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How does your garden grow?  By Eric Danell


How to communicate danger in a pedagogic way

As a university lecturer in mycology I have also had the pleasure of teaching very young children about mushrooms. I soon realized that some children did not seem affected by the explanation that a number of mushrooms are deadly poisonous. Death might be an abstract phenomenon to a young child, so I had to adapt my pedagogic approach to the experience of my audience: I explained that if you eat the wrong mushroom, you will suffer from severe diarrhoea and poo everywhere like a little baby.

That description was enthusiastically accepted by the audience who knew both poo and babies.

Dendrobium spatella is an indigenous Thai orchid which we grow at Dokmai Garden. (Photo by Eric Danell)

So, how do we communicate to adults that it is a shame we are currently destroying the original forests and their creatures, that lost species will be gone forever, and that new species may need tens of millions of years to evolve?
Perhaps we need to change the time scale from the abstract ‘ten million years’ to ‘how will our descendants, left in a junk yard, judge us 80 years from now? Then the issue becomes a question of shame and honour.

When I was a child I was warned by my father that a particular knife was very sharp, and a second later I tried the edge and cut my finger. My father could not believe his eyes when he saw my ‘stupidity’, and I agree it was stupid, but on the other hand it is a scientific approach to test a statement yourself. Many mistakes made by the western countries in 1860-1960 are now repeated by developing countries, in spite of recommendations. The problem with biodiversity decline is that a band aid will not help if a species is lost.

The first pedagogic challenge is to explain why we need 1100 wild orchid species in Thailand, when the shopping malls seem to function fine without them. We should not use hollow arguments such as ‘all species are equally important, and society may collapse if we lose one’. Most people can see that statement is more religious than empirical, and then people may lose interest in your faith. Better tell the truth: the world becomes poorer, uglier and less interesting! Replacing an avatar-like forest with rubber trees and corn is like burning down a national museum to build a chicken farm. This demands some knowledge in the mind of the discussion partner, which is why education is extremely important. However, today’s military regimes in surrounding countries are not educated and since the forests will be gone in our time the argument of disgusting behaviour will be in vain.

A more clever argument is money. Save the forests to make money on tourists. Again, it is a matter of education, as most Thais never travel abroad, and therefore they have only a vague imagination about what eco tourism and safari is. Proper scientific studies of eco tourism in Australia with actual dollar signs, in combination with study trips, may do the trick.

I also believe that carbon dioxide as an explanation for the global warming is wrong, and that this mantra blinds us from real disasters such as the current extinction of species. Again, education and open discussions between different scholars (not politicians, not environmentalists, not journalists) would help people judge for themselves.

If any of our readers have more suggestions on pedagogic approaches to communicate the importance of supporting conservation efforts, please let us know on the blog ‘The Last Days of the Orchids’. [email protected]

Is it dangerous to walk barefoot in the garden?

By Eric Danell, Dokmai Garden

Thai: Put on your shoes, or you will get worms!

Farang: What are you talking about??

Diospyros mollis, a native ebony used to treat worms. If you visit Dokmai Garden you can see the actual tree. Ketsanee’s grandfather used these fruits regularly to keep his stomach trimmed.

A foreigner coming to the tropics may not be aware of the tropical parasites. The background to this conversation is that hookworms (nematodes in the genera Necator and Ancylostoma) may enter your skin and cause dermatitis. The worms are actually intestinal, and if present in your garden they probably originate from dog or cat poo. The dangerous hookworms are those specialised on man, and they spread via human poo and infect new victims via the skin of your feet. The hookworms suck blood causing anemia and may cause severe damage to pregnant women and their babies. The disease is often symptomless but serious. The worms can migrate everywhere in the body, and even transfer to newborn babies via the mother’s milk, and kill the babies. About 10% of the world’s human population is infected.

The worms thrive in moist sandy soils, but will die during droughts and sunshine.

How do you protect yourself? To avoid the skin rash caused by hookworms from dogs and cats, give your pets vermicides, and put up a fence so that alien pets cannot invade your garden. Always wash vegetables from another place than your own garden. To avoid human hookworms, avoid walking barefoot outside your garden. If you know that nobody can use your garden as a toilet, enjoy the grass between your toes!

Since many worm infections occur in the tropics (pinworms, Ascaris affecting 25% of the world’s population, tapeworm and fasciola) many Thais regularly eat commercial vermicides. Before chemical treatments, the Thais would use the fruits of Diospyros mollis (Ebenaceae) or the leaves of Azadirachta indica (Meliaceae). The best vermicide was opium, made from the poppy Papaver somniferum. [email protected]

On slugs and snails

Slugs (no shell) and snails (have shells) may become pests in a Chiang Mai garden. The Tropical Leatherleaf (Laevicaulis alte sensu lato, tak nang) is a flat, brown slug which often hides its tentacles. It is well adapted to the dry lowlands, hiding underground at daytime, and feeding on your plants at night.

The invasive Golden Apple Snail (Pomacea canaliculata, hoi cherry) is an underwater snail that can grow as large as an apple.

Another Chiang Mai gastropod is the East African Landsnail (Achatina fulica, hoi tak african). It can grow big as a hand, and has a conical and quite ornamental striped shell. These snails eat plants and even concrete to get calcium for their shells. The snail was reported from China in 1931, where it was introduced as food.

A third invasive gastropod is the Golden Apple Snail (Pomacea canaliculata, hoi cherry). It is an underwater snail, with yellowish round shells that can grow big as an apple. Its spectacular pink eggs are laid above the water level. This snail was introduced from South America to clean fish tanks, and was promoted as a food for people. It was found in the wild in Thailand in 1984, and is now the most serious pest in rice and taro fields. This has resulted in an increased use of pesticides. This seems unnecessary, as many wild fish, birds, mammals and crabs eat the snails. Since such predators are almost extinct due to cats, dogs and hunting, the snails propagate out of control. Also in natural wetlands, this snail eradicates the native flora, and outcompetes its Thai cousin Pila polita (hoi kong), which has white eggs and darker shells.

All of these gastropods may be vectors of the rat lungworm (Angiostrongylus cantonensis, pajat toa gom), a nematode that resides in lung arteries of rats, and may infect humans, causing fatal encephalitis as a result of undercooked snails or unwashed vegetables. Slugs and snails can be controlled by fowl, herons and frogs. Nocturnal snail hunters such as fireflies, which are most spectacular beetles in any garden, benefit from a heap of branches to promote breeding. Gardeners can make a difference by creating a refuge for Thai wildlife! [email protected]