Hi, welcome to Taiga Bonsai, in this article we continue our discussion on ‘Plant husbandry’ dealing with more harmful pests and disease.

Introduction – during World War II (1939 – 1945) many governments mandated that more produce be grown to feed those at the front line and rationing was introduced which lasted until 1954. Meadows and wildlife havens were turned into arable land and although the effects of this were not apparent at the time; it was the beginning of the end for the bug world.

The birth of the EEC – on March 25th, 1957 France, West Germany, Italy, the Netherlands, Belgium and Luxembourg signed the Rome treaty establishing the European Economic Community (EEC), also known as the Common Market. Later other countries joined and soon there was an abundance of food.

This excess including butter mountains, milk and wine lakes, gluts of potatoes, apples and other crops could have been given away to the poor, or countries facing drought and famine. Instead what could not be poured away was disposed of in disused mine shafts. The politicians and agricultural heads wanted to maintain ‘economic stability’ – ‘nothing is for free’.

The green and pleasant lands are now a bygone era, forests have and are being cut down. An area the size of Wales 20,779 km² (a country in southwest UK) is being removed on a daily basis in the Amazon.

The meadows that existed are now under housing estates, rivers are polluted and the air quality is deteriorating. The friendly bugs have gone and it is doubtful they will return. The crop harvests GMO or organic will devastated by marauding invaders many whom are immune to pest control.

A never ending battle – according to CABI News digital library (09 February 2022) they conclude there are approximately 73,000 different tree species on Earth, of which around 9,000 are thought to be undiscovered. In addition, there exist more than 80,000 known plant diseases worldwide.

All plants are vulnerable to attack by disease, including crop plants which are frequent victims. The result is enormous agricultural, horticultural and economic loss. Now due to the relaxed regulations pest and disease are able to infect countries that were free of this devastation.  

The problem with disease – is that it cannot in reality be detected until there is visible evidence, by insect damage or that of fungi. Science has told us that microorganisms can exist in a single-cell form or a colony like bacteria and fungi. Although they are often associated with dirt and disease, most microbes are beneficial. But as we are aware there exist those microbes, fungi and pathogens that have lethal potential; here a few examples.

Armillaria mellea is a parasitic fungus doing immense damage to forests, it attacks both coniferous and deciduous species. By the time the fruit bodies are in evidence, the damage done internally is usually so great that the tree is doomed.

It is widespread in northern temperate zones including North America, Europe, Northern Asia and in South Africa. Trees that are attacked become parasitized. The foliage becomes sparse and discoloured, twig growth slows down and branches die back. There are no known fungicides or management practices that can kill Armillaria mellea after infection without damaging the infected plant.

Canker is a small area of dead tissue, which grows slowly, some of these are of only minor consequence, but others are ultimately lethal and therefore, can have major economic implications for agriculture and horticulture.

They are caused by a wide range of organisms including fungi, bacteria, mycoplasmas and viruses. The majority of canker-causing organisms are bound to a unique host species or genus, but a few will attack other plants. Fungicides or bactericides can treat some cankers, often the only available treatment is to destroy the infected plant to contain the disease. The Butternut canker (shown below) is a lethal disease affecting Butternut trees for which there is no cure.

This is a deadly bacteria that attacks economically important crops such as olive, citrus, plum trees and grapevines. Since 2015, it’s been rapidly spreading from the Americas to Europe and Asia. Once the disease infiltrates a plant, it is there to stay, it starves the plant of water until the plant dies or becomes too weak to grow fruit. 

Xylella fastidiosa – is another deadly disease the bacterium (shown below)

X. fastidiosa costs $104 million per year in wine losses in California and in Italy. The bacteria has led to the decline of 180,000 hectares of olive groves destroying many centuries-old trees; a loss of €390 million over three years. X. fastidiosa constitutes a threat not only to Italy but to all the Mediterranean region’s economy.

X. fastidiosa is not known to be in the UK however, there have been outbreaks of the disease in mainland Europe in France, Italy and Spain. Portugal confirmed its first case in 2019 on lavender.

The UK Government is concerned about how to prevent the disease being accidentally brought into the country on imported plants. In 2020 Lord Framlingham a Conservative peer asked the Government what the UK’s regulations are regarding X. fastidiosa.

UK regulations were to introduce measures to strengthen the protection of plants from certain pests and diseases, including Xylella. They were made under article 52 of the EU Plant Health Regulation, allowing the UK to take additional temporary national measures. Providing they inform the European Commission and put forward a technical case to request EU measures against a specific pest.

However, those measures have not or will not be introduced in time to mitigate the risk concerned. Moreover, the UK Government has argued that current EU emergency measures on Xylella, do not address risks highlighted in the UK’s pest risk analysis on the disease.

In particular, it is not clear if or when the EU emergency measures will be reviewed to address these risks and ensure a greater degree of assurance of disease freedom, in relation to plants of those species being moved in the EU and introduced from third countries.

As such, there remains an unacceptable level of pest risk and this instrument introduces national measures under article 52, in the absence of EU requirements.

