Rural Industries
Research & Development Corporation

MAY 1996

Registration As A Medicine Critical

Future Funding

Australia's Tea Tree Industry

Competition Set to Increase

Investment in R&D; to Date

Genetic Improvement of Tea Tree

Strategy Aims for 60% Improvement

Irrigating Tea Tree

North Queensland Yields Double NSW

Management Options

Weed Control Options Offer Huge Savings

Integrated Pest Control

When To Harvest?

Where Does the Oil Go?


Proving the Value of Tea Tree Oil

Antiseptic Value

Treatment of Tinea

Skin Sensitivity

Registration As A Medicine Critical

Registration of tea tree oil as an over-the-counter medicine both in Australia and overseas will be critical to the future of the tea tree industry.

That was one of the main findings of a review of the Tea Tree Oil Research and Development (R&D) program in 1994. The panel concluded that the lack of credible data on the effectiveness of tea tree oil as an antimicrobial agent is likely to be a major constraint on increasing the demand for the oil.

There is concern that the anticipated increased production of tea tree oil will drive supplies beyond demand, and thus reduce prices. Therefore ways of building demand must be the focus of future work by the industry.

The panel concluded that "Funding for R&D, particularly that on the antimicrobial efficacy of tea tree oil, must be increased if current obstacles to profitability are to be addressed promptly and effectively".

The panel assessed that investment in R&D on the production aspect of tea tree has been timely and effective in providing knowledge and technology to the industry. A critical factor in this being the establishment of close relationships between the industry, the Rural Industries Research and Development Corporation(RIRDC) and research providers.

Future Funding

The 1994 program review recommended that RIRDC should maintain its tea tree R&D program, but seek an increased level of industry funding.

The panel recommended that about $250,000 be spend on 'building demand' related R&D and $125,000 for 'supply-related' R&D, thus requiring a yearly budget of $375,000.

The Board of RIRDC agreed to continue supporting the program but required funding to be on a $1 for $1 basis from 1996/97 onwards. RIRDC requires that each of its 20-odd programs has a formal 5-year plan that is developed in consultation with the industry or stakeholders concerned.

Some of the returns to date on the investment made in R&D in the tea tree industry are outlined in this newsletter.

Key R&D Objective and Strategies

The panel that reviewed the Tea Tree R&D program in 1994 considered the likely future of the industry to be as outlined below:

The panel concluded that a future tea tree oil program should have the following major objectives:

  1. To improve and maintain the demand for tea tree oil.
  2. To increase the oil yield per dollar input.
  3. To maintain and further develop research infrastructure supporting the tea tree industry.

Australia's Tea Tree Industry

Tea-tree - Melaleuca alternifolia - occurs naturally in Australia only in a small area of northern New South Wales.

It has been used medically on a small scale ever since European settlement in Australia in Australia more than 200 years ago. Before that Aborigines also used it - in non-processed form - as a treatment for headaches, other pains and colds, and as an insect repellent.

Today, a growing number of plantations in Australia are now believed to produce between 180 and 200 tonnes of tea tree oil each year. With the average oil price of$50/kg, this takes the farm-gate value of the industry to around $10 million/year.

NSW is still the predominant producer, with increasing interest in North Queensland and in WA, and there is also small planting in the Ord River.

The oil is incorporated into many products, ranging from shampoos and conditioners to soap and cream. It is also used in liniments, foot balms, insect repellent and germicides.

Competition Set to Increase

While Australia currently produces about 99% of the worlds tea tree oil, there are indications strong prices are enticing other countries to consider establishing tea tree oil production.

China is apparently planning to plant large areas of the crop, and there is also interest coming from other Asian countries including India, Vietnam, Malaysia and Indonesia.

Zimbabwe is reported to have recently placed tea tree oil onto the market.

Investment in R&D to Date

The Tea Tree Oil R&D Program was established by RIRDC's predecessor, the Australian Special Rural Research Council, in February 1990.

At the time, the industry was only operating in Northern NSW, and was producing some 70 tonnes of oil, worth about $4 million. The farmgate price of tea tree oil was $55/kg.

Since 1990/91 $1.68 million has been directed into the tea tree R&D program by RIRDC and the industry. RIRDC is funded by the Commonwealth Government. The industry's contribution began at 13% and built up to 20% in 1994/95.

