Farm biosecurity improves the management of soil-borne diseases

Staff from the Victorian Strawberry Industry Certification Authority (VSICA) inspecting strawberry runners for pests and diseases. Photo credit: VSICA

Disease causing organisms found in the soil can be very difficult and expensive to control or eradicate. For many, once they are on a farm, they are there to stay.

Producers are often advised to use biosecurity practices to minimise the risks posed by pests and diseases that are found in soil. But how do you know if they work?

Researchers* recently surveyed growers to find out how effective biosecurity practices were at controlling a soil-borne disease of strawberry.

Although the results are for one disease on one crop, they clearly demonstrate the benefits to be had from using simple biosecurity measures on your farm.

Importance of soil borne diseases in strawberry

Soil-borne pathogens cause diseases that stunt and/or kill strawberry plants. They are widespread across the globe and cause severe economic losses each year.

In Australia, charcoal rot, Fusarium wilt and Phytophthora crown rot are some of the most devastating soil-borne diseases of strawberry and have increased in importance since the phase-out of the fumigant methyl bromide. Based on a survey of the Victorian strawberry industry in 2020, charcoal rot killed 15 per cent of plants and cost the industry $15 million.

Association between the number biosecurity practices (out of 11) adopted by strawberry growers on their farms in Victoria in 2020-21 and the incidence of charcoal rot in their crop. Note: no growers had adopted fewer than five of the eleven farm biosecurity practices.

Do farm biosecurity practices really help manage disease?

In 2020–21, the researchers surveyed 77 strawberry growers in Victoria about their farm biosecurity practices. They then measured the incidence of charcoal rot and the amount of the fungus Macrophomina phaseolina that causes the disease on their properties.

Results showed there was a strong association between the number of farm biosecurity practices used by growers and charcoal rot in their crops. Growers who used more practices had less M. phaseolina and charcoal rot.

Benefits across the industry

Charcoal rot had also decreased by 20 per cent across Victorian strawberry farms in 2020–21, compared with 2017.

The researchers suggest that as more strawberry growers adopt more biosecurity practices, there will be less spread of diseases, pests and weeds across the industry.

So, what were the strawberry farmers doing?

The strawberry growers were using the following biosecurity practices:

• Planting Certified strawberry runners
  Certified runners give strawberry plants the healthiest start possible because they are inspected for pests and diseases before they arrive at your property.
• Erecting biosecurity signs
  Biosecurity signs indicate to the public and staff that growers are serious about maintaining high standards of hygiene. Be sure to include a phone number on these signs so that visitors can contact you before they enter your property.
• Minimising property entry
  Minimising entry points onto a strawberry property gives growers greater control over who is coming onto their property. Limit the number of access points to your property (e.g. lock unused gates and construct fences).
• Using designated car parks
  

  Growers cleaning a tractor with high pressure water to remove soil, in a designated washdown location. Photo credit: VSICA

  Limiting vehicles to designated areas on your property helps to contain any infested soil they may carry. Car parks can also help to control the movement of visitors and staff on your property.

• Washing down vehicles
  All vehicles should be cleaned before they enter your property. It is important to routinely washdown your work vehicles (e.g. tractors) between paddocks especially when they move from a paddock with high disease into a paddock with low disease. Pay attention to car tyres, grills and wheel rims when cleaning vehicles.
• Staff and visitor hygiene
  Provide appropriate hand and shoe washing facilities for employees and visitors to use while they are on your farm to remove soil.
• Property zoning
  Dividing your farm into production, packing and visitor areas will allow you to define where individuals may or may not go.
• Paddock zoning
  Conduct your farm operations (eg spraying, picking, etc.) from paddocks with low disease towards paddocks with high disease. This minimises the risk of workers and farm vehicles carrying infested soil to areas of low disease. You can determine which paddocks have high or low disease from your farm records or by getting the soil analysed for pathogens that cause disease. Paddock zoning will enable you to reduce the spread of disease across your property.
• Removing old and/or dead planting material
  Infected strawberry crowns in soil (dead plants from the previous season) can harbour pathogens. Therefore, if feasible, you should remove dead and/ or old strawberry plants from your production sites and destroy them elsewhere.
• Cleaning equipment
  Farm equipment (eg picking trays) may collect and spread infested soil and plant debris. All farm equipment should be cleaned regularly, especially those moving between paddocks.
• Training staff
  Induct your staff and visitors in farm biosecurity. Give clear directions regarding the biosecurity practices you require them to perform on your property.

* Dr Dylan McFarlane and Dr Scott Mattner of VSICA Research and Yilin He from YunNan LuFeng QuinPan Agri-Dev. Co.

Acknowledgements

Edited, with permission, from an article that originally appeared on page 81 of Edition 7, Winter 2021, of the Australian Berry Journal.

The authors acknowledge funds from the Australian Government, VSICA Research Pty Ltd and YunNan LuFeng QuinPan Agri-Dev. Co. Ltd to support collaborations between Australian and Chinese businesses. They thank the strawberry fruit growers in Australia and China for providing plant and/or soil samples, and their time.