In 1890, Sri Lanka, once the world's leading coffee grower, was plunged into an unprecedented crisis. A 15-year-old rust has reduced Sri Lankan coffee production to one-twentieth of its original level. To make matters worse, although the British colonial government sent excellent plant pathologists, the technical conditions at that time still could not solve the coffee rust. Faced with a coffee plantation that was almost destroyed by rust, the desperate plantation owner finally chose to give up. Infected coffee trees were destroyed, and tea trees that grew in a similar environment were used to fill the land. This change has had a huge impact on British society. Britain's "national drink" changed from coffee to tea, and tea culture began to prevail in British society. Eventually, the British began to use the phrase "my cup of tea" to refer to something they liked. What is not well known is that, in addition to the introduction of tea, Sri Lankan coffee growers also introduced another cash crop, the rubber tree, which later influenced history.
< h1 class="pgc-h-arrow-right" > rubber hometown in South America</h1>
There are more than 12,000 species of plants in nature that produce latex. In other words, all these plants produce rubber. But there is only one tree species that can be used for large-scale rubber production – the three-leaf rubber tree. It produces latex with a rubber content of up to 50%, ranking among the best in all latex plants. In addition, the three-leaf rubber tree has a long lifespan and can be used for rubber production for up to 30 or 40 years. These advantages make the rubber tree almost the only source of natural rubber.
Although the production capacity of the three-leaf rubber tree is outstanding, it is quite picky about its growth environment, which greatly limits the planting area and planting area of the three-leaf tree. Clover prefers a warm, humid environment. When the temperature is lower than 10 ° C, the growth of rubber trees is severely inhibited. Once a frost occurs, the rubber tree will die quickly. Therefore, the three-leaf rubber tree can only live in warm areas with an average temperature between 20 and 30 ° C. In addition, due to the huge canopy but the branches are not strong, the wind resistance is poor, so the planting area can not have strong windy weather. Lands that meet these conditions are concentrated in low-latitude tropical or subtropical regions.
Compared with artificial rubber trees, wild rubber trees have a more limited distribution area. Most of the world's wild clover trees grow in the Amazon rainforests of South America, with Brazil being the largest of them. Therefore, the three-leaf rubber tree is also known as the Brazilian rubber tree.
<h1 class= "pgc-h-arrow-right" > "black gold" in the jungle</h1>
The use of natural rubber has a long history, dating back to 1600 BC. Archaeologists have found that the Olmecs living in Central America at the time were already using natural rubber to make rubber balls for recreation and sports. Since there were no three-leaf rubber trees in Central America, the rubber used by the Olmecs came from the latex of elastic Cassan wood, known as the Panamanian rubber tree. Unlike the Olmecs, the indigenous peoples of the Amazon rainforest used rubber more practically. They treated clothes with rubber to make them waterproof.
Although primitive tribes began to use rubber very early, the great value of rubber that human society really discovered was due to explorers from Europe. In 1736, the French explorer La condamine brought back to France the natural rubber of the Amazon rainforest. Over the next few decades, scientists did a lot of research on the new material. At the same time, the industry also has a strong interest in rubber. Since people did not have the ability to produce plastics or other synthetic materials at that time, natural rubber became the most ideal waterproof material due to its advantages of elasticity, plasticity, lightness and waterproofness. The main use of early natural rubber was to make a variety of raincoats, boots and raincoats.
In 1844, the American inventor Goodyear invented rubber vulcanization technology, which greatly improved the resistance of rubber to temperature changes and completely overcame the stubborn diseases of hardening on cold days and softening on hot days of natural rubber products.
Vulcanization technology makes rubber a truly practical industrial product. In the 30 years since the invention of this technology, industrial demand for natural rubber has increased more than 100 times. In 1888, the Englishman Dunlop invented the world's first pneumatic tire. Subsequently, rubber pneumatic tires became standard in the car. In the 20th century, with the rapid development of the automobile industry, the output of rubber tires continued to increase, and the demand for natural rubber also increased significantly. People even call it "black gold".
With the rising value of natural rubber, latex collection has become a lucrative industry. Countless people rush into the Amazon jungle with the dream of getting rich, trying to find a "black gold mine" that can make them rich.
<h1 class="pgc-h-arrow-right" > shift from west to east</h1>
In the early days of the rubber industry, all rubber was extracted from the latex produced by rubber trees.
First, the rubber pickers use an axe to cut a hole in the rubber tree and collect the latex from the opening. Although this "hole opening method" does not kill the rubber tree immediately, and the latex can be collected repeatedly, it will greatly shorten the life of the rubber tree, and the rubber tree is often cut down several times and dies. Backward production models are quickly swallowing up rubber trees in the rainforest, but the demand for rubber in the industry is growing. So I began to try to plant rubber trees.
Artificial rubber trees have obvious advantages over natural rubber trees. For example, the natural growth of three-leaf rubber trees in tropical rainforests is very sparse, with about two trees per hectare, and rubber pickers spend a lot of time on the road; while artificial rubber forests can be planted at a density of 600 trees per hectare, and the dense distribution improves the speed of rubber picking and facilitates the care of rubber trees. After tasting the sweetness, the scale of rubber cultivation in South America continued to expand. In the 10 years since the end of World War I, south American rubber cultivation has reached an all-time high. American auto giant Henry Ford alone has more than 3,000 hectares of rubber forest in Brazil.