In addition, research organisations and the industry have contributed significantly to the cost of the program. For example, NSW Agriculture has directed around $2 million into the tea tree R&D program to date.

Tea Tree Research Program 1989-1996
Production R&D Organisation Funding

  • Irrigation as a management tool for tea tree oil
DAN-19A 41,100 1990
  • Viable plantation production of oil of Melaleuca
UMA-4A 15,000 1991
  • Breeding strategy for tea tree oil
CSF-43A 1992
  • Genetic variation of oil production and quality in tea tree
ANU-11A 20,846 1993
  • Breeding and selection of Australian tea tree
DAN-87A 210,822 current
  • The insect fauna of Melaleuca alternifolia
DAN-61A 5,000 1992
  • Herbicides for weed control in tea tree
DAN-74A 71,953 1994
  • Insect management in tea tree
DAN-91A 81,087 current
  • Towards non-chemical control of weeds in tea tree plantations
US-20A 110,480 ??
  • Prediction of the growth and oil content of tea tree
DAN-60A 10,065 1992
  • Factors affecting oil yield in tea tree
DAN-58A 92,124 1993
  • Oil gland research techniques
DAN-59A 5,000 1994
  • Low and high field spectroscopy for tea tree oil analysis
HAC-5A 5,500 1991
  • The development of the North QLD tea tree industry
DAQ-184A 28,620 current
Safety & Efficacy R&D
  • Clinical testing of tea tree oil as an antiseptic
PHA-1A 29,350 1991
  • Tea tree oil in the treatment of tinea pedis
PHA-2A 93,150 1992
  • Assessment of skin sensitivity and irritant potential of tea tree oil
PHA-3A 20,750
  • Tea tree oil: toxicology and clinical use and clearance
SA-1A 7,500 1992
  • Development of appropriate assays procedures to measure antimicrobial activity
UMA-12A 57,240 1994
  • Antimicrobial properties of tea tree
UMA-11A 1995
  • The antimicrobial activity of tea tree oil
UWA-24A 144,492 current
  • Significance of cineol for the bioactivity and irritancy of tea tree oil
DAN-104A 99,656 current
  • FDA testing
Mitech 1 73,000


Genetic Improvement of Tea Tree

Expansion of the tea tree oil industry requires the use of plantations of high genetic quality.

In the first stage in the development of a breeding program, researchers Drs Penny Butcher and Mike Slee set out to establish the degree of genetic variation within the species used for oil production (ANU-11A).

Five different oil types were identified in Melaleuca alternifolia trees, including the one useful 'type' variety that has cineole levels ranging from 0.8% to 8% and terpinen 4-ol levels from 38-42%.

Differences in leaf oil composition between natural populations provide opportunities for selection for oil quality.

Results from progeny tests of high heritability for oil yield together with the wide range of variation in growth rate and biomass production, in oil yield and coppicing ability indicate considerable gains can be expected from selection for single traits.

Negative correlations between oil and yield and plant biomass suggest it is not possible to simultaneously achieve major gains in the two traits.

Maintaining biomass production at current levels, gains of 17% in oil yield and 14% in coppicing ability can be expected in one generation, following selection of the best one in ten trees.

For more information contact Ms Penny Butcher at the CSIRO Division of Forestry on (06) 281 8206.

Strategy Aims for 60% Improvement

As a result of a tea tree breeding strategy that was instigated in May 1993, the first improved tea tree seeds should be available by the end of the 1996.

The $430,000 program, funded by RIRDC and Australian Tea Tree Industry Association(ATTIA), NSW Agriculture and CSIRO, is being run by Gary Baker and John Murtagh of NSW Agriculture, and John Doran of CSIRO Division of Forestry and Forest Products.

The aim is to provide seed of progressively improving genetic quality up to the year 2000.

Dr John Doran says the profitability of tea tree plantations is very sensitive to yield and price. "At current prices and yields (120-200 kg per ha) growers are doing well, but they would need a substantial increase in productivity to remain ahead in the price dropped significantly", he said.

There is big scope to improve yield per ha and oil quality. "We hope to improve yields by 30% in the first instance and by progressively thinning out the poorer lines within provenances to increase yield by 60%", he said.

