Healing Trees for Ailing Man – Eucalyptus

No one in the tribe cared for Kooboo the orphan. No one gave him food or even water when he was thirsting. And so Kooboo was always hungry and thirsty, for it was a hot dry land and people had to fetch water from far away. They stored it in pots made of tree trunks. And when they went hunting, they hid the pots.

One day poor Kooboo came upon a hollow gum tree. He was delighted to find the hidden water pots. Kooboo drank his fill; then Kooboo grew mischievous. He plunged into the water and splashed and played.

One by one he hung all the water pots on the branches of the gum tree. Then he sang a magical song. The tree understood and grew and grew till the branches with the water pots were high up in the air.

The people came home and looked for their water pots. They looked low and high. At last someone saw them hanging on the highest branches. They tried to climb up but Kooboo threw dry branches and laughed at them; for had not these people been cruel to him.

Then one man decided to climb the tree in a spiral. However many Kooboo branches threw, he could not hit him. He reached the boy and pushed him hard.

Kooboo fell to the ground but the magic turned him into a small furry bear-like animal. It scampered up the gum tree and since then no one saw Kooboo again. But people saw a furry little animal eating the leaves of the gum tree and never needing water.

That was how the koala came to the Australian land.

-Australian folktale

The locals call eucalyptus ‘gum tree’ for when the bark is cut, it exudes a gum or sap. Eucalyptus leaves are food for cute koalas and other possums, even though it can be poisonous to most animals.

White gum, blue gum, scribbly gum and stringybark – 75% of Australian trees are eucalyptus. There are over 600 species ranging from large trees to mountain shrubs. The tallest is the Mountain Ash (E. regnans) which can grow to over 100 metres. The eucalyptus is also one of the fastest growing trees.

The arid regions of Australia often have forest fires and the eucalyptus has learnt to live with it. In fact eucalyptus seeds can germinate only after they are roasted.

The trees burn like huge fire-crackers, sometimes exploding like a bomb; for the eucalyptus is literally a fuel-tank, storing rich gums and oils in its bark and leaves.

Traditional Use

The eucalyptus is sacred to the aboriginals and appears in Dreamtime or Jukurppa stories.(Most of the knowledge is lost today as white settlers marginalized the local communities and much sacred knowledge died with the medicine men.)

When thirsty, Aborigine people chewed the tree roots for water. For rheumatics, steam pits were made lined with eucalyptus leaves over which they sat. They were also used to heal open sores and wounds and fungal infections. And infusions of eucalyptus leaves treated fevers. They were also smoked as cigarettes for coughs and respiratory problems – a process later learnt by the early white settlers.

In the 18th century Mary Gilmore reported in her journal how the immigrants had learnt much from Bush medicine including ‘eucalyptus beds and steam pits for cold and rheumatism’. And that the eucalyptus extract industry had come about by following local knowledge.

The Aborigines and later the immigrants used the eucalyptus to make plant dyes. Different eucalypts and plant parts gave different dyes. The Didgeridoo or the Aborigine drum was made of eucalyptus branches hollowed out by termites!

Science Says

Its medicinal use and the belief that eucalyptus plantations discouraged malaria made it a popular tree in the late nineteenth and early twentieth centuries. Eucalyptus began to be grown in many areas of the world and its properties studied.

Eucalyptus contains phenolic compounds. The tannins in eucalyptus help to reduce inflammation, the falvonoid querctin is an anti-oxidant. It also contains terpenes which are useful as industrial oils – for separation of metals from ores. It is valued in the paper and plywood industries too and as a fuel.

The oil contains 80% cineole or eucalyptol giving it antiseptic properties. When exposed to the air, eucalyptol turns into a crystalline resin: it can check bad breath and so it is used in gargles.

Researchers at the University of Kiel, Germany found that a mix of the essential oils of peppermint and eucalyptus is helpful in headaches. They say that the decongesting effect is due to its action on the cold receptors.

Another study said apart from being an inhalant it helped to cure mild snoring!

