History of Eucalyptus Oil
The eucalyptus oil industry is an important and colourful part of Australia’s history.
It began in 1852 in Victoria and by the turn of the century it was well established and eucalyptus oil was being exported to many countries. Over the next 50 years this distinctively Australian industry was the major supplier of eucalyptus oil to world markets. However, since then Australia’s market share has fallen and production is now only five per cent of world requirements. Happily advances in science and technology have improved our competitive position and prospects are bright for Australia to regain lost export markets. The production of eucalyptus oil has the potential to be both an important rural industry and an interesting tourist attraction.
- The Market
- Main species presently exploited
- Land and Conservation
- Rectification and principal constituents
- Future Outlook
Eucalypts, which are evergreen, form about three-quarters of the tree flora of Australia. They are often called "gums" which is a misnomer as the exudation from the bark is not a "gum" but a tannin-like substance. Eucalyptus are typically Australian although a few species have been found in neighbouring countries. The extensive plantations in Africa, South and North America, Europe, India and China were planted with Australian seed.
Eucalyptus are widely distributed over the Australian continent. They range from the dwarfed and stunted forms called "Mallees" to the tall trees which grow in coastal and mountainous regions. More than 600 species have been described by botanists who have provided voluminous and conflicting literature on many of the species.
The eucalyptus are a valuable source of hardwood and although the leaves of all species contain some eucalyptus oil less than 20 have enough oil of commercial value to be exploited and of these only 10 account for almost the entire world production. As a general rule good timber producing eucalypts contain very little oil and those utilised for their oil are of little use as timber.
All eucalyptus oils are not the same. Each species produces an oil of different chemical composition and the constituents of one oil may be completely different from an oil from another species. However, eucalyptus oil from the same species is generally remarkably constant in its constituents and chemical composition.
The eucalyptus oils of commerce can be grouped according to their uses into three classes, viz. medicinal, industrial and perfumery oils. Perfumery oils account for only a small fraction of the total usage while medicinal and industrial oils are used in about equal proportions.
The eucalyptus oil industry is an important and colourful part of Australia’s history. It can probably claim the distinction of being the first truly Australian primary and secondary industry, as well as being Australia’s first export. Eucalyptus oil is one of the very few original contributions made to the commerce of the world by the discovery of Australia which is in sharp contrast to the wealth of contributions made by other continents.
The eucalyptus oil story began in 1788 with the arrival of the First Fleet and Surgeon-General John White. Within a few weeks of arriving, White recorded in his diary the presence of olfactory oil in the eucalyptus; the genus being named eucalyptus by the French botanist L’Heritier in the same year. Governor Philip sent a sample to Sir Joseph Banks. Surgeon-General White distilled a quart of oil from the "Sydney Peppermint", Eucalyptus piperita Sm., which was found growing on the shores of Port Jackson, where Sydney now stands.
When the oil was tested in England, it was reported to be "much more efficacious in removing all cholicky complaints than that of the oil obtained from the well known English peppermint, being less pungent and more aromatic". Following this discovery other people extracted eucalyptus oil, including the pioneer, Dr Officer in Tasmania, and the pastoralist Charles Armitage, but none of them exploited it.
Baron Ferdinand von Meuller, the Government Botanist in Victoria, encouraged Joseph Bosisto, a Victorian pharmacist, to investigate the essential oils of the eucalyptus on a commercial basis. Joseph Bosisto was a Yorkshireman who had qualified as a Pharmacist in Leeds and London. He arrived in Adelaide in 1848 at the age of 21. In 1851 he moved to Victoria in search of gold, but instead opened a pharmacy in Richmond, where he built a laboratory to investigate the chemical and medicinal properties of Australian plants.
As a result of the collaboration with von Meuller the essential oil industry of Australia began in 1852, when Bosisto commenced operations in a small, rudely constructed still at Dandenong Creek, Victoria, using the leaves of a form of E. radiata (then known as E. amygdalina) which grew profusely in the district. Bosisto soon built other distilleries at Emerald, Menzies Creek and Macclesfield.
Sales were to a restricted local market until overseas interest grew sufficiently for Bosisto to begin exports to England in 1865. Messrs. Alfred Felton and Frederick Grimwade saw the possibilities of the trade and their firm, Felton Grimwade & Co. became the distributors of Bosisto’s Oil of Eucalyptus which then was the only distinctively Australian substance in the British Pharmacopoeia.
