles and larvae are concentrated. So as not to ruin all the cigars, several traps should be put around the room. Then, wherever the greatest number of insects appears, this will be near where the ‘hearth’ is located. There’s no point in getting too worried about lasioderma. The numbers of infected Cuban cigars that get to Russia are hundredths or even thousandths of a percent of the total volume of imports. This is to the credit of the people who are responsible for quality control and who combat the pest at all stages through which first the tobacco and then the cigars pass. The fact that tobacco today is grown safely and protected from pests, blue mould and other enemies is the result of long and painstaking labour. Instead of having their workers spend years in the laboratories developing new varieties or out in the blazing heat from sunrise to sunset removing weeds and pests, the plantations could simply be sprayed with chemicals. But then, the tobacco would lose the greater part of its amazing qualities, and we wouldn’t be able to enjoy its delicious taste. The highest quality cigars belong to the hecho a mano (handmade) category. It’s a shame that when we say these words, we think mainly about the method of rolling. It might also be a good idea to remember the work of the tobacco-growers. Prepared by ELDAR TUZMUKHAMEDOV