The term “sooty” means black or dark brown in English. Sooty fungus is a type of fungi that grows on trees and other plants. It causes the appearance of burned bark, which resembles burnt wood.
Sooty fungus is found in forests around the world including North America, Europe, Asia and Australia. Some species are known as white rot fungi because they cause white rotting wood (white rot).
White rot fungi are not harmful to humans. However, it may affect trees and other plant life if they grow near the infected areas.
Sooty fungus can be identified by its spores, which look like tiny black specks. These spore particles are called mycelium and they produce fruiting bodies (mycelia) when disturbed or killed by fire or insect attack.
When the spores fall from the air onto soil, they become mycelial growths. When these mycelia (fruiting bodies) grow into branches, trunk or leaves, they can form a fungus infestation.
The fungus grows under the surface of the ground where it can survive all weather conditions.
It takes three years for a single mature mushroom to develop into a full-grown fungus. A new infection will start after another two years have passed since initial infection.
This is when the fungus starts to release its sooty spore.
The fungus can survive any climate or weather condition. It can be spread by birds, animals, humans and any other living organism that comes into contact with it.
When an infected tree is cut down or a dead tree falls to the ground, it spreads the fungus more quickly. The ground will be especially at risk if it receives a lot of rainfall, which helps the fungus spread even further.
The sooty fungus can cause the tree’s trunk to become black, hard and brittle. This can lead to the death of the tree within weeks or even days from the moment it became infected.
During high risk times (summer, dry seasons) a single rainstorm is all that is needed to spread the infection further into areas that are susceptible to fungal growth.
White rot fungus look like dark patches on tree bark. These patches have a “burnt” appearance and are easy to spot.
The infected bark will appear rough, cracked and dark brown in color. It may also be lighter or darker than the surrounding areas. The patterns of the infected bark can vary from circular patches to irregular blotches and stripes.
The fungus spreads through the tree’s system of vessels or tubes that transport water and nutrients throughout its body. The nutrients are transported from the soil, up through the roots, into the trunk and out to the branches and leaves.
When a tree becomes infected, it starves and weakens until it eventually dies. The fungus continues to spread throughout its body even after the host tree has died.
The life cycle of sooty fungus is complex. It can be broken down into four distinct stages:
1. The mycelium or vegetative stage
2. The fruiting body or reproductive stage
3. The spore dispersal stage
4. The infection stage
The mycelium or vegetative stage of life begins when the spores land on a tree’s bark and germinate. A fine network of filaments called hyphae emerge from the spore.
These hyphae permeate the tree’s bark, searching for nutrients such as cellulose.
The mycelium can spread throughout the tree, digesting a large amount of nutrients from it. It can also grow through a single branch.
When there is no more nutrition left in one area, the mycelia will move on, in search of food.
Once the mycelia has completely penetrated and digested the host tree, it will begin to produce fruiting bodies. A fruiting body is different from the mycelia in the sense that it produces spores.
These spores will be released into the air, carried by the wind to nearby trees.
The mycelia is asexual; it does not need another mycelia (or any other organism) to reproduce. It can do so all by itself and will continue to do so until there is no more food (trees) left to infect.
The mycelia that spreads through one tree can also spread through several others. The rate of growth through a single tree is around 3.8 centimeters per day.
Fruiting bodies grow on average 1.3 centimeters in one day.
The life cycle starts all over again when the wind picks up the spores and spreads them to other trees.
The mycelia of the sooty fungus can be found throughout the world, although it grows best in warm, wet and humid climates. It is more common in tropical or subtropical areas.
Sooty fungus is not harmful to humans who wish to eat the fruit (or other parts) of an infected tree, but it can be fatal to the tree itself.
Sooty fungus has been used as a biological pesticide to protect trees against insects and pests that damage or destroy them. It is also used in the lumber industry.
The fungus persists in the tree after it has been cut down and can be used to protect it from fungal or bacterial attack during transport.
Sooty fungus can also be used in a wide range of medical treatments.
The mycelia can be used to strengthen the immune system. It is also being tested as a possible treatment for cancer.
The fruiting bodies of the sooty fungus contain peptides that can fight certain viruses. These peptides can also kill cancer cells, boost the immune system and fight certain bacterial infections.
Sooty fungus can be used to make a range of dyes.
The sooty fungus is not generally eaten by humans except in times of famine. It is possible that it might be cultivated as a food source in the future, although there are no immediate plans to do so.
Sources & references used in this article:
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Dieback and sooty canker of Ficus trees in Egypt and its control by MEAA Rehab, MF Rashed, MI Ammar… – Pakistan Journal of …, 2014 – researchgate.net
First report of multiple species of the Botryosphaeriaceae causing bot canker disease of Indian laurel-leaf fig in California by JS Mayorquin, A Eskalen, AJ Downer… – … Disease, 2012 – Am Phytopath Society
First detection of Neoscytalidium dimidiatum associated with canker disease in Egyptian Ficus trees by OA Al‐Bedak, RA Mohamed, NH Seddek – Forest Pathology, 2018 – Wiley Online Library
Sooty canker of mulberry (Morus alba L.) in Arizona by HA Dill – 1953 – repository.arizona.edu
Effect of heat-stress predisposition on the development of sooty canker caused by Neoscytalidium dimidiatum (Penz.) Crous and Slippers by WA Hassan, RA Haleem, PH Hassan – Acta Agrobotanica, 2011 – agro.icm.edu.pl
Sirococcus Clavigignenti-Juglandacearum: An Undescribed Species Causing Canker on Butternut by VMG Nair, CJ Kostichka, JE Kuntz – Mycologia, 1979 – Taylor & Francis