To develop the new industry, Felton, Grimwade, Bosisto and others formed a new firm, the Eucalyptus Mallee Company and bought Antwerp Station - a property on the Wimmera River, near Dimboola, Victoria.
The low-growing Mallee eucalyptus were particularly suitable for cropping, but the area was remote and the company found unexpected difficulties from hungry rabbits and indolent aboriginal labourers. The enterprise was held up for some months by delays in the opening of the railway from Melbourne to Dimboola. By June 1882, 40 pounds of oil had been produced for export to England and Germany.
In 1885 the Antwerp Company was merged with Bosisto’s original business and a firm called J. Bosisto and Co. was formed. The new company was to be solely a manufacturer with Felton Grimwade and Co. undertaking distribution and all the necessary bookkeeping and marketing.
It is difficult to be certain which was the next species to be exploited as E. globulus, E. oleosa and E. cneorifolia were distilled for commercial purposes in the early 1880’s. Many farmers in Tasmania were distilling E. globulus at about the same time. E. cinerea was distilled in the Goulburn district of NSW between 1880 and 1900. There is no doubt that considerable interest was evinced in the exploitation of E. globulus, which ranked only second to E. amygdalina as a commercial oil-producing species.
Practically all of these species, with the exception of E. globulus, have been superseded by those giving larger yields of oil. The pioneer investigations of Baker and Smith showed that other species such as E. polybractea, E. australiana, and E. dives gave higher yields of oil of equal or better quality. It is from these latter species that the present-day Australian eucalyptus oils of commerce are produced.
The production of eucalyptus oil in the 1880’s was often carried out by aboriginals and by erstwhile miners as the goldfields petered out. It was hard work. The virgin scrub was cut by hand with slashers and special sickles. It was collected and carted by wagon to the distillery where the freshly cut leaves were dumped into vertical iron stills set into the ground below wagon level for easy filling. After steam had carried over the volatile oil the spent leaves were hoisted out by derrick and dumped on the fire whose rising column of smoke was a constant landmark.
The old distilleries were somehow kept going by pieces of wire, bits of tin, lumps of clay, and the infinite resourcefulness of the true bush workman, whose ramshackle buildings were made of hand hewn posts and roofed with branches of nearby trees.
Sales continued to increase with interest being fostered through international exhibitions. Between 1854 and 1891 Bosisto’s oil of eucalyptus was exhibited and was awarded prized in 17 international exhibitions. By the turn of the century oil was being exported to the United Kingdom, Germany, USA, Canada, South Africa, India, China, New Zealand and several countries in the Far East.
Sales were brisk following a lively promotion campaign. Bosisto’s produced an elaborate new label and a thousand circulars attesting to the powerful properties of oil of eucalyptus for "arts, manufactures, medicine and sanitary purposes" were distributed throughout the colonies and in Europe. In addition to the oil itself, Bosisto produced asthma cigarettes of eucalyptus globules which soon won some renown. These could be bought with or without tobacco. He also had a profitable line in Syrup of Red Gum for bowel complaints which he claimed was very soothing.
By 1900 Australia’s eucalyptus oil industry was well established and able to supply the world market with substantial quantities of various types of high grade oils.
However, it should be pointed out that from the very beginning oil production has been a very primitive business. Even today in a few areas the distillation of the foliage is still carried out in primitive stills set here and there in the mountains.
That the industry could develop and prosper until the Second World War is due greatly to one factor. Around the turn of the century the once rich gold fields in Victoria and New South Wales - the present producing regions of eucalyptus oils - started to run out and become unprofitable.
The gold miners found themselves without work. They had become used to the rough but free and independent life in the bush and consequently joined the eucalyptus distillers rather than seek employment in cities and towns. Things changed with World War II. The old class of distillers was gradually dying out and the younger generation would no longer accept the low wages and poor living conditions that had prevailed.
By about 1950 the cost of producing eucalyptus oil in Australia had increased so much that the oil could no longer compete against Spanish and Portuguese oils and Australia lost its leading position in the eucalyptus field.
