Peter Maina
18 November 2004
Nairobi — The now popular hybrid Eucalyptus tree faces destruction by an insect that invaded the country from Uganda. Scientists estimate that about 40 per cent of Kenya's forests could be destroyed. Eucalyptus trees form the single biggest family of plantation species in Kenya's forestry.
Scientists liken the threat to the 1990 massive destruction of cypress trees by an alien pest in Kenya. The blue gum chalcid is an insect in the bee-wasp family and like the eucalyptus, it is a native of Australia.
It has extensively damaged the Eucalyptus in Iran, Israel, Morocco, Italy and Uganda. In Kenya, it entered from the western direction where it is doing great damage.
According to Eston Mutitu, a senior researcher at the Kenya Forestry Research Institute (KEFRI), the country is yet to come up with a solution to counter the destructive insect. However trials are underway to introduce a biological control.
Addressing a scientific conference at Kefri earlier this month, Mutitu said the most affected are the now popular tissue culture species compared to traditional ones that have been in the country since the early colonial days.
The chalcid kills the tree by feeding on the leaves, especially in its larval and adult stages. This makes the tree to fold into an umbrella shape and start collapsing as the affected leaves turn into "ash" before falling.
There are over 800 species of Eucalyptus worldwide, with Kenya hosting some 600 of these. Enumerating the virtues of the tree, Paul Barasa, the information officer at KEFRI, says that Eucalyptus is even referred to as the woman's tree because of its popularity among women in rural Kenya. Barasa adds that although the species is allegedly said to be water wasting, it will end up consuming less water in its fast growth of 10 years, than an indigenous tree like camphor in its long life of 30 years.
As a matter of fact, Barasa says that Eucalyptus can be used by a farmer to drain off unwanted water logged patches of the farm. Where scientific evaluations are done in an exercise called species- site matching, the tree can be used to support local biodiversity. The sunbirds and many insects for example, find Eucalyptus forests a very conducive home due to plenty of food in form of flower nectar.
The tea and tobacco industries find it ten times cheaper to cure their leaves using Eucalyptus firewood in their furnaces compared to fuel oil. Not surprisingly, the different tea farms in the country and the Tea Research Foundation have the biggest acreages of Eucalyptus forests, even surpassing those of the Forest Department (FD).
Eucalyptus is also widely used in the pharmaceutical industry especially in making nose-unblocking sticks and skin rubbing ointments. Sweets, toothpastes and confectionaries are also blended with Eucalyptus oil for flavour. Honey made by bees feeding on Eucalyptus flowers is also recognised as one of the best in the world. As a result, Australia is a leading honey producer.
Thirty per cent of paper made in Kenya comes from Eucalyptus pulpwood. The other 70 per cent is from pine which was introduced by the colonial government from New Zealand.
If properly pruned, Eucalyptus grows in a straight posture (stand) making very good poles. The local telephone and electricity companies (Telkom and KPLC respectively) find the tree very useful in the extension of their landlines.
Where the tree is needed for firewood, it is not pruned but is instead allowed to grow in multiple-bushy branches. The tree can yield big wood volumes in a relatively short time of about five years.
The new threat comes a few years after another pest destroyed huge plantations and hedges of cypress plantations. The European aphid that had attacked the country came through the Tanzanian border in 1990. Today it has been effectively countered by introducing a biological agent called The Little French wasp (Pauesia juniperorum), which feeds on the destructive pest.
For the blue gum chalcid, the scientists at KEFRI say, it may take time to contain since they are yet to identify its natural enemy. They say that although the local spider feeds on the chalcid, it is not effective enough. Barasa says that any biological agent imported to fight the chalcid will first need to undergo strict quarantine conditions to ensure that it does not have negative secondary effects on other local plants and animals.
The problem of tree pests in the country is bound to affect the forestry sector more in future as new organisms imported through germplasm (plant material) attack local plants. This will need a lot of surveillance both in terms of manpower and many geographic monitoring sites.
Be the first to Write a Comment!
Copyright © 2004 The Nation. All rights reserved. Distributed by AllAfrica Global Media (allAfrica.com). To contact the copyright holder directly for corrections — or for permission to republish or make other authorized use of this material, click here.
AllAfrica aggregates and indexes content from over 125 African news organizations, plus more than 200 other sources, who are responsible for their own reporting and views. Articles and commentaries that identify allAfrica.com as the publisher are produced or commissioned by AllAfrica.
