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New Pest Threatens To Wipe Out Eucalyptus Trees

By Vision Reporter

Added 8th March 2004 03:00 AM

UGANDAN Eucalyptus trees have an uninvited guest.
The visitor, an exotic insect pest is believed to have come from Australia is known as the blue gum chalcid. The pest is attacking eucalyptus (kalitunsi) trees, severely affecting their growth.
As the pest matches across the country from ea

UGANDAN Eucalyptus trees have an uninvited guest.
The visitor, an exotic insect pest is believed to have come from Australia is known as the blue gum chalcid. The pest is attacking eucalyptus (kalitunsi) trees, severely affecting their growth.
As the pest matches across the country from ea

By Gerald Tenywa

UGANDAN Eucalyptus trees have an uninvited guest.
The visitor, an exotic insect pest is believed to have come from Australia is known as the blue gum chalcid. The pest is attacking eucalyptus (kalitunsi) trees, severely affecting their growth.
As the pest matches across the country from eastern Uganda, tree farmers who have invested heavily in the fast growing trees are facing a disaster.
“The pest has been reported all over the country damaging mainly nursery seedlings and young trees, but also older trees,” says Peter Kiwuso of the Forestry Resources Research Institute (FORRI) under NARO.
Kiwuso says eucalyptus, which takes four years to mature, had become an attractive tree and its destruction would cause shortage of timber, poles and firewood.
The pest, which is behind the crumbling of the “great green wall” of eucalyptus trees mostly sheltering peri-urban areas, belongs to a group of wasps, says Kiwuso.
Kiwuso says the adult pest, though tiny, is visible to the naked eye and is black in colour with transparent wings.
Kiwuso says the pest becomes destructive during its reproduction process. “They lay eggs in the tender parts of the plant, which react by forming galls (swellings),’’ he says.
The attacked leaves fold and remain tiny leading to stunting of the whole plant, Kiwuso says.
Kiwuso says the worst hit districts were Mpigi, Luweero, Masaka, Kasese, Mbarara, Bushenyi, Mbale, Kapchwora, Tororo, Lira and Apac.
The pest, which is new in the history of eucalyptus in Uganda, has also been reported in Kenya and other countries of the Great Lakes region, he says.
Eucalyptus, originating from Australia, has been planted in Uganda for about a century now. About 60 species have been introduced and they can thrive in all parts of the country for pole and fuel wood production. But some are also converted into timber.
Later, a peri-urban plantation programme was initiated in Kampala and Entebbe with the aim of increasing wood fuel and poles for use in the urban areas. But the eucalyptus has now become a popular commercial tree, which is spreading in the countryside like wild bush fire.
Kiwuso and their Kenyan counterparts have been trading accusations. While the Kenyan researchers say the pest spread to their area from Uganda, Kiwuso insists that the initial reports about the pest came from Busia, a border district, with Kenya.
Eucalyptus is prone to termite attack, which farmers have been battling sometimes by planting the Neem tree, which is widely believed to be an insect repellant.
Other farmers apply chemicals to exterminate the termites when they attack especially in the dry season.
However, Kiwuso is critical about using pesticides saying they only offer a temporary solution and besides, the expense, can cause pollution and can be hazardous to non target organisms.
“Our recommendation is that this pest should be managed through biological control method,” Kiwuso says.
“This being an exotic pest, biological control (in which a natural enemy is used to regulate insect pest populations) may offer an environmentally sound alternative,” he says.
Kiwuso says a survey was underway to find out the extent of infestation, damage levels, population dynamics of the pest and local natural enemies to the pest.
Researchers in Uganda are treading on a familiar ground regarding the use of biological control and are positive because they controlled the cypress aphid, pinewoolly aphids which were ravaging the trees in the plantations.
One of the recommendations to control further spread of the pest is to restrict movement of seedlings or planting material, Kiwuso says.
Another is to cut down and burn heavily-infested plant materials, he adds.
He also advises farmers to plant seedlings, which are free of the pest.
Over 90% of Uganda’s national energy demands are met by wood fuel, according to a report from the Ministry of Water, Lands and Environment compiled three years ago.
Kiwuso says that the destruction of the eucalyptus by this pest will increase pressure on the already dwindling natural forests.
Kiswuso says that a work plan has already been prepared to initiate activities against this pest.

New Pest Threatens To Wipe Out Eucalyptus Trees

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