There are biosecurity measures in place at national and state level to reduce the risk of exotic pests and diseases entering Australia and Western Australia. Plant Health Australia are currently working on a biosecurity plan for the truffle industry. It focuses on exotic pests and will provide information on threat identification and pest risk assessments, risk mitigation and preparedness.
However, it is important to have to good hygiene practices in place on your farm as there are some pests and diseases of truffle orchards already present in the state and you need to be alert and prepared for possible future incursions of exotic pests, diseases and competing fungi.
Poor on-farm hygiene can lead to:
- reduction of product quality through pest and/or disease damage;
- reduction of yield through product loss from damage and/or competition from other mycorrhizal fungi; and
- contamination of product with inferior products
It is impractical to stop all pest and disease movement into your property but you can minimise the risk.
Pests, diseases and competing fungi
Pest and diseases
Pests and diseases already found in Western Australia include black beetle, various weevils, snails and slugs. More information on those and other pests can be found on the Pest and diseases of truffles and their host trees webpage.
There a number of truffle pests not known to occur in Australia that have the potential to damage the truffle industry if they do enter the country. Truffle beetle (Leiodes cinnamomea) is present in Europe where it often causes devastating losses. Other Leiodes species do occur in Australia, their activity in truffle orchards is not yet known. Truffle flies (Suillia spp.), lay eggs in the maturing truffle resulting in damage and loss of value.
Exotic diseases of truffle host trees include sudden oak death (Phytophthora ramorum), oak dieback and phytoplasma-associated diseases. These diseases can kill truffle host trees.
Ectomycorrhizal fungi other than Tuber melanosporum can outcompete or replace the T. melanosporum on host roots. This can result in reduced or contaminated yield.
If other Tuber species colonise the tree roots they may outcompete the desired truffle species. Other Tuber species of primary concern are:
- Tuber brumale (winter truffle) – already present in some eastern states of Australia but not yet formally recorded in Western Australia.
- Tuber indicum (Chinese truffle) –presumed to be very competitive and has a broad host range. Truffles of this species have been imported into Australia as food items.
There are a range of endemic fungi in Western Australian soils that may be potential competitors to T. melanosporum, including Scleroderma spp. Some consider the replacement of ectomycorrhizae formed by the targeted truffles by native ectomycorrhizal fungi is one of the most important causes of truffle cultivation failures (Miguel 2013).
If not already present in the soil prior to planting competing and contaminant fungi can find their way into an orchard in a number of ways:
- Introduced in soil on machinery, equipment, shoes and/or animals that have been on other properties.
- On the plant stock used if the incorrect species has been used as inoculum or if plants have been contaminated by endemic fungi in the nursery.
How to implement good on-farm hygiene
The key to good on-farm hygiene is to reduce the introduction of foreign soil and plant material into your orchard to the lowest practicable level. The key areas you will need to look at are people, machinery and equipment, production practices and animal management.
Disinfectants are used in good on-farm hygiene practices to disinfect footwear, machinery, vehicles and equipment to prevent the spread of unwanted fungi and soil-borne diseases. For truffle orchards chlorine based bleach is a good option.
People entering the property, including staff, contractors, utility providers and tourists may bring contaminants from overseas, interstate and/or other properties. It is vital that people are informed of the need for biosecurity measures and that they comply with your procedures. Below are some procedures you could implement on your property.
- Limit the number of entry points to the property and ensure adequate signage to inform visitors of the hygiene requirements for entering the property. Have a visitor checklist to ensure all relevant people are made aware of designated parking areas, wash down stations and wash down protocol, permitted areas and off-limits areas.
- All staff should be briefed on the importance of biosecurity and of the on-farm hygiene practices in place. Staff induction should include the cleaning process of footwear and equipment on entering and exiting to property.
- A footbath should be installed at the entry to the orchard and used every time staff work in that area. Footwear needs to be re-cleaned if moving in and out of the truffle orchard. Other options are to provide footwear that is to worn on the farm only and not taken off site and is preferably left at the entrance to the orchard, or use disposable overshoes. Clothing should also be clean/dirt free.
- When using footbaths the sanitising solution should be changed at least daily. Footwear needs to be free of all soil and organic matter before being sanitised.
- Dogs feet should also be cleaned if they are being moved between multiple orchards. Or they can be provided with booties.
- Use an orchard vehicle, not external vehicle, for the transport of visitors around the property.
Vehicles, machinery, tools and equipment
Best practice is to minimise the movement in and out of the orchard. All non-essential vehicles should stay out of production areas of the farm. Around the property use designated road ways for vehicles to reduce the amount of traffic in production areas. Only drive in paddocks when necessary and particularly avoid driving in production areas in wet, muddy conditions. Restricted areas should be signed and if necessary locked and if you do have a high risk area consider having specific equipment designated to that area.
Farm machinery including tractors, mowers, spreaders and sprayers should be washed down prior to entry into the orchard. This is particularly important for vehicles and equipment that visit others properties such as contractor vehicles.
It is preferred to have a designated wash-down bay for vehicles. It should have high pressure water and/or air for cleaning. Ideally a wash-down site is located between the driveway and farm roads for easy access when entering and exiting the property, is a sealed pad or compacted gravel and directs run-off away from production areas.
When washing down a vehicle wash from the top down. Take particular note of tyres and wheel arches, grills, undercarriage, ute trays and floors. Wash then disinfect. It is also good practice to regularly wash on site vehicles as well.
Tools and equipment such as pruning saws, secateurs and hand trowels should also be cleaned regularly.
The management practices listed below not only help to prevent unwanted soil and plant material entering your property they also ensure you are well placed to quickly identify any new pest or disease problems.
- Ensure your propagation material is pest status known given current technology, record the source and, preferably have your trees evaluated by the Australian Truffle Growers Association certification scheme.
- Remove weeds and volunteer plants that could act as alternate hosts and harbour unwanted mycorrhiza, pests and/or diseases.
- Minimise water runoff and soil water erosion that can carry soil around site.
- Conduct regular crop surveillance to pick up trouble spots and incursions.
Animals, either livestock or wildlife, can introduce contaminate fungi and pests and diseases into an orchard.
- Regularly check and maintain fences. The standard of fencing will largely be dependent on the expected level of pressure from animals namely, kangaroos, pigs and rabbits.
- Prevent livestock movement in the truffle orchard.
- If necessary implement a feral animal control program. You may need to work with neighbours to co-ordinate feral animal control.
De Miguel, AM, Agueda, B, Sánchez, S, Parladé, J 2014, ‘Ectomycorrhizal fungus diversity and community structure with natural and cultivated truffle hosts: applying lessons learned to future truffle culture’, Mycorrhiza, Volume 24, Supplement 1, pp 5-18