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Rural Industries
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|| Introduction || Project listing|| Project Summaries ||
Tea tree (Melaleuca alternifolia) is native to the north coast of New South Wales. Its oil has gained widespread therapeutic use for fungal and microbial infections but is not yet registered for use by the medical profession.
The current annual production of tea tree oil in Australia is about 200 tonnes, having a farmgate value of around $10 million. Because of recent plantings in northern NSW and in North Queensland, it is likely that supply will exceed market demand, at least in the short-term, and hence depress prices.
Current hopes for continued and increased market demand are largely based on acceptance of tea tree oil by the US Food and Drug Authority for first aid and health care.
The outcomes of recent industry/RIRDC sponsored submissions are still not clear but a face-to-face consultation with the US FDA in 1995 indicated certain deficiencies in submissions to date.
These deficiencies are currently being addressed.
Research Highlights for 1996-97:
INSECT PEST MANAGEMENT IN TEA TREE
Objectives
To develop an effective sustainable pest management strategy for
the Pyrgo beetle and other pests of tea tree by:
· correlating the incidence of Pyrgo in the field with weather parameters,
and refining the maximum temperature threshold values for larval and egg
survival to account for field observations and to improve predictive modelling;
· evaluating a monitoring procedure for detecting Pyrgo in the field;
and
· screening selected insecticides and other chemicals for efficacy
against Pyrgo in the laboratory and the field.
Background
The tea tree industry of northern NSW and southern Queensland has developed over the last 20 years from a fledgling cottage industry into a substantial producer of some 260 tonnes of tea tree oil per annum. The early industry was based on bush harvesting but has now progressed to one of plantation culture using improved cultivars on more than 4,000 ha. Although the industry faces a number of problems, one of the more important affecting production is caused by a number of insect pests - the major one being Pyrgo beetle.
Insect problems are recognised and acknowledged by most growers, but little is known about the ecology of Pyrgo, and this has limited the development and implementation of appropriate control strategies. The industry has been promoted as being "clean and green", implying minimal or no use of insecticides, but this is belied by the substantial evidence (residues in the oil) showing that unregistered insecticides have been used on many crops. This is partly caused by the paucity of insecticides (only one is registered for use in NSW) legally available to growers, and there is clearly the need for a range of products to be available for use.
If rational insect control strategies are to be developed and implemented for the industry, then it is important to have a better understanding of the ecology of the pests concerned. Once this is established, potential insecticide and other control measures can then be devised and evaluated.
Research
Considerable field and laboratory research has been undertaken over the last three years to investigate the various factors which, collectively, result in loss of foliage and oil production. These have included studies on the ecology of the insects concerned, on the development of systems for monitoring the first occurrence and incidence of insects in plantations, on screening cultivars for insect resistance, and on evaluating a range of insecticides and other chemicals for potential use in chemical control strategies. This latter activity was instigated part of the way through the project, when insecticide residues were detected in oil - from crops clearly treated (illegally) with insecticides not registered for the purpose.
Outcomes
There is now an excellent understanding of the ecology of Pyrgo and some of the other insects which also cause yield losses. A practical monitoring system based on sticky yellow traps has been developed and this will allow the more rational application of control strategies including the reduction in use of insecticide treatments. Several alternative insecticides have been evaluated, and been shown to provide more effective control than the current sole product (methomyl).
Implications
Growers now have a better understanding of the population dynamics of Pyrgo, and of the importance of other insect pests such as mites and psyllids. With the development of improved monitoring using sticky yellow traps, there is now the opportunity to detect the presence of Pyrgo earlier than on-plant inspections, to allow the identification of localised areas of beetle activity, and to reduce insecticide costs by rationalising their use. There may be an added opportunity for the industry to employ scouts to undertake this monitoring and to advise growers on the need to use insecticide treatments.