Verticillium– is a genus of fungi in the division Ascomycota, which is an anamorphic form of the family Plectosphaerellaceae. The genus used to include diverse groups comprising saprobes and parasites of higher plants, insects, nematodes, mollusc eggs and other fungi.

The genus, currently thought to contain 51 species, may broadly be divided into three ecologically based groups – mycopathogens, entomopathogens, plant pathogens and related saprotrophs. At least five species are known to cause a wilt disease in plants called verticillium wilt: V. dahliae, V. longisporum, V. albo-atrum, V. nubilum, and V. tricorpus. A sixth species, V. theobromae, causes fruit or crown rot, a non-wilting disease.

Verticillium wilt is a disease that can affect over 400 different plants and trees, many of which are economically important worldwide. Several characteristics of Verticillium make it difficult to manage: prolonged survival in soils without the presence of a host plant.

The fungus survives in the soil principally in the form of microsclerotia and invades the plant through the root system, colonising the vasculature eventually leading to plants demise.

The main mechanisms of it’s pathogenesis are xylem vessel blockage and toxin production. When the fungus propagates within a host plant, the mycelium blocks the xylem vessels, impairing the transport of water and nutrients in the host.

Thus forces of transpiration and respiration in leaves combined with blocked xylem transport, cause water imbalances in leaves that result in leaf yellowing and wilting, contributing to plant death.

In addition, Verticillium produces mycotoxins within the plant that can cause necrosis in leaves and impair metabolism in the plant’s body. In some systems, toxin production has been shown to be the main cause of plant wilting.

The diseases discussed here (Armillaria mellea, Butternut canker, Xylella fastidiosa and Verticillium) are very serious not to be taken lightly, they can infect other plant types within the vicinity. However, there are many more to be found within the 80,000 diseases that we know of. In the next article we look at the borers, until next time, BW, Nik.

Hi welcome to Taiga Bonzai, in this post we look at the points of view of others whom have various opinions on how to tackle the ever increasing problem of pests and disease. However, the course of action taken by individuals, communities and/or sovereign nations, results in stiff opposition and the threat of sanctions. Due to bureaucracy and petty mindedness.

Introduction – thus far we have highlighted the many factors responsible for the present situation, that we now face all of which are of our own making. The financial cost of it all to date has been phenomenal and will continue to rise exponentially. Meeting our own needs without compromising the ability of future generations, will be difficult; bringing us to the point of no return.

United Nations FAO – at a conference in Rome 3rd April 2019, Bukar Tijani assistant director general for the Food and Agriculture Organisation of the United Nations (FAO) Consumer Protection Department stated that. “With increased trade and travel, the risks of plant pests spreading into new areas across borders is now higher than ever before. Each day we witness a shocking number of threats to the well-being of our plants and by extension to our health, environment and economy.”

The FAO estimates that annually between 20 to 40 percent of global crop production is lost to pests. Each year plant diseases cost the global economy around $220 billion and invasive insects around $70 billion. “Many farmers and governments grapple with warding off highly destructive pests and diseases that are – on top of everything else – also new to them. The International Plant Protection Convention IPPC provides them with the tools and knowledge to keep their plants healthy and prevent pests from jumping borders.” added Tijani.

New IPPC standards adopted – 1. fumigation methods, this is in response to growing concerns over fumigants that can be harmful to human health and the environment. The standard requirements for temperature, duration, fumigants and quantity have been set.

2. Diagnostics protocols that describe procedures and methods for the official diagnosis of six pests. Including the oriental fruit fly Bactrocera dorsalis and Xylella fastidiosa, ensuring a correct diagnosis is essential to catalyse rapid actions to manage the pests.

B. dorsalis has affected trees such as avocado, banana, guava and mango in at least 65 countries. In Africa, import trade bans due to oriental fruit fly infestations cause annual losses of around $2 billion. Xylella fastidiosa is a deadly bacteria that attacks economically important crops such as olive, citrus, plum trees and grapevines.

Since 2015, it’s been rapidly spreading from the Americas to Europe and Asia. Once the disease infiltrates a plant, it is there to stay, it starves the plant of water until the plant dies or becomes too weak to grow fruit.

X. fastidiosa costs $104 million per year in wine losses in California and in Italy the bacteria has led to the decline of 180,000 hectares of olive groves, destroying many centuries-old trees. A loss of €390 million over three years. X. fastidiosa constitutes a threat not only to Italy but to all the Mediterranean region’s economy.

X. fastidiosa is not known to be in the UK however, there have been outbreaks of the disease in mainland Europe in France, Italy and Spain. Portugal confirmed its first case in 2019 on lavender. Hence, the UK Government is concerned on how to prevent the disease being accidentally brought into the country on imported plants. In 2020 Lord Framlingham a Conservative peer asked the Government what the UK’s regulations are regarding X. fastidiosa.

UK regulations – measures were to strengthen the protection of plants from certain pests and diseases, including Xylella. They were made under article 52 of the EU Plant Health Regulation. Allowing the UK to take additional temporary national measures, providing they inform the European Commission and put forward a technical case to request EU measures against a specific pest. But those measures have not or will not be introduced in time to mitigate the risk concerned.