Labour cost, however, was not the only cause of the decline. After the Second World War there was a strong demand for Australian wheat and this induced drastic destruction of stands of high quality eucalyptus species. Improved wheat strains and modern farming machinery allowed wheat to be grown successfully on land formerly suited only for eucalyptus. The class-conscious prosperous Australian wheat farmers have always been inclined to look upon oil production as a low grade occupation. Wheat growing appeared to be more profitable than eucalyptus oil production.
Australia dominated the world eucalyptus oil market for over 80 years. Regretfully Australia’s market share then declined to the point where Australia became a net importer of eucalyptus oil. Happily this trend is now being reversed, at least for medicinal oils. Advances in science and technology have been combined to modernise the industry.
By introducing mechanical harvesting and new distillation equipment the cost of production has been reduced greatly. This together with the natural advantages Australia has in having stands of eucalypts with high quality pharmaceutical oils has given the industry an opportunity to again become the dominant supplier in world trade.
It is impossible to obtain accurate information on the Australian or world production, sales and usage figures for eucalyptus oils. Even Australian import and export statistics can be misleading. The world consumption of eucalyptus oil is estimated to be about 3000 tonnes per annum. On today’s prices the ex-distillery value of this quantity of crude oil would be in excess of $15 million.
The total Australian annual production would be less than 150 tonnes and probably in the order of 125 tonnes for all types of oil. By way of contrast the total Australian production for the period 1939 - 48 has been estimated to average almost 1000 tonnes a year. It is therefore evident that the Australian industry has declined by about 85 per cent over the last 30 to 40 years. The position is even worse when it is remembered we once supplied 100 per cent of the world requirements whereas we now contribute only five per cent of the total. It would appear that we have almost managed to export the entire eucalyptus oil industry instead of retaining and developing this very Australian industry which is part of our heritage.
Because of inherent production advantages Australia should be in a position to increase export sales and earnings. In addition imports should be able to be kept at lower levels than have been recorded. However, the international market for eucalyptus oil is plagued with powerful market forces which are sometimes economic and sometimes political and therefore the future is always difficult to predict with any degree of accuracy.
Many countries which once imported eucalyptus oil now produce their own requirements. The major importing countries are the United States and the EEC countries. The major supplier of these markets is China. Much of the Chinese oil is not eucalyptus oil but a by product from camphor production. This oil is often called Chinese eucalyptus oil or eucalyptus oil (so called) even by our Bureau of Customs!
Strangely Australia is one of the few countries where small bottles of eucalyptus oil are sold to the public. Other countries where eucalyptus oil is sold as a finished product almost always use Australian eucalyptus oil. Most eucalyptus oil sold internationally is purchased as a raw material for use in manufactured goods.
It would appear that practically all buyers for manufacturers are more interested in the smell and colour of the oil rather than the constituents, chemical composition and product benefits that may be derived from a particular species of eucalypt providing the oil being purchased meets the general specification set down for eucalyptus oil.
The most important standard in the British Pharmacopoeia is that the oil must have a minimum cineole content of 70 per cent if it is to be of pharmaceutical quality. This has lead to the position whereby eucalyptus oil of dubious origin is often blended with cineole containing substances from any source to make a concoction that the buyers find acceptable as to cineole content, smell, colour, and price. Whether it is in the best interests of the industry is a matter of conjecture.
Eucalyptus polybractea commonly known as "Blue Mallee" is a small mallee type tree. It grows only in natural stands in the districts north and north-west of Bendigo in Victoria and in the West Wyalong area in New South Wales.
The yield of oil from the leaves and terminal branchlets varies between 1.5 and 2.5 per cent. Young material is richer in oil and the time of year also influences the yield.
The crude oil is high in cineole and usually assays at between 80 and 88 per cent. The absence of aliphatic aldehydes contributes to the pleasant aroma of the crude oil. The crude oil which is yellow to brown becomes a pale straw colour (rarely water white) on rectification. This high quality medicinal oil is now the principal pharmaceutical grade of eucalyptus oil sold in Australia and accounts for over one-half of the exports.
Eucalyptus radiata var. australiana, commonly known as "narrow-leaved Peppermint", is a medium sized tree with fibrous bark. It occurs in extensive areas in Victoria and the south coast districts and southern highlands of New South Wales. The yield of oil from the leaves and terminal branchlets averages between 3 and 3.5 per cent. The lowest yield, usually around 2.6 per cent is encountered during the winter months.
