Botanical Name: Eucalyptus globulus
Most people readily recognize the scent of eucalyptus, but many don’t realize that this evergreen tree also has a wide variety of uses. Koala bears typically come to mind when thinking about eucalyptus, although it is used by humans as well. The most common type of eucalyptus, known as the Blue Gum tree, grows primarily in Australia and Tasmania, although there are over 300 known variations of the plant. The leaves and leaf oil of the eucalyptus tree are typically utilized for medicinal purposes, and it is not uncommon to find eucalyptus in a number of over-the-counter drugs, cleaners and even air fresheners. Eucalyptus can be found in a number of forms.
Forms of Eucalyptus
Leaves – In both fresh and dried form, leaves of eucalyptus are used as air fresheners and in medicinal teas.
- Oil – In this form, eucalyptus is added to cough and cold medicines, dental products, antiseptics and used directly to treat fevers. Oils are also used in industrial mining operations and as aromatherapy.
- Ointment – Applied directly to the skin, the plant is used for treating minor aches and pains. It is also an ingredient in several over-the-counter rubs to be used as cold treatments.
- Sprays – Some companies sell the plant in a spray form, allowing it to be used topically on humans and pets.
At one time, eucalyptus was thought to be a valuable treatment for diabetes. Although it does appear to cause fluctuations in blood sugar levels, research continues regarding the exact benefits, if any, for diabetics. Other documented medicinal and healthy uses for eucalyptus include:
- Treatment of respiratory illnesses – Coughs, colds, sore throats, asthma, and congestion appear to respond to medicines containing eucalyptus. Relieve congestion and cough by rubbing eucalyptus oil or ointment into the chest. Another method for relieving congestion and other respiratory problems involves boiling eucalyptus leaves in a tightly covered pot filled with water then removing the pot from heat to inhale the vapors. The plant’s oil can be mixed with warm water to create a mouth rinse that helps alleviate sore throats. As an antibacterial, natural decongestant, eucalyptus often reduces the intensity and the duration of respiratory illnesses.
- Burns, cuts and insect bites – Topically, eucalyptus may be used as an antiseptic reducing the risk of infection and promoting healing.
- Muscle and joint pains – Rubbing oil from the leaves into the muscles and joints has been known to temporarily relieve pain. Below is a recipe for making your own relaxation massage oil that is great for a soothing massage:
- Reducing fevers – A small amount of the oil taken internally may temporarily reduce a fever.
- Stimulant and stress reliever – Eucalyptus leaves and oil provide an aroma that can be useful in dealing with stress and fatigue.
- Dental care – Eucalyptus oils may be found in mouthwashes and toothpastes because it’s a natural bacteria fighter.
- Bug repellant – In both Honduras and Venezuela, the plant is used to keep bugs away.
- Parasite deterrent – Guatemalans use eucalyptus to get rid of ringworm and topical parasites.
Climate and Soil:
The plant is sensitive to severe frost and excessive drought. It tolerates rainfall upto 400 cm but can be grown in places receiving rainfall from 200 to 300 cm annually. E-globulus can grow well above 2000 m MSL but E.citriodora grows well from 1500 to 2000 m MSL. Higher the altitude, better is the quality of the oil. It can be grown in acidic soil, rich in organic matter, with good drainage.
Eucalyptus is propagated by seed. As the root system is sensitive to transplanting, the seeds are directly raised in polythene bags of 22 cm x 16cm size. The containers are filled with pulverised shola soils. Two seeds are sown in each bag and the right time of sowing is January/February under South Indian conditions. The polybags are staked in the nurseries and partial shade is provided. The seeds normally take 10-15 days for germination and they attain plantable size within 2 to 3 ½ months from sowing or when the plants have produced 5 to 6 true leaves.
The land is cleared of the vegetation and pits 30 x 30 x 45cm size are dug at spacing of 2m x 2m. The pits are then allowed to wither before planting. The pits are filled with topsoil after adding 30g of rock phosphate per pit. Right planting season is the commencement of South West monsoon and while planting, polythene bags are completely removed and planted without damaging the root system. Staking the plants to permit the wind damage is desirable. Gap filling is done until two years to ensure proper population in the field.
Manures & Fertilizers
The Cinchona department in Tamil Nadu recommends 200g per plant a fertilizer mixture of Nitrogen, Phosphorus and Potash at 25: 38: 38. This fertilizer mixture is applied by pricking the soil to a depth of 8 cm during the end of monsoon season.
Harvesting & Distillation
In E.citriodoro, harvesting consists of pruning and collecting the terminal branchlets and leaves upto three years. In the Fourth year, coppicing the main stem is done 5cm above the stem portion having lignin. The coppicing cycle is adopted for every fourth year and the leaves are collected for distillation. Recently, it has been reported that instead of harvesting at the end of coppicing cycle, harvesting the leaves at periodic intervals (6-12 months) results in higher leaf yield with higher citronellal content.
Another method of harvesting involves pollarding the main stem at a height of 3m and the leaves are regularly collected for distillation from the shoots that emerge from the pruned stems. Best time for harvest of the leaves is March-May as the leaves have high oil content at that time. In Wynad area, harvesting twice i.e. premonsoon period (May) and post monsoon (November) is recommended. The harvested leaves are dried in shade for one day and distilled. Steam distillation is preferred to other types of distillation. On an average, the leaves yield 1.0% oil. The oil is a rich source of citronellal (70 to 80%).
In the case of E-globulus leaves are collected from the trees by cutting the side twigs twice or thrice in a year or the fallen leaves are collected from the plantations for distillation. When the plantation is felled for pulp wood purpose also, available leaves will be collected for distillation. The leaves are distilled high throughout the year but the most favourable time for distillation is from April to September, because of the yield of oil and cineole content during this period.
The collected leaves are dried in shade for three days and then subjected to steam distillation. Distillation per charge takes 5 to 7 hours. The yield of essential oil ranges from 0.75 to 1.25 percent. As the crude oil is wet, coloured and contain lower aliphatic aldehydes of unwanted odours, it has to be rectified or purified. This rectification involves the treating the oil over anhydrous sodium sulphate and distilling over 1 to 2% caustic soda. The cineole content varies from 75 to 85%. The rectified oil is colourless and has an aromatic camphoroceous odour.