In this article from Vegetables Australia magazine, AUSVEG Biosecurity Adviser Dr Kevin Clayton-Greene discusses how a robust on-farm biosecurity system can protect Australian vegetable growing operations from the threat of pests and diseases, particularly those that seem inevitable to spread or arrive on our shores.
I have heard it often said that it is inevitable that pest ‘X’ will arrive. This is particularly true in discussions around the tomato-potato psyllid; the wisdom being that it will make it to the east. I don’t necessarily subscribe to this view. While it is prudent to prepare for this eventuality, it is not inevitable and the use of this phrase can lead to a self-fulfilling prophecy.
Although some things such as death are inevitable, most are not, particularly those that are human-mediated. However, if we adopt the position that an event is inevitable human behaviour, it suggests that we will automatically become less careful about prevention. Alongside this, many also despair at the apparent lack of interest among the public about biosecurity, adding to the feeling of ‘inevitability’.
There are many things we can do to prevent so-called inevitable occurrences and in this month’s article I want to look at this in the context of on-farm biosecurity. This topic has a particular resonance with vegetable and potato production due to the relationship between soilborne pathogens and pack out.
Controlling the threat of disease
In Australia and elsewhere in the world, there have been tens of millions of dollars expended on soil disease research on a number of what I would term ‘intractable’ soilborne diseases such as powdery scab, Fusarium and Rhizoctonia species. While we have made great strides in our understanding and detection of these diseases, it is also true that their control remains problematic.
In the case of powdery scab in potato, this disease (once found) persists for a very long time in the soil and is something that no-one wishes to introduce onto their property.
Furthermore, it is not just bacteria and fungi that can persist in soil, but many viruses also have this ability. As producers we are on the front line of trying to control these threats to our livelihood, but we are also pitting ourselves against millions of years of evolution that has equipped these pathogens and pests with very sophisticated breeding systems to help overcome barriers to their existence.
This manifests itself in resistance to plant protection products and the ability to exploit new hosts when these pests are introduced into a new region or country.
So what does all this have to do with biosecurity?
As producers, we have limited or no control over what happens in the broader community: however, we do have complete control over what happens on our property and also what enters and leaves it via human activity. This is where on-farm biosecurity is important and also one of the ‘cornerstones’ of a robust biosecurity system.
Curative and prophylactic control of pests or pathogens can be a significant cost and every new pest adds to that burden. It is true that having a good on-farm biosecurity system has a cost, but it is also true that, in most cases, this is repaid by lower pest and disease input costs.
Good on-farm biosecurity can greatly reduce the potential for the introduction of new pests and diseases from elsewhere, but it can also significantly reduce pest pathogen pressure by removing reservoirs of pests. Many weed species proliferate because they are closely related to the cropping species and therefore have the same or similar herbicide profiles as the crop (eg nightshade and potatoes, wild radish and other brassicas). Persistence of these weeds will ensure there is a ready source of disease or pests for the next time a closely-related crop is planted, ensuring the ‘inevitability’ of re-infection.
Similarly, vehicles and people entering the farm or moving around carry a host of diseases on their surfaces. By implementing biosecurity on our properties which will interact with all visitors, we can also greatly increase awareness among not only our peers but also others such as contractors; friends and family; transport operators; utility providers etc. This can only have a broader beneficial impact by raising general awareness of biosecurity as well as improving our own circumstances.