The crude oil has a cineole content of 65 - 70 per cent and because of the terpineol and citral constituents of the oil it has a very refreshing aroma. The crude oil is usually a very pale lemon colour but is colourless on rectification. Production of this pharmaceutical grade oil has fallen as the cost of production has become too high. The leaves cannot be mechanically harvested in the same way as E. polybractea because of the steep terrain of the natural stands.
Eucalyptus dives var. "C" belongs to the "broad-leaved Peppermint" group. It is botanically identical to E. dives (type) but the oils from these otherwise identical species have no resemblance whatsoever in chemical composition. However, the oil from E. dives var. "C" and E. australiana are practically identical in chemical and physical characters. The species grows in good stands in the Tumbarumba-Tumut-Batlow district of New South Wales.
The yield of oil from the leaves and terminal branchlets varies from two to four per cent and the oil is colourless. The oil is a good quality medicinal oil.
Eucalyptus dives (type) commonly known as the "broad-leaved Peppermint" grows along the coastal ranges of New South Wales and Victoria. Generally it is a moderate sized tree with a greyish-brown stringy bark.
The yield of oil from the leaves and terminal branchlets varies from two to four per cent with the general average being three per cent.
The oil of this species contains 1-piperitone (40 - 50 per cent) and phellandrene (20 - 30 per cent). The oil is used industrially for the manufacture of synthetic thymol and menthol.
Eucalyptus australiana var. "B" or E. phellandra is commonly known as one of the "narrow-leaved Peppermints". It occurs extensively on the mountain ranges of New South Wales and Victoria being especially abundant in the Braidwood and south coast districts of New South Wales. It is botanically identical to E. australiana but produces a different type of oil.
The yield of oil from the leaves and terminal branchlets averages from 3 to 4.5 per cent of a colourless to pale yellow oil. The oil consists of phellandrene (35 - 40 per cent) and cineole (20 - 50 per cent).
The oil has been extensively used for disinfectants, deodorants and many other industrial uses. It is an excellent solvent. Production has fallen dramatically as the selling price for this industrial oil has been too low to justify the hard work and high labour input required.
Eucalyptus globulus was discovered in Tasmania in 1792 by Labillardiere and is commonly known as the "blue gum". No eucalypt has received so much attention from botanists and chemists as this species. It has been cultivated in all parts of the world and the eucalyptus oil from E. globulus is the best known and most used of all eucalyptus oils. While it was distilled in Tasmania in 1880 it is no longer produced in Australia, having been replaced by higher yielding and better quality oils from other species.
The yield of oil from the leaves and branchlets averages from 0.75 to 1.25 per cent. The crude oil is a mobile liquid, normally light yellow in colour, with a pronounced odour of the volatile aldehydes which causes coughing and irritation to the mucous membranes. The cineole content is between 60 - 70 per cent and since in many instances the properties of the crude oil do not meet the specifications of most pharmacopoeias the oil has to be rectified to increase the cineole content and to improve its solubility in alcohol. After rectification the oil is water-white.
Because of the volume and availability of this type of oil on the world market it has become the standard eucalyptus oil for buyers everywhere.
Eucalyptus citriodora commonly known as the "lemon scented gum". A large tree often attaining a great height with a smooth whitish pale pink bark. Readily identified by the fragrant "citronella-like" odour of the crushed leaves. It grows extensively in Queensland in natural stands. However, it has been extensively cultivated as an ornamental tree and has been planted for commercial purposes in many countries.
The yield of oil from the leaves and terminal branchlets from forest trees varies from 0.5 to 0.75 per cent and from cultivated trees up to 2 per cent.
The principal constituent of the oil is citronellal and the oil is used for industrial and perfumery purposes. Large quantities of oil were once distilled in Queensland but Brazil, which has extensive plantations now produces almost all the oil from this species. The last report indicated that there were five million trees of E. citriodora in the state of Sao Paulo, Brazil, being used for oil production.
Considerable improvement has been made in recent years in the harvesting, materials handling and distillation of Eucalyptus polybractea. Continued progress would give Australia an opportunity to regain lost export markets for medicinal eucalyptus oil and would provide a chance to diversify farming activities in low rainfall country areas where the possibilities for other sources of income are limited.