Recent studies find that the leaves have some anti-diabetic, diuretic and anti-tumour action. Aqueous extracts increased insulin production and reduced blood sugar in tests on mice. However its safety and efficacy has yet to be established clinically.

Present Use

Eucalyptus oil is mentioned in the Commission E monographs, British Pharmacopoeia and the pharmacopoeias of China, India and others. It is used primarily as a cold medicine – in inhalers as a decongestant, in rubs and vapor baths for respiratory and bronchial diseases, in gargles for sore throats. Vicks Vaporub is one of the most well-known and global brands using eucalyptus oil. Another is Listerine and Mentholatum. Apart from this hundreds of balms and cold medicines all over the world use eucalyptus oil.

Eucalyptus oil is added to ointments for insect bites and insect repellant sprays. It is also blended with other oils in pain balms.

Like many useful plants they are now grown all over the world’s tropical and sub-tropical belt and even in temperate regions. But the eucalyptus can suck up water from great depths and drain the soil. Being water guzzlers, they do dry out the land, sometimes drying it so much that other trees cannot grow!

But when you have a cold or are plagued by mosquitoes, relief is at hand in the eucalyptus oil bottle.

This is the second part of a series on Healing trees. I wrote about some key trees of the world – trees important in their native regions and the world. I am keen to publish it as I feel it provides a holistic view of the Man-Nature relation.

Oak Leaf Anthracnose

Many trees, both native and ornamental can be affected by anthracnose disease. These fungal diseases cause premature browning, shriveling, and leaf drop. For some trees, such as Modesto Ash, Sycamore, and Chinese Elm, this can be an almost annual event often causing complete defoliation. For other species of trees, including native oaks, the effects are dependent on spring weather and / or, the local micro-climate. Often these symptoms subside or disappear as summer approaches with warmer, dryer conditions.

Weather Conditions: For many species of trees, wet cool springtime conditions have the greatest influence on the severity of infection. In Sonoma County and the San Francisco Bay area in general, late rain from April through June and or dense morning fog during the same period promotes the development of the fungi that cause anthracnose. Even the micro-climate within a neighborhood or property may affect which trees become infected with some trees exhibiting minor or no leaf damage while others become defoliated.

Symptoms: For oaks, the leaf damage caused by anthracnose infections vary from small brown spots on the leaves, to large brown spots, to curled and deformed brown or dead. Severe infections can cause current season twig growth to become infected and die back as well. The most obvious sign of this disease for most people is early leaf drop which sometimes continues through the summer. Complete defoliation is uncommon in my experience but 50%-75% does occur. Because anthracnose is not a problem every year, our native oaks seem to tolerate the disease very well. While mostly a benign disease, many property owners become justifiably concerned when their oaks begin dropping leaves prematurely.

Affected Trees: In the Bay Area of Northern California all our native oaks are susceptible to this disease. Black oak in particular seems to be most affected by anthracnose in part, I believe, because it is the first oak to break bud in the spring, making it more susceptible to disease infection. Valley oak and blue oak are also susceptible if cool damp conditions persist through the spring. Coast live oak may also be affected but their leathery leaves seem less affected than the other species. Trees affected by anthracnose early in the season may produce a second flush of leaves in the summer provided the climatic conditions that foster the disease have passed.

Treatment:

Native California oaks, in general, don’t need any type of treatment to control anthracnose infections because of the infrequency of infection. Generally the disease is cyclic with several years between severe outbreaks which may cause some individuals to be almost completely defoliated. Sanitation is the best treatment for native oaks which focuses on the removal of infected plant parts such as leaves and twigs. Pruning can also help if done properly by removing only small twigs and dead branches. Severe pruning can be detrimental to oaks and can promote other diseases such as powdery mildew by promoting uncontrolled sprouting. Overhead irrigation systems used on other plants or lawns but near oaks can increase the frequency of anthracnose as well.

Sherby Sanborn is a Consulting Arborist in Sonoma Valley, California.

My professional career began as an economic entomologist and then a forester working on the Department of Forestry and Fire Protections (CDF, Cal Fire) Dutch Elm Disease (DED) project.