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New pest attacks eucalyptus

By Vision Reporter

Added 20th December 2004 03:00 AM

EUCALYPTUS tree farmers should brace themselves for harder times. While eucalyptus is becoming an important commercial tree, new reports indicate a pest, which invaded the country about two years ago, could ruin the dreams of the farmers.

EUCALYPTUS tree farmers should brace themselves for harder times. While eucalyptus is becoming an important commercial tree, new reports indicate a pest, which invaded the country about two years ago, could ruin the dreams of the farmers.

By Gerald Tenywa

EUCALYPTUS tree farmers should brace themselves for harder times. While eucalyptus is becoming an important commercial tree, new reports indicate a pest, which invaded the country about two years ago, could ruin the dreams of the farmers.

A report released after a countrywide survey indicates the pest could destroy more than 30 per cent of the eucalyptus plantations.

As the pest traverses the country, panicky farmers say “the gods have gone crazy.’’

Unknown to most of them is the fact that an insect, the blue gum chalcid, is behind the destruction.

The insect feeds on parts of the leaves causing folding of the young leaves and subsequent stunted growth, according to Peter Kiwuso of the Forestry Resources Research Institute (FORRI).

This has become a problem to foresters who hoped to encourage planting of fast-growing trees to avert wood crisis.

“The death of eucalyptus plantations will leave a big gap in the wood products and this could substantially increase pressure on the already dwindling natural forests,’’ the report says.

About 97 per cent of Ugandans rely on firewood for fuel, according to a recent report by the National Environment Management Authority (NEMA).

This demand for firewood and other wood products had resulted in high investment in eucalyptus plantations by both the Government and private investors.

One of the advantages of eucalyptus tree planting is reduced pressure on the dwindling natural forests of Uganda, according to Kiwuso.

“Unfortunately, eucalyptus is under serious attack from the pest,’’ he says.

Eucalyptus originated from Australia and was introduced in Uganda about a century ago, but remained unpopular until recently.

FORRI had introduced clonal eucalyptus which matures faster, giving timber within a decade as opposed to native trees that take more than two decades to mature, says Gaster Kiyingi of the National Forestry Authority (NFA).

The report says the new pest is an economic disaster.

In Masaka district, one of the country’s largest source of eucalyptus, the damage is already being felt, says Mohammed Sekyewa, a private tree planter.
However, the farmers have not given up on planting the tree despite the problem.

Sekyewa says concerned authorities at the district were not aware that the trees are under attack.

Uganda and Kenya are trading accusations over the origin of the pest.

Kiwuso says the pest was initially reported in the border district of Busia.

According to the pest incidence survey, more than three quarters of the country has been infested with the pest.

Other areas, which Kiwuso’s team visited included government and private plantations and nurseries in Mbarara, Ntungamo, Kabale, Masaka and Mpigi.

There were, however, no signs of the presence of the pest in Kabale, probably because of the cold weather, which does not favour reproduction of the pest, according to Kiwuso.

Kiwuso says they are looking for a biological control measure to the pest. He says the biological control method has already been successful against the Cypress and pinewolly aphids which previously destroyed conifer plantations.

During this study, a few local natural enemies were observed on the infested plants. The natural enemies included spiders, ladybird beetles and synphide.

Their role as natural enemies has to be observed further as they are known to be general feeders that may not concentrate on the pest to cause significant reductions, according to Kiwuso.

One of the recommendations is to remove and burn severely infested trees. Farmers should also avoid planting infected seedlings. The report also recommends drainage of severely water logged areas to reduce stress on the plants. “Stressed plants are more prone to attack than healthy ones,’’ he says.

However, pesticides such as dimethoate and salut could be used at the nursery for tree seedlings, but would be uneconomical at the farm. “They would also pollute the environment,’’ warns Kiwuso.

He also says pesticides would cause pest resurgences. This occurs when pesticides kill the predator and the population of the pest builds up thereafter because there is no biological enemy to check it, he says.

With the help of NFA, Kiwuso has set up sample plots to monitor the population and dynamics of the pest.

Kiwuso says FORRI is sharing information with other research institutions and the Centre for Agricultural Biosciences International on the possibilities of introducing a biological enemy.

He says they have produced pest watch brochures to create public awareness.

New pest attacks eucalyptus

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