Eucalyptus polybractea (Blue Mallee) is the major oil producing species which can be mechanically harvested and as the species is confined to Australia it gives us an excellent cost advantage over our competitors.
Machine harvesting is now a tried and tested reality with all of E. polybractea being harvested in this manner.
Our method of harvesting is to use a tractor, a specially modified tritter and a mobile still in tandem. The tritter (which is akin to a forage harvester) chops the mallee off just above ground level and throws it up a chute into the mobile still which holds about three tonnes.
The old method was to lop off the limbs of growing trees or use a hand axe or special sickle to cut mallee regrowth or coppice growth which springs from the stumps of the felled trees. Once the leaves had been cut they were loaded onto a vehicle, carted to the distillery, unloaded and packed into a distillation vat where the oil was removed. The spent leaves were then unloaded and dumped in a heap ready for burning. As well as being a significant part of the cost of production, it was very labour intensive and physically demanding work.
A later method was to put the leaves and twigs into a cylindrical brick or steel vat sunk in the ground. The vats held between two and five tonnes of leaves and stalk. The whole operation was relatively inefficient and labour intensive.
When the mobile still is filled it is uncoupled and a new still attached. When two stills are filled a second tractor tows the two stills in tandem to the distillery. Lids are placed on the stills and steam is connected at the base of the stills.
After the steam vaporises the oil the vapours are condensed in modern stainless steel condensers. Cooling water is supplied from a nearby dam. The mixture of oil and water is collected in a receiver where it separates on standing as the oil being lighter floats to the surface. The yield of oil varies but averages about one per cent of the material harvested.
The boiler is fired by timber and spent leaves from previous batches. Hopefully technology will soon be sufficiently advanced to make it feasible to have the steam generated by solar heat which is available in abundance.
When the steam has carried over the oil the mobile stills are towed out for emptying of the spent leaves and this is done very simply and efficiently. The whole operation has significantly reduced the labour effort and it has been achieved at a reasonable capital cost.
The original method was to place about 400 kg of leaves in ships’ water tanks to which water was added. The tanks would then be heated with wood or spent leaves from a previous distillation. When the water boiled the steam passed through the leaves separating the oil from the plant cells and carried it over in a vaporous state into a long pipe which acted as a condenser. The pipe was attached to the still at the top and passed under the water of a stream or creek. The oil and water condensed in the pipe and flowed into a suitable receptacle where the oil floated on the surface of the water and was collected.
Most of the eucalyptus oil presently produced in Australia comes from Eucalyptus polybractea. The major producing areas are the Inglewood and Wedderburn districts in Victoria and near West Wyalong in New South Wales.
The Victorian industry is almost entirely based on the use of public land which has been under lease from either the Department of Crown Lands and Survey or the Forest’s Commission since the early 1900’s. Some of this land has been harvested continuously for over 60 years. It is normal to harvest after two seasons growth or after one year where there is young growth on trees brought into production by rolling down and burning.
An interesting observation is that the land on which E. polybractea has been regularly cut has the purest and healthiest stands of E. polybractea. Provided that the regrowth is properly harvested at the right time there is no evidence of damage to the plant. In fact, it appears that the plant thrives under these conditions which are not unlike the regular burning off of the old wood which used to frequently occur long before white man discovered Australia.
Fertilisation of the species has been tried but the results have not been sufficiently encouraging economically to justify further work. In addition as the fertiliser was applied on the surface of the ground it tended to be utilised by weeds and other competitors rather than by the "Blue Mallee" which is deep rooted.
Although "Blue Mallee" is subject to some insect and fungal attack the damage has never been serious enough to consider the use of pesticides to control outbreaks. There is no evidence that native flora and fauna has suffered as a result of eucalyptus oil production.
Those of us in the industry who are mindful of its future are very conscious of the need for erosion prevention. Because the land has a relatively low rainfall and because cropping leaves the land relatively bare, it is important to exercise care and to take preventative measures when and where necessary. Most erosion problems start on sloping ground where there is a hard surface. After heavy rain there is a runoff from these areas which can produce a gullying hazard and carry silt in to water ways. A historical problem is that in the old days steel-wheeled wagons were pulled along gully tracks with the result that in wet weather the wheel marks became water channels.
