Preventing Exotic Pathogen Threats to Forests - A Sideways Scientific Look
Clive Brasier1
We have a prevention system that is
- Systematic
- International
- Well regulated and policed
Nonetheless, Sudden Oak Death is just another symptom of a historical problem
- Although the current system of prevention is often excellently and expertly carried out by regulatory agencies - The system cannot succeed, because it is not yet properly science based.
Biological weaknesses
- List dependent. Essentially a list system derived from 'Noahs ark' and from Linnaean systematics and routinely based on the morphospecies (pathogen looks like x - therefore it is x), not the species and genotypes of modern population biology. Leaves both legal and identification loopholes.
- Non Darwinian. Not yet caught up with 1850s science. Evolutionary theory warns us that the greatest threat is from organisms that have evolved in 'other' biogeographical zones, but have not yet escaped and so are still 'waiting' to cause serious damage on new hosts. These threats need to be anticipated.
- Reactive not proactive. The present schedules, however, tend to cover mainly those pathogens that have already escaped outside their original evolutionary zone and are already causing noticeable damage on new (non co-evolved) hosts as they spread (DED, Chestnut blight, Pinewood nematode, Plane wilt, Cypress canker, Dogwood anthracnose...).
- Structural rigidity. Present system, being largely list not process driven, may lack the flexibility to embrace major new risk processes related to or even arising directly from it, including:
- Trojan horse syndrome: Fungistatic compounds widely used by plant trade temporarily mask disease symptoms on exported stock. Promotes effective spread of exotic pathogens (SOD? Includes many exotic Phytophthoras).
- Typhoid Mary syndrome: Non-host carriers. Organisms threatening to forests are exported on apparently innocuous plant 'carriers'. (cf Rhododendrons and SOD). A classic Darwinian scenario (no evolved resistance in the threatened tree hosts)
- Hybridisation syndrome: Rapid evolution of new hybrid pathogens and new diseases is promoted by the present trade structure. These hybrids are neither detected, nor properly covered by the current system.
Our present system of prevention therefore tends to respond to the ripples after a splash and not prevent the splash.
Result is that probably only 10-20% of the exotic pathogens that threaten our forests are covered in the schedules.
Market forces and policy
- Weakest link. Within multi-state ecopoltical units such as the EU, the system may operate at the level of weakest state, which promotes risk. This is the very antithesis of how living organisms evolved to restrict the spread of diseases via multiple compartments or 'fire walls' ie it is a non-Darwinian structure.
- Non-Keynesian. System not 'responsible economics' based. Lacks central environmental Keynesian principle that 'polluter pay'. Therefore- no feedback loop on the economic or the regulatory system.
- Institutionalisation. A lack of market pressure in favour of progressive and sustainable bioprotection policy can allow markets and regulators to become entrenched and conservative. Become part of the problem, not part of the solution? (Fisheries protection issues come to mind)
- Nelsonian approach. A consequence of defensiveness from regulators over unspoken weaknesses of a system can be resistance to policy changes and to strategic thinking. And resistance to funding of research that could further expose the weaknesses. Better - inaction or avoidance: "I see no risks..."
Presently, market forces don't operate directly on Governments, regulators or commerce to ensure support for effective forest bioprotection measures. The result is nobody pays, for example, for recent disasters such as Dutch elm disease or the current alder mortality. Or rather, only the public and the environment are paying, long term.
Diagnosis--
A scientific health check indicates the present prevention system itself is a threat.
Treatment?
Evolutionary biology - 1850s science - argues that the present system needs to be better balanced and in parts reversed:
- More science process led. Both economics and bioscience.
- Proactive approach. Identify and test the risk levels of pathogens in their centres of origin before they escape. Modern technology and infrastructure can allow us to do this. Needs international Rio-style agreements.
- Fully apply precautionary principle. Significantly reduce the risk from plant imports by:
- Regulating plant introductions like animal introductions
- Importing only meristem cultures or seed
- Encouraging local propagation of forest trees, shrubs and ornamentals
- Update Noah. Routinely apply risk protocols to pathogen genotypes, varieties and unnamed taxa as well as to morphospecies.
- "Liberté, egalité..." Develop regular and periodic policy review systems: science based, open to changes in scientific knowledge, responsive to informed criticism, open to public debate.
Effective intelligence.
Protecting forests from exotics is a never-ending war.
And, if recent processes continue, losses on the horizon may be large.
There are many parallels to the 'war on terrorism'. We must always be two steps ahead of the enemy.
Effective intelligence and scientific insight are our first line of defence.
Globally and locally correct regulatory protocols, based on these insights, are our second.
1Emeritus Mycologist, Forest Research Agency, Farnham, Surrey GU10 4LH, UK; clive.brasier@forestry.gsi.gov.uk
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