Illegal use of non-registered insecticides is a potential "time bomb" that, if not addressed quickly, will seriously harm the industry. Several potential insecticide products have been evaluated and found to be more effective than the current permitted product, methomyl. Steps should be taken urgently to secure their registration for use on tea tree.
This project has highlighted the need for further research on control of mites and psyllids, and on the screening of insecticides to determine their potential for leaving residues in oil.
RIRDC Project No: DAN-91A
RESEARCHER: Mr Gus Campbell
ORGANISATION: NSW Agriculture PO Box 72 ALSTONVILLE NSW 2477 PHONE: 066
28 0604 FAX: 066 28 5209
TOWARDS NON-CHEMICAL CONTROL OF WEEDS IN TEA TREE
Objectives
· To survey tea tree growers to establish the range of weed
problems encountered, and the scope of current weed control techniques
used in tea tree cultivation.
· To identify the mechanisms by which weeds inhibit the growth and
oil production of established tea tree plantations.
· To define practical methods of weed control for plantation managers,
which minimise the use of herbicides.
Background
The perception of the tea tree industry is that weeds inhibit plantation production in two phases - establishment and regrowth.
The extent to which weeds affect the regrowth of tea tree by competing for light, nutrients and water has not been quantified, but the industry perception is that it is a real but variable problem. It is postulated that weed problems are linked to loss of fine roots of tea tree following coppicing. In these situations, the tea tree plant has weakened competitive ability against rapidly growing annual weeds until regrowth has been well established. The use of herbicides, as is currently practiced, is seen as damaging to the image of the product (tea tree oil), by growers and potential consumers. A range of cultural practices additionally used by growers, could form the basis of a non-chemical system of weed control in plantations.
This study seeks to evaluate these alternatives. The information gained should provide guidance on when weed control is required during the regrowth cycle, and what the method used must achieve if it is to be successfully adopted.
Research
A wide range of pot and field experiments were conducted to provide more information on the nature of root and top growth in coppiced tea trees, to allow a better understanding of the physiology of the crop in competition with weeds at different stages of its regrowth. The response to nitrogen nutrition was also examined.
Concurrently, other studies were undertaken to determine the effectiveness of various weed control strategies such as herbicide use (overall and strip treatments), cover crops, mowing, mechanical cultivation, and hand hoeing. These trials were undertaken at several localities over a three year period.
Outcomes
The results of these studies showed that weeds reduced tea tree leaf yields by an average 27% (range 9 to 47), but without affecting oil concentration or quality. This loss in yield is associated with competition for light, water and nutrients (especially nitrogen).
Two features of the regrowth cycle of tea tree are thought to be relevant to the crop's competitiveness after harvest: the first, "coppice vigour" (the high relative growth rate of new shoots from the cut stump) increases the crop's ability to compete for light; while the second, death of fine roots about halfway through the regrowth cycle, reduces the crop's ability to compete for water and nutrients in the latter half of the regrowth cycle.
When all weed control strategies were compared, herbicides continued to provide the most effective control, while mechanical cultivation was the best of the non-chemical methods. Other strategies used by the industry may also be effective, but they need to be assessed against these two standards.
Implications
While the use of herbicides still provides the most effective method of weed control, non-chemical methods can also be used but, irrespective of the method selected, it is imperative that it be implemented in the latter half of the regrowth cycle when competition from weeds is greatest.
RIRDC Project No: US-20A
RESEARCHERS: Dr BG Sutton & Dr RD Cousins Dr J Murtagh ORGANISATION: School of Crop Sciences Agricultural Waste Mgt Sydney University NSW 2006 GOONELLABAH NSW 2480
PHONE: 02 9692 2050 066 251 510 FAX: 02 9692 4172 066 245 207
BREEDING AND SELECTION OF AUSTRALIAN TEA TREE FOR IMPROVED OIL YIELD AND QUALITY
Objective
· To select and breed seed for economic gains in oil characteristics. Gains in yield and quality are considered essential if the Australian tea tree industry is to prosper against overseas competition and the downward pressure on oil prices.