The basic elements of the breeding strategy have been established in various parts of the NSW North Coast including:

Irrigating Tea Tree

Naturally growing tea tree is found in swampy areas of the NSW North Coast.

This prompted scientists to investigate the benefits of irrigating tea tree so as to reproduce a wetter environment than exists on plantations (RIRDC Project No. DAN-19A).

The trials at Warallah, near Lismore, were run over three years, of which all had dry spells. Irrigation produced a response of increased herbage and oil production in only one of these years.

The plant appears to be adapted to producing flush growth even under dry conditions (mid-September to mid-November). Even though water stress will reduce production after that, in many districts rainfall increases during summer to acceptable levels.

Dr John Murtagh points out that the trial was located in an area where the sub-soil was kept moist by groundwater. He says it is important to choose sites like this to avoid the need for irrigations.

He emphasises that it is vital to irrigate tea tree at establishment. "That is for the first month or two, while the seedlings are being established", he said. Many growers in NSW set up temporary irigation systems for this period.

For more information contact Dr John Murtagh at Wollongbar Agricultural Institute on (066) 261 200.

North Queensland Yields Double NSW

Tea tree oil yields 1.5-2 times higher than the average in northern NSW are being experienced on tea tree plantations in North Queensland.

This has been reported by James Drinnan, Horticulturalist with the Queenland DPI, in the Mareeba-Dimbulah Irrigation area.

James is working on a R&D project (DAQ-184A) which is facilitating the development of the tea tree industry in this area, where many tobacco growers are seeking alternative crops.

There are currently 40 growers with about 220 hectares of tea tree, and harvesting has only occured for the last 2 1/2 years. The crop is being growing under existing irrigation systems set up for the tobacco, so the production costs are higher, although James says this is more than made up by the increased growth rates and oil yields of the tea tree.

"The aim is to develop irrigation scheduling for maximum oil yield and quality and to establish a gene pool of selected superior plants for the area," he said. Irrigation of tea tree in this area is vital because of the lack of sub-soil moisture, except for the wet season.

For further information contact: James Drinnan on (070) 928 555 or fax (066) 923 593.

Management Options

In early research on management options for plantation raised tea tree (UMA-4A), Dr Lyall Williams found that while tea tree occurs naturally in swamps and water courses, it does not flourish in these conditions. Optimum production of oil the trees require good soil with adequate irrigation and drainage.

Oil content was found to vary seasonally, with higher levels in the summer months of November to May and gradual reduction during the winter months to the end of October.

Weed control was found to be desirable, either by chemicals, harrowing or grazing. The recommended plant spacing of around 25,000/ha allows access for weeding activities, insect control, fertilising etc.

For more information contact Dr Lyall Williams at Macquarie University School of Chemistry on (02) 805 8303.

Weed Control Options Offer Huge Savings

A minimum of $1,100 per hectare can be returned to tea tree growers in weedy situations by adopting the results of a recently completed research project on improving weed control options (DAN-74A).

Project Leader Tony Cook of NSW Agriculture says apart from these financial gains, new recommendations will allow for increased managerial choices, superior weed control and less likelihood of developing herbicide resistance.

Approximately 80% of tea tree growers surveyed as part of the project stated that weeds were a major limitation to production and half were dissatisfied with their current weed control techniques.

The five most abundant weeds were kidney weed (Dichondra repens), carpet grass (Axonopus affinis), sedges (Cyperus spp.), fleabane (Conyza spp) and couch grass (Cynodon dactylon). It was shown that a 97% reduction in yield was a consequence of high weed densities in the first few months after planting.

Sixty five herbicides were screened for a range of tea tree growth stages, in order to identify treatments that were safe to tea tree, provided adequate weed control and were not too cost prohibitive.

In some cases, recommended treatments arising from the project are 80% cheaper that previously recommended treatments and exhibit little difference in weed control and safety. There was no detectable level of herbicide residue in oil samples from tea trees treated with some of the new recommended treatments.

"Although considerable cost savings were made with new treatments (blanket applied), there are further savings and benefits if the practice of directed spraying was properly developed," says Tony Cooke. "This could allow the use of herbicides normally damaging to tea trees."

A weeds identification and weed control booklet will transfer information gained from this project to relevant people and will be published in 1996.

For more information contact Tony Cook at the Tamworth Centre for Crop Improvement on phone (067) 631 100 or fax (067) 631 222.

