The Nation (Nairobi)

23 March 2006

Kenya: Eucalyptus Pest Spreads to Rift Valley

Nairobi — Farmers in western Kenya will have to stop growing eucalyptus, arguably the most popular commercial tree, at least for the time being according to the Kenya Forestry Research Institute.

An exotic eucalyptus pest-Blue Gum Chalcid-initially found in Western Province and later Nyanza has now moved to Kericho in the Rift Valley Province having stunted most of the trees on its path.

Now, says Mr Paul Baraza, the information officer at Kefri, farmers in the affected areas will have to cut and destroy all the infested materials.

Tissue cultured eucalyptus, he says are the most affected. "These farmers should avoid monoculture and incorporate other species especially indigenous ones at least for the time being."

Commercial outfit

Although the pest was first noted five years ago, it was not until last year the issue was highlighted in the media attracting a strong reaction from the Forest Department, Kefri and Tree Biotechnology Project. Tree Biotechnology Project is a semi commercial outfit within the Forest Department, trading among others in clonal and hybrid tree seedlings from South Africa.

Then, they had described media reports as alarmist, however Kefri and Forest Department now agrees the matter is serious and requires immediate intervention.

The spreading of the pest to Kericho in the Rift Valley has foresters worried. "This is unexpected, because initially we thought the pest's attack was severe in dryer areas," says Mr Joseph Nzwili, the Western Provincial Forestry Officer.

"It is a major threat for the fastest growing commercial tree, and we are trying all means possible to contain it," says Mr David Mbugua, the Chief Conservator of forests.

"We believe that farmers in Western Province must have grown wrong species, with seedlings from uncertified sources. They have to buy the seedlings from recognized institutions like Tree Biotechnology Project," he advised.

According to Mr Nzwili, the attack evident in Nyanza, Western and now Rift Valley provinces has affected between 20 and 40 per cent of all eucalyptus trees under five years old.

Destroy affected trees

Eucalyptus trees planted in the last three or four years ago are completely stunted at a height of about five feet due to the effects of the pest.

Mr Nzwili is in agreement with Kefri's earlier advice, that severely attacked trees must be cut down and burnt to avoid further spread of the pest. The advice is however not welcome by most farmers in Western Kenya, who feel they have invested a lot in the activity, and are not ready to count their losses.

"We need some kind of a legislature to force the farmers cut down the affected trees, to avoid further spread of the Chalcid," said Baraza. "This is a disaster, and all farmers need to understand it as such," says Mr Baraza. "Eucalyptus form up to 80 per cent of ground cover in western Kenya. And now the gap created by the pest is a serious problem not only for the farmers, but also the country's climatic patterns."

However, the commercially inclined Tree Biotechnology Project is not yet won over. This is not a big issue. The main reason for further spread of the pest in Western Province was the prolonged drought. There is no reason for farmers to panic, said Mr Benson Kanyi, the project director.

"This attitude does not go well with Kefri, the national forestry scientific arm of the government. Partner organisations have the responsibility to respect scientifically based decisions and join us in getting a solution. The farmers have the right to know what is happening, whether good or bad, at least for the bigger national benefit," said Baraza.

A spot check by Horizon in Western Kenya last week, along the Busia - Kisumu road, then Ebusakaami-Vihiga road, and a visit to over 100 homes in East Bunyore location of Vihiga District revealed almost 100 per cent of all eucalyptus tree species under three years old were under a severe attack.

Now, Kefri warns that if the infested trees are not destroyed and burnt, while bigger ones can be harvested, then the pest is likely to spread throughout the country.

The Blue Gum Chalcid, scientifically known as Leptocybe Invasa was first recorded in Kenya in 2002, and according to Eston Mutitu, a senior research officer at Kefri, it attacks nearly all the eucalyptus species, and stunts them completely.

The pest is said to hide on the underside of the leaf and mounts a complex defensive mechanism against any attack, making control very difficult.

It rapidly induces gall formation on the leaves, which later attracts nutrients denying them to the shooting tips of the host tree, leading to stunting of the young foliage. The adult insect, which is said to be 1.5mm in length lays up to 300 eggs immediately after emergence from the host plant. The adults can fly and spread very fast aided by wind.

"The pest has had an adverse effect on the most common eucalyptus species grown in Kenya namely, grandis, camaldulensis and saligna, as well as most clonal species imported into the country," said Mr Mutitu.

For several years, eucalyptus trees have been pest free all over the world, until the year 2000 when the Blue Gum Chalcid was discovered for the first time in history. "We are afraid because up to now, we have not found a proper means of controlling or combating the pest," said the senior research officer.

Apart from Kenya, the first attacks were observed in Morocco, Iran, Uganda, Ethiopia, Italy and Israel. However, Kefri among other organisations worldwide are engaged searching for ways to control the pest.

Kefri has recommended the use of pesticides-Menthox 90SP and Confidor- for spraying against the Chilcid "Though the pest has ways of evading the chemicals by hiding under the epithelial cells of the leaf," said Mr Mutitu.

But according to Nzwili, the chemicals are not the best option, because they are expensive, difficult to apply and are a serious threat to the environment.

Observations by farmers in affected areas show that trees grown in extremely fertile areas and wetlands are better off. "Trees planted in swampy areas are doing better than the rest despite the attacks," said Japheth Teka, a small scale farmer in Emuhaya.

But foresters are opposed to the planting of this tree in wetlands. "These trees are meant for dry lands because they are known to drain the soil moisture. In fact, they are supposed to be drought tolerant," said Mr Baraza.

The pest has many villagers worried. "We are afraid that at this rate of infestation, our farmers will encounter serious loses," said Mathews Olasia, assistant chief, Esianda Sub-location in Western Province.

"We have, through the forest officers tried to advice farmers to cut down the stunted trees but with little success. For years these people have depended on the tree for firewood, construction and a host of other uses and can't imagine a life without eucalyptus," said Mr Olasia.

The spread of the pest to the Rift Valley could be a major disaster because of huge investments made on eucalyptus and its central role in the curing of tea in the area.

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