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Biosecurity – What’s in it for me or why should I bother?

Biosecurity

For Australian Fruitgrower magazine APAL Technical Manager Rose Daniel and biosecurity expert Dr. Kevin Clayton-Greene explore what happens when a hypothetical plant pest enters Australia, and how that might impact on the Australian apple and pear industry.

Learnings from COVID-19

We have learned from the COVID-19 pandemic that our actions and those of others are connected and play an important role in disease management. Movement restrictions in the COVID-19 emergency are in place because our actions impact upon others. In Australia, these restrictions have been incredibly effective in helping to stop the coronavirus from spreading and in reducing people’s exposure to it. COVID-19 is caused by a virus and is abiosecurity matter, which means that many of the actions taken by governments are covered by the powers invested in them through the same biosecurity legislation that governs plant biosecurity. Although other recent disasters such as the bushfires and drought, are not caused by biological organisms, their impact and management have a number of commonalities from which we can learn when dealing with a biosecurity incursion. The bushfires have destroyed or taken out of production many orchards. During the bushfires property identification was difficult in a number of instances. Post fires, the ability to source and utilise relief packages for the industry has required considerable effort in understanding production costs for individuals. Compensation requires accurate data upon which to base any financial relief as the money provided is subject to audit.

The impact of the drought raised similar issues. The points highlighted above all come into play during an incursion by an exotic pest (here pests include fungi, bacteria, nematodes, viruses as well
as insects and weeds). While there are many threats and risks with which any producer may have to cope, biosecurity is one of the few that has the potential to destroy or severely limit an industry sector. Current examples around the world include Xylella fastidiosa affecting the olive industry in Italy and Spain, Brown Marmorated Stink Bug upon pear producers in northern Italy, Drosophila suzukii and the soft fruit industry in the UK, glassy winged sharp-shooter and Pierce’s disease in grapes and citrus greening (Huanglongbing disease) and Asian citrus psyllids in Florida. In each of these instances horticultural production in the affected areas is under severe stress and declining significantly due to either the inability to control the disease, or the cost of control. You may also remember when Fireblight (Erwinia amylovora) was reported in Melbourne in 1997? The important thing is that unlike the natural disasters mentioned above, biosecurity is something over which our industry can at least have some element of control, by being prepared and developing risk mitigation strategies.

The coronavirus has had a devastating effect upon human movement, trade and, although food is regarded as an essential service, the availability of transport and access has had a big impact upon distribution, particularly interstate and export movements. Depending upon what it is, the incursion of a plant pest will have an impact upon the individual, others around the initial affected site and potentially the wider industry through trade restriction(s). To illustrate the latter, we need only look at the recent incursion in 2017 of tomato potato psyllid (TPP) in Western Australia. This insect pest only directly affects Solanaceous crops such as potatoes, tomatoes, capsicums, tamarillos and eggplant. However, in the initial phase of the incursion more than 60 crop species were affected by trade embargos upon produce from the affected area(s). These crops ranged from broccoli through apples to strawberries and nursery stock.

(Credit: Southwest Montana Science Partnership).

This diagram may look familiar. One of the reasons that Australia has so effectively reduced the number of cases of COVID-19 in the general population is because of the early and far-reaching implementation of social distancing.

This can be seen in an invasion curve such as the one below – the earlier that control measures are put into place, the more likely it is that these control measures will be effective, and the impacts of the pest or disease are reduced. A similar situation exists for plant pests – the earlier an exotic pest is detected and confirmed, the less chance it has
to reproduce and spread. Just as we are working toward ‘flattening the curve’ to manage COVID-19, we would also aim to reduce the curve in the event of a plant pest incursion.

The invasion curve shows a generalised response in a pest population over time, after the introduction and establishment of a new invasive species into a new environment. As the pest population increases and spreads, the chances of detecting that pest increase, but it also becomes more difficult to eradicate that pest population. As the pest population becomes established the management costs also increase.

As we write this article the world is facing one of the worst health and economic crises it has encountered since the Spanish Flu pandemic of the early 1900s infected an estimated 500 million people and killed as many as 50 million globally. Just as Australia was affected by Spanish Flu, Australia is also part of this current emergency.

Coronavirus, or COVID-19, comes directly on top of the devastating drought experienced in many regions and the 2019–20 bushfires which afflicted wide areas of the country, particularly the eastern seaboard, including many horticultural producers. So, what do all these ‘emergencies’ have to do with biosecurity and APAL members? Quite a lot as it happens.

Losses in citrus

Since Huonglongbing (HLB) was discovered in Florida in 2005 citrus production has declined by more than 70 per cent. Between 2002 and 2017 the number of citrus growers in the state decreased by more than 30 per cent, the number of juice processing facilities by more than 30 per cent and the number of packing sheds also by more than 30 per cent (Singerman et al. 2020). The industry has been downsizing as a result of massive losses. HLB is regarded as the most devastating citrus disease worldwide.

The disease, caused by the bacterium Candidatus Liberibacter asiaticus, is spread by the citrus psyllid, Diaphorina citri. The psyllids fly between trees, feed on leaves and leave behind the bacteria that interfere with the tree’s ability to transport water and nutrients. Trees are less productive. Fruit is misshapen, discoloured, smaller (right side fruit in image) and unsaleable. Once a tree is infected, there is no cure and it typically dies within a few
years. Many orchards have been pulled out.

Photos: Nerida Donovan, NSW Department of Primary Industries

Photos: Nerida Donovan, NSW Department of Primary Industries

Beware knock-on effect

Because TPP had been reported on these plants in the published literature and there was concern amongst regulators and producers in other parts of Australia that TPP could be transported as a passenger on these crops, therefore trade was stopped. It took several months for this to be sorted out!

We can minimise the impact of future incursions by learning from the TPP experience that:

1. Knowing how the biosecurity system operates, even for individual producers, would have saved a lot of misinformation and unnecessary angst amongst those affected and ensured better
business continuity.

2. Accurate record keeping is essential for claiming Owner Reimbursement Costs.

3. Understanding how trade and regulation operates is important so that we can prepared for any new incursion.

4. Knowing where producers are and what they grow is vital in managing an outbreak.

5. Regulators need to know, quickly, how and what the standard industry practices are when determining control measures.

6. Scientific research data and evidence is important in driving accurate decision making.

7. Regional industry personnel need to be trained to perform their functions as part of any response.

8. Emergency responses although run by the ‘host state’ are national and that decisions are made with both national and regional interests having to be considered.

9. The social and personal cost to affected individuals can be very high and that people involved need support.

10. Even if the pest is not a problem for the crop you grow you may still be affected.

The last point is important because most pome fruit production occurs in the vicinity of other horticultural crops, such as berries and stonefruit and thus incursions in these crops may also have an impact and vice-versa. APAL is in the process of developing a Biosecurity Framework and is investing in developing capability and preparedness to ensure that the industry is well prepared to meet future biosecurity threats throughout the whole industry. As part of this strategy we will follow a hypothetical incursion to see how the various pieces fit together and address the important points listed above. The next article will look at the first phase of an incursion for one of the apple and pear industry’s high priority pests, what happens, and who is involved.

Brown marmorated stink bug is one of a number of high priority exotic pests of apples and pears threatening our
biosecurity. Photo: Gary Bernon, USDA, APHIS, Bugwood.org.

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