With the development of artificial planting technology, rubber trees not only went out of the rainforest, but also began to go out of South America. In 1876, the Englishman Wickham quietly shipped 70,000 rubber tree seeds out of Brazil and to Britain. Wickham's move completely changed the production pattern of the rubber industry, and rubber trees were passed from the western hemisphere to the eastern hemisphere.
As the UK's natural environment and climatic conditions are not suitable for rubber trees, the first foothold of these 70,000 seeds is the greenhouse of the Royal Botanic Gardens. Under the careful care of the artificial environment, more than 2,300 seeds sprouted and grew into rubber saplings. The British then sent the seedlings to their Asian colonies of Sri Lanka and Malaysia. Malaysia and Sri Lanka, also known as Ceylon at the time, part of the land is close to the equator, where the climate is similar to that of the Amazon jungle region, and the soil conditions are suitable for the growth of rubber clover trees. Although most of the saplings died during long sea voyages, the hundreds of surviving seedlings grew well in both countries, gradually spreading to rubber plantations and to neighboring countries. The first trefolia rubber tree in China was introduced from Singapore in 1904, when Singapore also belonged to Malaysia.
< h1 class= "pgc-h-arrow-right" > the demise of the rubber kingdom</h1>
Rubber trees have taken root in Sri Lanka and Malaysia, and with coffee-centric farming in both countries, people don't realize the tremendous value of rubber trees. It wasn't until the 1890s that rust destroyed the coffee farming industry in these areas. In order to fill this gap, the rubber plantation industry has embarked on the road of rapid development. By 1907, sri lanka and Malaysia had planted more than 300,000 hectares of rubber trees.
In addition to seizing the opportunities brought by rust, the efforts of scientists have also provided a strong impetus for the development of the industry. Among them, the British scientist Ridley, who was the director of the Singapore Botanical Gardens at the time, contributed the most. His continuous tapping method is a milestone in the history of the rubber industry.
There is a tissue in the rubber tree that resembles the mammary glands of animals called "milk ducts". Responsible for the production and storage of latex. When the latex tube is opened by an external force, the internal pressure pushes the latex out. Since most of the latex tubes are located in the bark, the picker only needs to cut the bark and the latex will flow out of the wound. Unlike the "axe method", ridley's cutting method only requires a shallow incision in the bark, does not touch the formation layer, can collect latex, and will not seriously affect the health of the rubber tree. As a result, the validity period of rubber trees has been extended from years to decades. After the adoption of the rubber tapping method, the production efficiency of the Asian rubber industry has been greatly improved, making South America far behind, and Asian countries have begun to occupy the leading position of the world rubber industry.
What ultimately destroyed the Rubber Industry in South America was a disease. In 1905, a rubber tree disease appeared in the Panamanian rubber plantation, named "South American leaf blight". In the decades that followed, the "South American leaf blight" ravaged Central America and spread to Brazil in 1930. "South American leaf blight" is caused by a fungus called leaf blight. This fungus prefers to infect the young parts of rubber trees, especially the young leaves. A large number of rubber leaves infected by leaf blight die and fall off, which seriously damages the vitality and production capacity of rubber trees.
The devastating South American leaf blight is not a new disease. It has existed in nature for a long time, but has never been popular on a large scale. This is because South American leaf blight relies on spores to spread between trees, and its spore size is relatively large and is not easily transmitted by the wind. In nature, the spores of South American leaf blight are often washed away by rainwater on diseased leaves and then spread to animals through the flow or pollution of rainwater. In the rainforest, rubber trees are sparsely distributed, and the distance between trees is very large. Rain and animal transmission are difficult to break through this spatial barrier. In plantations, however, the situation is very different. The rubber trees are very close to each other. Water splashed on rubber tree leaves can easily transfer spores from one tree to another. This convenient route of transmission makes it impossible for rubber plantations to become uncontrollable once the disease occurs.
Faced with rampant disease, Brazilian rubber planters have had to repeatedly spray fungicides to protect rubber trees from South American leaf blight. However, the cost burden of heavy use of biocides further weakens the competitiveness of the Brazilian rubber industry. Scientists are also trying to develop South American leaf blight-resistant varieties. However, they were disappointed to find that varieties with good disease resistance tended to have poor gum production capacity, while high-yielding varieties were sensitive to leaf blight in South America. Some scientists have found that the production of rubber tree latex mainly depends on the trunk, and the main site of infection of south American leaf blight is the crown of the leaf. So they used the method of artificial grafting, combining the trunks of high-yield species with the crowns of disease-resistant varieties. This combination of complementary advantages can achieve both high yields and disease resistance; however, the cost of grafting is also unbearable for rubber growers.
Brazil's rubber industry is shrinking under the onslaught of leaf blight in South America. By 1940, Brazil's rubber production accounted for only 1.3% of the world's rubber production. The rubber kingdom of the past has completely fallen.
Today, the shadow of leaf blight in South America has not disappeared. Rubber plantations in Southeast Asia and South Asia are very monolithic. They are basically the descendants of hundreds of rubber seedlings brought by the British more than 100 years ago. These varieties are not highly resistant to leaf blight. Rubber trees concentrated in some areas even stretch for hundreds of kilometers, creating conditions for the epidemic of leaf blight. If someone intentionally or unintentionally brings pathogenic spores into plantations, it could lead to a repeat of the tragedy in South America and have a serious impact on the world rubber industry. How to avoid risks and win the fight against south American leaf blight is a difficult problem facing scientists.