Integrated Pest Control

Concern over the use of chemicals for pests in tea tree plantations, and the potential for residual pesticide contamination of the oil, has led to a recent study of sustainable pest management strategies for tea tree plantations.

Defoliating insect pests, particularly the Pyrgo beetle, sap sucking mites and psyllids, greatly affect the oil yield of plantations. These pests cause the loss of leat tissue and reduce plant growth. Losses of millions of dollars to producers can occur.

Project Leader Gus Campbell of NSW Agriculture is looking for ways of minimising the use of synthetic pesticides in the tea tree industry. Gus has been monitoring the effects of climatic conditions on insect pests. He has found that the number of insects affecting tea tree is increasing. "Damage by some of the weavils, such as the Elephant weavil, is growing, and this pre-disposes the tea trees to fungal infections," he said.

The industry is facing a difficult situation. Its commitment to the policy of zero residues in tea tree oil, means that chemical companies are unwilling to register chemicals for use on tea tree.

"Currently methonyl is the only chemical registered for use, and it needs to be used at quite high rates to be effective. While some of the synthetic pyrethroids may be effective against these insect pests, and may not lead to residues, chemical companies are concerned about the nil residue level and are not registering these chemicals for use on tea tree. Although some growers are getting permits to use them for use in special one-off situations," he said.

Gus has been conducting trials on a monitoring technique to detect early flight activity by Pyrgo beetles. If successful, this could allow better control in early spring and when combined with strategic spraying delay the pests building up in crops in summer or early autumn.

For more information contact Gus Campbell on (066) 28 0604 or fax (066) 285 209.

When To Harvest?

Determing the best time to harvest tea tree and ways of increasing oil yield was the focus of a research program based at the Wollongbar Agricultural Institute (DAN-58A).

Researcher Dr John Murtagh says oil concentration in tea tree varies widely. In the same plantation it changes from month tomonth, and sometimes from day to day. Oil concentration also varies between plantations.

"These variable trends make it difficult to identify what controls the oil concentration and to decide when the oil concentration is at the best level to harvest", he said.

The average oil concentrations were found to be highest in summer/autumn when most of the leaves on a tree had developed during the warmer months. The tea trees were water stressed even when they were irrigated. Irrigation only gave a 10% increase in oil yield.

Whilst water stress persisted throughout most of the dry season (September-December), the oil concentration generally increased over this period and more than doubled in one experiment. No one cultural practice or local environment appeared to be able to reduce the water stress which is endemic in tea trees grown in plantations.

The researchers concluded that from a production perspective, harvesting should be delayed until the crop canopy is fully developed.

For more information contact Dr John Murtagh at the Wollongbar Agricultural Institute on 066 261 200.

Where Does the Oil Go?

In 1992/93 Dr John Murtagh of NSW Agriculture visited Washington State University to investigate how peak periods of oil yield in tea tree can be predicted.

He worked with the world renowned essential-oils research groups at the University assessing the different ways oil concentration varies, using methods developed for peppermint.

Dr Murtagh was looking for an explanation for what happened to tea tree oil when oil levels dropped. He found some was lost into the air through volatisation from the oil glands in leaves, but was unable to prove definitively that the balance was used as plant food with current research techniques.

For more information contact Dr John Murtagh, Agricultural Water Management, Lismore, on (066) 25 1510.


In early 1992, Sue Ackroyd reviewed the paths the industry must take to achieve clearance of its products for medicinal use was completed by Sue Ackroyd. She described the registration system for tea tree oil products in Australia and the American monograph systems.

She said the industry lacked the hard data needed to easily gain entry into the monographs, which is required to generate a solid basis for entry into the US and other world markets.

In 1994 Thomas Riley, of t he Department of Microbioloty at the University of Western Australia, reviewed the current information on the efficacy and safety of tea tree oil.

He concluded that the work done on antimicrobial activity of the oil so far had been done in a fragmented way. He said there lacked valid susceptibility testing methods, and there was only one or two published clinical trials and little susceptibility data.

Dr Riley was concerned about the lack of tea tree oil data published in respected and scrutinised journals.

He recommended that susceptibility tests for bacteria, fungi, and possibly viruses, be developed and validated; for a wide number of organisms to be tested against tea tree; and for other tests to be carried out relating to the action of tea tree oil, oil quality, animal experiments and human clinical trials.

