Sugar cane is a grass and a member of the large botanical family that includes wheat, maize, rye and sorghum. While these grasses are grown for their seeds, sugar cane is prized for its stem. A giant grass with a unique destiny!
A noble family
Standing more or less upright, sugar cane has a thick, waxy smooth surface. Its colour ranges from yellow to purple, depending on the species. Divided into “nodes” every 10 to 20 cm, the cane is topped by a silvery, open-branched panicle that produces flowers. It can grow 5 metres tall and 3 to 6 cm in diameter.
There are two main types of sugar cane: wild and cultivated. Wild sugar cane is more hardy and woody, and grows better shoots, while the more substantial cultivated sugar cane is a hybrid of several varieties and richer in sugar.
Sensitive to the cold
Sugar cane loves warm, humid environments. It is the perfect example of a tropical plant. The ideal conditions for growing sugar cane is between 35° latitude north and 30° latitude south. The major sugar cane producing countries – Brazil, India, Cuba, Australia, China, Mexico, the Philippines, South Africa, Thailand and the United States – are located in this zone. In Europe, sugar cane is grown in Madeira and southern Spain.
Vigorous but demanding
Sugar cane is a perennial plant and spontaneously produces shoots after cutting. But it ages and needs to be replaced after four to seven years. Once the old stumps have been removed, the drills are prepared for the cuttings (parts of the sugar cane stem measuring approximately 30 cm with three buds or “eyes”), which are covered with earth.
The first shoots appear very quickly, but the cane takes one year to reach its flowering cycle. This period lasts two to three months. Once the plant has flowered, it has reached the final growing stage. The plant is now mature. This is the starting point for photosynthesis. Supported by a combination of dry weather and cool nights, photosynthesis leads to the formation of sucrose. Sucrose is spread unequally through the stem. The top is called the “white end” and contains the least sucrose.
The harvest
Sugar cane reaches maturity in eight (in Louisiana) to 22 months (in Hawaii). The viability of sugar cane as a crop depends on the climate, soil, irrigation, the variety, and the effectiveness of measures taken against diseases and parasites. The harvest can stretch over several months (from February to June in the French West Indies, and September to November in the Reunion Islands). The stems are cut as close to the ground as possible before being cropped.
Except in underdeveloped countries, where this work is still done by hand, sugar cane is cut and gathered by machines (chopper-harvester, cutter-loader and loader-grappler). Once cut, sugar cane begins to lose its sugar content very quickly. Trucks and tractors remove it to the processing plant immediately. The sugar cane must be processed within 12 to 36 hours after cutting. The average yield varies between 60 to 100 tonnes per hectare. A tonne of sugar cane is roughly equal to 115 kg of sugar. There are two sugar cane growing regions on French territory – the French West Indies and the Reunion Islands.
Cane parasites
Sugar cane is vulnerable to numerous harmful insects, including white grub, aphids, cochineals, and especially “borers” that sap the plant’s resources. Producers use biological controls (parasitic insects that kill borer larvae), chemical treatments (pesticides) and genetic modification (development of varieties resistant to parasites) to combat the insects.
Rats also cause a significant amount of harm. he spreading of poisoned seeds and the use of anticoagulant baits are two ways of combating rodents. Eelworms, which are mainly found in sandy soils, and termites also pose a threat to harvests.
Cane diseases
Sugar cane is at risk from three types of diseases. Some diseases are caused by a fungus, such as mildew, smut, red rot or rust. Others are spread by bacteria (gummosis, scald, and feeding on primary buds). Viruses can also damage cane crops. They include mosaic disease, Fiji disease and chlorotic streak virus.
New varieties of sugar cane have been developed in response to these problems. Other efforts, such as quarantine and knife disinfection, can be undertaken to avoid or slow the spread of disease. Chemical products and heat can be used to protect and heal cuttings. Finally, sanitary purification of nurseries and fields may be performed, if necessary.