Moreover, the UK Government has argued that current EU emergency measures on Xylella do not address risks highlighted in the UK’s pest risk analysis on the disease.

In particular, it is not clear if or when the EU emergency measures will be reviewed to address these risks and ensure a greater degree of assurance of disease freedom. In relation to plants of those species being moved in the EU and introduced from third countries. As such, there remains an unacceptable level of pest risk and this instrument introduces national measures under article 52, in the absence of EU requirements.

The European Commission’s response – on 4 June 2020, the EU said that it informed the UK the new national measures. “That go beyond the existing requirements, are not supported by most recent scientific justification and are disproportionate.” It stated that the UK “should amend it’s official control regulations of 2019, by removing the amendments concerning X. fastidiosa and Ceratocystis platani which were made to those regulations by the UK in 2020.”

On 19 June 2020, Department for Environment, Food and Rural Affairs (Defra) stated that the UK disagreed with the European Commission’s conclusions and that it was disappointed. “The opportunity has not been taken to extend the UK measures across the EU, providing enhanced protections for the EU’s member states.” Defra argued “that the biosecurity threat regarding the pests had not changed and the rationale for introducing stronger requirements remained.”

The department said it continued to encourage stakeholders and industry to “employ risk management practices which maintain the robust protection and assurance that the Defra regulations provide.” 

Defra also stated that The Animal and Plant Health Agency and the devolved administrations will continue to carry out intensive inspections of imported plants. Taking account of risk factors such as origin, presence of insect vectors and suspect symptoms. “We will keep the need for any further actions under review in light of the ongoing risk situation, including developments in the EU and the results of our own surveillance.”

The Royal Horticulture Society (RHS) is also in agreement, plant health is increasingly under threat. Climate change and human activities have altered ecosystems, reducing biodiversity and creating new niches where pests and diseases can thrive. At the same time, international travel and trade has tripled in volume in the last decade. The result is that pests and diseases can quickly spread around the world causing great damage to horticulture, crops and the environment.

New statutory controls on importing plants and plant products into the UK to safeguard plant health. “Meaning that plant material entering the UK will require a phytosanitary certificate (PC); the EU plant passport is no longer valid in the UK.” 

The U.S. DEPARTMENT OF AGRICULTURE – (USDA) state that world trade has significantly increased over the years to meet the growing demand and at this moment in time, America is the only country to import more than it exports.

USDA researchers Michael Livingston, Craig Osteen and Donna Roberts argue “That this increase in agricultural imports raise the risk of inadvertently introducing foreign pests and diseases.” which has been proven to be the case. For example, the emerald ash borer and Asian long horned beetle introduced in the 1990’s are creating serious damage to trees in the Northeast and Great Lakes States.

More recently Ralstonia solanacearum, a bacterial pathogen that damages potatoes, eggplant, tomatoes and other horticultural products was detected on greenhouse geraniums imported from Kenya and Guatemala. “The cost of foreign pests and diseases can also include the temporary loss of export markets, such as when Japan, Korea and other countries suspended imports of U.S. beef when bovine spongiform encephalopathy (BSE) was detected in an imported cow in December 2003.”

Studies by the National Plant Board, the Government Accountability Office, the Office of Technology Assessment and others, report that foreign pests and diseases cause billions of dollars of economic losses to U.S. agriculture each year, while also adversely affecting ecosystem values and services.

These cost estimates include sizable public expenditures, including emergency funding to address new pest or disease threats and outbreaks. Today, 21 Federal agencies are responsible for some aspect of managing foreign pests and diseases in the United States.

USDA’s Animal and Plant Health Inspection Service (APHIS) has by far, the leading role accounting for about $9 out of every $10 that the Federal Government spends annually on prevention and control of foreign pests and diseases. Annual expenditures for APHIS programs ranged from $1.1 to $1.5 billion between 2003 and 2007, including emergency expenditures for programs such as increased BSE surveillance in 2004-06 and the introduction of import bans.

In evaluating such bans, economists try to measure the benefits of imports against the management production market and/or resource costs that might be associated with an outbreak of a disease or pest. Studies show that this varies on a case-by-case basis. Import bans have reduced total welfare in some cases, because the cost of disease establishment was out weighed by the consumer benefits from imports.

For example, APHIS estimated that the annual net benefits of replacing a long standing ban on imports of Mexican avocados with more targeted phytosanitary measures totalled about $70 million. Providing analysis support for USDA’s decision to grant Mexico full access to the U.S. market in 2007.

A recent study by an ERS economist, which examined options for policies to reduce the risk of entry of the Mediterranean fruit fly, (medfly) illustrates how economic analysis can inform public decision making. The medfly is a serious pest for many fruit and vegetable crops and is known to exist in 65 foreign countries. (hereafter referred to as quarantine countries)

APHIS allows imports of fresh produce from these countries only if they have been treated to eliminate medfly larvae. Currently, eight treatments are approved for the medfly. One of the most widely used is cold treatment, under which produce imported for fresh consumption must be refrigerated according to specific schedules (temperature-duration combinations) before allowed entry into U.S. markets.

In the next article we look at how other nations are dealing with the problems of pests and disease. Until next time, BW, Nik.