Background
The Australian tea tree industry has developed from bush production to plantation production. Seed for planting is collected from natural populations using only rudimentary selection to ensure that oil quality meets industry standards. The yields of oil from plantations are variable; there is much scope to improve both the amount and quality of the yield.
Research
During the first three years of the project (1993-1996), seven field trials were established to determine the genetic variability in oil yield and quality. Two of these trials were then developed as seed orchards to provide improved seed to the industry. A natural stand of 783 trees was sampled, trees were analysed and ranked for oil concentration, terpinen-4-ol and cineole. Selecting the best 74 trees for seed production provides a selection pressure of >1:10. This ratio will enable genetic gain for selected traits.
A progeny trial of 204 families will be further tested for oil characteristics, superior trees selected and inferior trees culled to prevent them breeding with superior trees. The superior trees will grow on and flower to produce genetically improved seed. The coppicing ability of families grown at different sites will also be used to select superior families in the orchard.
Outcomes
Variation of key commercial traits were significant at the provenance, family and individual tree levels. Heritability (narrow sense) was high (0.51) for oil concentration, moderate (0.37) for cineole% and low for the growth parameters of plant height (0.21) and stem diameter (0.14). No adverse genetic correlations were found between oil concentration and plant height and diameter.
The performance of families across two sites (family x site interaction) was reasonably consistent, indicating that it will be possible to select families with good general adaptability in a single breeding population, thus avoiding the extra cost of establishing multiple breeding populations in different environments.
The best performing provenances were identified and seed from these areas will be released to the industry. The controlled pollinations in 1995 have produced seeds, indicating that the methodology used has potential.
Implications
All the indicators from the first phase of breeding point to very substantial economic gains being achieved by the breeding project. Three years is a very short time in tree breeding and more time is needed to produce the much improved seed required to ensure the successful development and survival of this industry.
RIRDC Project No. DAN-87A
RESEARCHERS: John Murtagh Gary Baker John Doran ORGANISATION: Agric.
Water Man. NSW Agriculture CSIRO 2 Sunnybank Av. Wollongbar Agric. Inst.
PO Box E4008 Goonellabah NSW 2480 Wollongbar NSW 2477 Kingston ACT 2604
PHONE: 066 251510, 066 261104, 02 6281 8319
FAX: 066 245207, 066 283264, 02 6281 8266
EMAIL: bakerg@agric.nsw.gov.au John.Doran@ffp.csiro.au
PUBLICATIONS:
Doran, J. C. (1995). Estimating seed quantities for tea tree plantations. Australian Tea Tree Industry Association Newsletter, April 1995. Doran, J. C., Baker, G. R., Murtagh, G. J. Williams, E. R. and Morris, S. G. (1996).
"Breeding and selection of Australian Tea Tree for improved oil yield and quality 1993 to 1996" Review Report for the Rural Industries Research And Development Corporation and the Australia Tea Tree Industry Association. Doran, J. C., Baker, G. R., Murtagh, G. J. and Southwell, I. A. (1996).
"Breeding and selection of Australian Tea Tree for improved oil yield and quality" Final Report for Rural Industries Research And Development Corporation.
SIGNIFICANCE OF CINEOLE FOR THE BIOACTIVITY AND IRRITANCY OF TEA TREE OIL
Objective
· To increase the market demand for tea tree oil by measuring and documenting data on the skin irritancy and minimum inhibitory concentrations (MICs) of different grades of tea tree oil that might be required by regulatory bodies like the USFDA for monograph acceptance.
Background
Approximately 200 tonnes of tea tree oil, valued (farm gate) at $10m, are currently produced in Australia per annum. The product is used as an antimicrobial antiseptic oil or formulated into value added creams, shampoos, soaps, mouthwashes, toothpastes etc. A significant rural industry is being established around the propagation, production, processing, formulation and marketing of tea tree, the oil and its products. Plantations are expected to yield 400 tonnes pa by the late 1990s.