The Cineole Question

The present trend in the tea tree oil industry is to produce and market oils that contain as little cineole as possible.

However, researcher Dr Ian Southwell of NSW Agriculture says there is no scientific evidence published to justify this.

Some authors suggest cineole is a skin irritant while others report clinical trials that did not detect any irritation. Indeed, the results of Dr Southwell's research shows that cineole is not harmful to the skin and is not detrimental to the anti-bacterial action of tea tree oil.

The industry has set a limit on 1,8-cineole of 15% and many would like to see levels as low as 5%. Ian Southwell says there is a perception that oils with ultra low levels of cineole are superior to oils with higher levels of cineole. He says cineole, in concentrations above 15% is not detrimental to the antimicrobial activity of the oil and does not cause skin irritation.

The trials are being conducted in such a way that they will be recognised by the US Food and Drug Administration. The aim is to assist the acceptance of tea tree oil as a pharmaceutical, particularly by the US.

What do you think about cineole? We need your advice on the relative importance of oil concentration versus cineole concentration!

There is hope that further markets may be developed in Europe. Prospects and attitudes to botanical medicines such as tea tree oil in the UK and Europe were investigated by Dr Southwell in 1995.

He identified potential strategies for gaining entry for tea tree oil to the British and European pharmacopoeias and hence lessening the industry's current reliance on gaining entry to the US registration system. As a result, the German Pharmaceutical Codex (DAC) has elaborated a draft monograph for tea tree oil.

For more information contact Dr Ian Southwell, Wollongbar Agricultural Institute, on (066) 261 200.

Proving the Value of Tea Tree Oil

Tomas Riley has followed up his recommendations, with actions, having proof of tea tree oils antimicrobial action published in several internationally recognised medical journals.

His preliminary research results show that the oil kills many bacteria present in common infections, including some staphylococci and streptococci.

The research is being conducted by researchers at the University of Western Australia and the new Western Australian Centre for for Pathology and Medical Research (RIRDC Project No. UWA-24A).

In related research, being funded by a commercial company, Associate Professor Riley is currently testing the effectiveness of tea tree oil for treating thrush in a trial in Perth

The aim is to provide the necessary information to help make tea tree recognised by the world's pharmaceutical and medical communities as a therapeutic agent.

If the research succeeds it will greatly benefit the Australian tea tree industry by increasing demand for the oil, particularly from the United States market.

For more information contact Tomas Riley, Department of Microbiology, University of WA, on (09) 346 3690

Antiseptic Value

In early research at Macquarie University (UMA-12A) the antimicrobial activity of a large number of commercial tea tree oils was examined.

Results demonstrated the importance of terpinen-4-ol for activity against microbes including those causing acne, tinea, dandruff.

The powerful antimicrobial activity of p-cymene, a minor component of tea tree oil, was confirmed. Some micro-organisms are highly susceptible to a combination of terpinen-4-ol and p-cymene.

Contact Dr L Williams, Macquarie University, (02) 850 8612).

Treatment of Tinea

Tests of the treatment of tinea with tea tree oil showed that the symptoms of the problem were much reduced when tea tree oil was applied.

In the trial, Professor Barnetson of Sydney's Royal Prince Alfred Hospital Department of Dermatology, treated 104 patients (PHA-2A).

The tea tree oil treatment however, did not cure the actual fungal infection as effectively as the commonly used manufactured product based on tolfonate.

Contact: Professor R. StC. Barnetson on (02) 516 6862.

Skin Sensitivity

Although tea tree oil has been used for more than 60 years in non-prescription pharmaceutical products, no skin sensitivity or irritation potential tests appear to have been published.

In a project conducted by Pharmaco (PHA-3), creams containing a range of concentrations of tea tree oil were formulated in a non-irritating base and stability tested and applied daily to volunteers over a period of 28 days.

Tea tree oil was not found to produce any significant skin sensitivity or irritation even at the higher concentrations.

Further tests on skin irritancy to tea tree oil is being conducted by Dr Ian Southwell of NSW Agriculture (DAN-104A).

Contact Dr S Freeman, Pharmarco, on (02) 413 4760.

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Last updated: 30 August 1996
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