However, by sensible measures such as relocated roadways, leaving vegetation close to creeks and streams, not cutting leaf from bare sloping ground, not harvesting too close to the ground thereby always leaving some natural cover and perhaps by contouring where necessary, erosion problems can and are being overcome.
It has been suggested by a vocal few that the industry should be abandoned and the land should be allowed to revert to its natural state, whatever that means. It is obvious those putting forward this point of view have a very simplistic attitude toward the subject and have very little understanding of the ramifications of their suggestions or of the repercussions that would flow from the introduction of them.
As already pointed out large stands of eucalyptus were rooted out after World War II to make room for wheat crops and that the available area of E. polybractea has been depleted as a consequence. However, this type of land clearance has long since ceased and there is no chance of further "Blue Mallee" land being lost.
It is true we do not have available sufficient "Blue Mallee" stands to dramatically increase production. Nevertheless, there is enough to possibly double production. After that it will be a case of establishing plantations. Until such time as plantations have been successfully established the public land will be essential for the survival of the industry.
Perhaps when private plantations have proven to be a viable proposition it may be possible to phase out public land, but in the meantime the industry needs the use of public land in order that it can foster and nurture the development of private plantations.
The advantages to be gained by the establishment of plantations are numerous. Land would be chosen which would allow mechanical harvesting. Seed would be selected to grow vigorous plants which would give a high yield and quality of oil. Plantations would increase leaf yield per ha and planting’s would be concentrated in a given area which would reduce the cost of transportation of the leaf to the distillery. Modern and efficient distilleries could be strategically located to cater for a planned throughput.
Returns would be relatively quick for a forestry product. Harvesting would commence after one year and a reasonable return could be expected after three or four years and after five years the area planted would be in full production.
Given all these advantages why hasn’t at least one commercial plantation been established? The reason is that we have not had the technology to grow the right varieties of eucalypt for eucalyptus oil production at an economic price. The capital cost to establish a plantation is great, the problems are innumerable and the risk of failure is very high in low rainfall areas.
The first pilot plantation was started in September 1911 at Emerald, Victoria, by Messrs J. Bosisto and Co. with the plant of E. macarthuri. This species grows quite well from seed and the result of the effort was quite satisfactory.
Since 1911 a number of trial plantations have been commenced in several areas. Over many years F. H. Faulding and Co. Ltd., Adelaide has experimented with the cultivation of eucalypts but for one reason or another it has never established a commercial plantation for oil production.
In 1972 the Australian subsidiary of the giant multinational corporation, Monsanto, looked into the feasibility of starting a plantation of Eucalyptus polybractea and concluded: "On the basis of the proposed size of the operation (2000 acres) and using proven yields the income is small compared with the money and effort expended. In addition the "pay-back" period (14 years) is long because of the need for staggered planting and a long wait before harvesting full acreage."
The Museum of Applied Arts and Sciences, Ultimo, Sydney, took a very active interest in all facets of eucalyptus oil production for more than 80 years and it was acknowledged as the leading and principal research institution in the industry, until it ceased these activities in 1980. Over the previous ten years or so, the research staff at the Museum had looked closely at the propagation and raising of E. polybractea and experimental plots have been planted since 1968. G. R. Davis and Co. near West Wyalong, NSW, has also been regularly planting small areas of E. polybractea over the last few years.
The outcome of this experimentation has shown that:
- There are up to 1,000,000 E. polybractea seeds per kg. Germination, under ideal conditions, varies between 50 and 80 per cent. Australian natives are often difficult to grow from seed and because of the lightness of the seed from this species no method has yet been found whereby the seed can be planted directly.
- To obtain the best quality clones which are known to yield a high quantity and quality of oil, experiments have been carried out with vegetative propagation. However, the results from these trials have not been satisfactory and further work will be necessary.
- It is possible to raise seedlings in a nursery from seed collected from known high yielding trees and this is the usual way of getting stock. Planting in jiffy pots has given the best results but they are expensive. Cheaper paper containers have been used with some success. However, it is hoped that open root planting will be possible as this would be the most economical method in the short term.
- It has been shown that the more plants per ha the higher the yield of oil. In practice it has been found that 9,000 trees to the ha give a good result. Yields have been in the order of 70 kg of oil per ha, but with further selection it may be possible to boost this to 100 kg per ha.