However, one factor hindering the broadening of the tea tree oil market base is that oil reach in cineole is considered to be of high skin irritancy and therefore not of a marketable standard.
Research
Standard clinical procedures were used to test cineole and tea tree oil for skin irritancy. Twenty five human subedits were subjected to occlusive patch testing applied to the upper arm or back for five days per week for three consecutive weeks. The patch was removed at 24 hour intervals and any skin reaction noted. Subjects reacting allergically to the test substances were withdrawn from the irritancy trial and were used in further testing for allergic reaction to individual components or fractions.
More than 20 strains of bacteria were used to test numerous tea tree oils with varying levels of cineole concentration for antimicrobial activity.
Outcomes and Implications
The results of this research have major implications for the industry. Some years ago, oils with 5-10% cineole were perfectly acceptable in the marketplace. In recent years though, buyers have been seeking oils with less than 5% and sometimes less than 3%.
This research shows clearly that there are no grounds for promoting low cineole oils other than for avoiding low terpinen-4-ol oils. If all buyers could be convinced of this, more tea tree oil could be offered for sale, providing a yield boost to many producers.
The results of the project should aid the marketing of tea tree oil. It documents: 1) the absence of skin irritancy for formulated preparations; 2) the non-allergenic nature of most tea tree oil constituents; 3) methods for the removal of some possible allergens; 4) a wider range of tea tree oil-susceptible microorganisns; 5) specific MIC values for a range of oils; and 6) enhanced MIC values for specific oils.
RIRDC PROJECT No: DAN-104A
RESEARCHER: Dr Ian Southwell
ORGANISATION: NSW Agriculture Wollongbar Institute WOLLONGBAR NSW 2477
PHONE: 066 26 1224 FAX: 066 28 3264
DEVELOPING THE NORTH QUEENSLAND TEA TREE INDUSTRY
Objectives
· To facilitate the rapid development of the knowledge base on the
production of tea tree oil in the Mareeba Dimbulah Irrigation Area, Qld.
· To develop guidelines for irrigation scheduling for maximising
oil yield and quality.
· To establish a gene pool of selected superior plants.
Background
Tea tree oil production is a relatively new industry on the Atherton Tablelands in North Queensland. Interest in tea tree oil production was generated as an alternative crop for tobacco. The production systems being used now are based on New South Wales information, use high densities, and are irrigated. Due to differences in climate and soil types it is essential to adapt the findings from New South Wales research work for North Queensland conditions. Environmental and management effects, particularly irrigation, look to have a major impact on oil yields.
Research
Information on tea tree production has been gathered from key researchers working with tea tree. A soil moisture monitoring system (Environscan) has been used to investigate water use and water requirements of tea trees in North Queensland. Data has been collected on oil quality and quantity and the factors affecting it. Several seedlings have been identified as having superior oil concentration and quality. Superior planting material has also been sourced from the tea tree breeding program and is being evaluated at two locations in the Mareeba Dimbulah Irrigation Area.
Outcomes
Information was presented to growers via field days, newsletters, progress reports, presentations at growers' meetings and farm visits.
Irrigation scheduling guidelines have been developed. Mature trees use 0.8-1.0 times the pan evaporation rate which is equivalent to a total water requirement of I OML/ha/year or 7.5ML/ha/year when rainfall is subtracted.
Major factors influencing oil concentration and hence yields identified include genotype, time of year, nutrition, irrigation, and seedling vs coppice growth.
Implications
This project has helped with the very successful development of the North Queensland tea tree oil industry. There has been a rapid expansion of the industry and yields and oil quality have been excellent.
RIRDC Project No: DAQ-184A
RESEARCHER: James Drinnan
ORGANISATION: Queensland Department of Primary Industries, PO Box 1054
MAREEBA QLD 4880
PHONE: 070 928555 FAX: 070 923593
Last updated: 22 October1997
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