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 share some of the comments we have received regarding the articles ‘Unseen invasion’.

Introduction – the viewpoints of our readers are many and varied with all having concerns on the ever increasing problem of pests and disease that are threatening our very existence. But to discuss them all at length would make this article far too long therefore, we will take a small selection 10 in total in reverse order and we thank all whom have commented on our articles. In addition, there were also questions that will be answered at the end.

• 10. Amy Hardcastle – “I had heard of the problem with declining insect populations but I did not realise the situation was so severe, I do now! Thank you.”
• 9. Leon Sanchez – “Your posts Unseen Invasion: ‘Portugal confirmed its first case in 2019 on lavender’ certainly shows the severity of the problem with the deadly disease Xylella fastidiosa, congrats.”
• 8. Gillian P. Simmonds – “Taiga bonzai certainly knows how to get people’s attention on topics that most fail to understand, we do have problems and I do agree they need to be addressed, please keep writing.”
• 7. Jonas Olsson – “Great work, you have given the powers that be a strong clear message will they listen! I sincerely hope they do otherwise we will be in serious trouble.”
• 6. Lilian Gough – “Many bloggers write good work but yours is on another level, your work is artistic informative and a pleasure to read if only there were more like you.”
• 5. Heinz Muller – “Unseen invasion really drive the message home here’s hoping the bureaucrats take note, very good articles.”
• 4. Andrew Billings – “Talent is a hard to find in these days especially on subjects such as yours – you are able to get the message across, enjoyable reading, I look forward to more.”
• 3. Galen Jonak – “It’s hard to come by well-informed people on this topic however, you seem like you know what you’re talking about! Thanks”
• 2. Taren Vanlier – “May I simply say what a relief to uncover a person that really understands what they are talking about on the internet. You actually know how to bring an issue to light and make it important. A lot more people really need to check this out and understand this side of the story. I can’t believe you’re not more popular given that you certainly possess the gift.”
• 1. Dalton Beitz – “I’m amazed, I must say. Seldom do I come across a blog that’s both educative and entertaining and without a doubt, you have hit the nail on the head. The issue is an issue that not enough men and women are speaking intelligently about. I am very happy that I stumbled across this in my search for something concerning this.”

The questions – there were many on pests and disease for example, how to eradicate them and by what methods, the protection of forests and woodland, tighter restrictions on importation, new phytosanitary regulations and will there be any detriment to bonsai horticulture.

1. Eradicating pests and disease – “What methods of eradicating pests and disease are currently in use and what is the success rate?”

For aeons agriculturists and horticulturists around the globe have been trying to halt the onslaught of pest and diseases that have devastated crops, forests and woodland. Many of these unwanted entities have arrived either by wind (pathogens) and wing (Insects) and through packaging in more recent times.

To date over 1 million species of insects have been discovered and described, but it is estimated that approximately 10 million exist on earth. There are 60,065 species of trees on the planet that we know of and more are being discovered. For each tree species there are over 100 pathogens, (60,065 X 100) plus.

Many we know of and are able to eradicate via insecticide and fungicide, but many chemicals are no longer effective and/or are not available for general public use for obvious reasons. Pesticides widely used include Cypermethrin, Glyphosate, Lambda Cyhalothrin, Chlorpyriphos, Cypermethrin Acetamiprid and Profenos Cypermethrin.

However, insects can become immune for example, the cotton bollworm Helicoverpa armigera has documented resistance to 49 pesticides. Pathogens are able to mutate and many are not affected by fungicide sprays and in some cases there is no chemical cure. Hence the success rate is minimal to say the least. Science has to find solutions that are safe not just for humans but also the environment.

2. Woodland and forest protection – “What methods or practises are in place to protect forests and woodland?”

Practically all foresters are knowledgeable regarding the health and status of their plants and are able to detect problems quite quickly when symptoms appear. However, there are diseases that attack tree root and water conducting systems for which the signs are not visible until it is too late for example.

Armillaria and Xylella fastidiosa, Anthracnose and Fire blight are visible as they attack foliage and small branches. Infected trees die within a short space of time, hence they are normally removed and burnt to avoid further contamination.

The World Trade Organization (WTO formed on January 1st 1995 with 164 members) is an intergovernmental organization that regulates and facilitates international trade between nations. Governments use the organization to establish, revise and enforce the rules that govern international trade.

However, there are 14 countries who are not members including, Aruba, Eritrea, Kiribati, Kosovo, Marshall Islands, Micronesia, Monaco, Nauru, North Korea, Palau, the Palestinian Territories, San Marino, Sint Maarten and Tuvalu.

Therefore, it is extremely difficult to enforce rules and regulations further if there is stiff opposition, because trade rules for agriculture remain an extremely sensitive issue. This is particularly the case when agricultural imports carry the threat of disease. Nonetheless, under the rules of the WTO member countries are allowed to restrict the importation of agricultural products from diseased regions should potential risks be apparent.

4. New phytosanitary regulations – “What do these new rules entail and can they be enforced?”

Every country on the planet is a sovereign nation and has the supreme right to make or change laws as it so desires, regardless of what treaties or agreements are in place. However, the nations in the EU block have to abide by the rules laid down by the commission, but the UK has parted company with the block and has no obligation to adhere to any mandate.

The latter passed new phytosanitary regulations in January 2021 due to diseases that are now rife in Europe, any country wishing to trade with the UK has to abide these new measures. Such mandates are regulatory in other nations including Australia, North America, Canada and Russia.

5. A detriment to bonsai horticulture – “Will these new restrictions have an effect on the bonsai fraternity?”

We are researching and monitoring new laws and what we can divulge is the from the 1st January 2022 according to the UK’s Department for Environment Food and Rural Affairs

“All plants, plant products and other objects categorised as either ‘regulated and notifiable’ or ‘regulated’ must be accompanied by a Phytosanitary Certificate – All plants, plant products and other objects categorised as ‘regulated’ will require pre-notification, but only if instructed to do so upon submitting a customs import declaration.”

Since leaving the EU, importing goods from the UK has and is an arduous affair with more paperwork and additional import duty costs and these new regulations now in situ just exacerbate the issue. Meaning purchasing bonsai products from the UK will not be impossible, but extremely tedious and time consuming.

No doubt the EU will probably reciprocate due to their petty minded bureaucracy because of the UK’s actions. However, there are many bonsai outlets on mainland Europe and other countries where the restrictions although in force are less rigid. Until next time, BW, Nik.