- Even using mechanical planting equipment the cost of raising and planting 9,000 seedlings to the ha is expensive. Weed competition can be a problem and a good seedbed preparation would appear to be warranted.
- As land suitable for E. polybractea usually has an annual rainfall of 400 - 450mm (16 - 18") planting out is a high risk period. It is usual to plant out after good rains to give the seedlings a start. However, follow-up rains are necessary and if no rain falls within six weeks, substantial losses are inevitable. Because of the low annual rainfall the planting out time is limited and therefore it is not feasible to plant a large acreage in any one year. Watering is not practicable and in any event the plants do not respond too well to watering.
The situation appears to have been reached where useful progress has been made and taking into account the present trial work being undertaken particularly in Western Australia, it should not be too long before commercial plantations are established.
Medicinal eucalyptus oils which are mostly used in pharmaceutical preparations must contain at least 70 per cent cineole. These oils do not contain phellandrene and must conform to the standards set out in the various pharmacopoeias. The trade supplies oil according to cineole content, i.e. 70 - 75 per cent, 80 to 85 per cent etc. To obtain these oils either an oil from a single species is used or oils from two or more species are blended. In any case it is usual to first refine the oil by rectification (re-distillation in vacuo). Rectification has these advantages. The cineole content of the oil will be increased where necessary. Residues and low boiling constituents of objectionable odour are removed. The oils are dehydrated which improves their keeping quality. The colour of the oil will be removed where necessary.
Eucalyptus oil from E. polybractea has these principal constituents: Eucalyptol (1,8 - cineole) (80 - 88 per cent), p-cymene, australol (p-isopropylphenol), cuminal, phellandral and cryptone. On the other hand eucalyptus oil from E. globulus has these principal constituents: Eucalyptol (1,8 - cineole) (60 - 72 per cent), pinene, volatile aldehydes, sequiterpenes and globulol.
Oils from other species of eucalypts have equally different constituents and therefore it is desirable to select for a particular use the type of oil with the best combination of constituents.
Medicinal eucalyptus oil produced from E. polybractea is widely used for the relief of cold and influenza symptoms. It is a unique natural product having antiseptic properties and the power to clear the nasal passages and bronchial tubes making it easier to breathe. A popular new use is to vaporise it in saunas. It is an excellent rub for muscular aches and pains and it has been widely used for many years by sportsmen to help keep muscles trim and supple. A use which is gaining widespread acceptance is the practice of adding eucalyptus oil to the laundry wash for cleaning and freshening clothes, which utilises its cleaning, deodorising and antiseptic properties.
Medicinal eucalyptus oils and eucalyptol are extensively used as a raw material and active ingredient of cough lozenges, inhalation sprays and drops, gargles, mouth washes, toothpastes, embrocation balms and ointments, liniments and soaps.
Eucalyptus oil is also used in antiseptics and germicidal disinfectants because of its pleasant odour and its effectiveness in killing bacteria. It is an excellent solvent which makes it an ideal spot and stain remover.
Industrial eucalyptus oils are used in the manufacture of household disinfectants and as an industrial solvent.
The spent leaves after the eucalyptus oil has been extracted is marketed as a mulch and ground cover. Sold under the trade-name Bosisto's Euca-Mulch, it is gaining rapid acceptance by landscape and home gardeners who like its natural appearance and bushland fragrance.
While the mulch is especially suitable for native gardens, it looks equally at home under shade, ornamental and fruit trees and in shrub and flower beds.
The mulch meets all the criteria of a first-class mulch and ground cover. It is weed and insect free and is non-toxic to animals and plants. It suppresses weed growth and reduces the need for watering. It allows excellent drainage, aeration and water penetration under all conditions. It stays in place even in very high winds and normal leaf-fall adds to its attractiveness. After 2 or 3 years it breaks down into an organic humus.
Tested by the Department of Agriculture and found to be satisfactory more work is being undertaken as it is believed the spent leaves could be an ideal addition to potting mixes.
The outlook for the future is bright. Prospects are excellent for increased exports and with the continued implementation of advances in science and technology Australia could again become the dominant supplier of eucalyptus oil to the world markets. I believe the industry is more important to Australia than its present size would indicate. It is demonstrably Australian, it is an integral part of our history, its past is colourful and romantic and it has the potential to be both a splendid tourist attraction and an important rural industry.