By Gerald Tenywa

After investing billions in a tree planting enterprise, the least farmers would want to hear is an attack on their trees.

So when a moth was recently detected, crunching and munching away the leaves of pines and cypress in Kabale, south western Uganda, the news spread among tree investors.

Peter Kiwuso, a principal research officer with the National Forestry Research Resources Institute (NaFORRI) told New Vision that the moth, Gonometa Podocarpi, was threatening to knock down the great green wall forming Kiriima Forest, Kabale.

So far, about 10 hectares of soft wood plantation on Kiriima Forest has been affected and was now spreading to other parts of the forest.

The latest report, according to Kiwuso is that the pest is spreading to woodlot belonging to private farmers.

“This pest is causing serious damage because it eats all the leaves and retards growth of the trees,” Kiwuso said.

“Tree farmers are worried. We really have to do something,” he said.

In Uganda, like many developing countries, plantation is important to the country as the threat on natural forests is bigger.

Kiwuso says tree plantations need to supplement the natural forests so as to compensate for the expected shortage of wood.

He also pointed out that insect pests such as the moth are a major challenge in these exotic plantation species.

Following the outbreak in September 2011, the National Forestry Authority (NFA), which is the first casuality of the attack, organised an assessment in Kiriima.

According to Kiwuso, the damaging stage is the larvae.

He pointed out that the larvae were observed bending the needles (leaves) of the branches and eating them completely.

He disclosed that the pest is not new in Uganda, having been found on Mt. Elgon where it was feeding on indigenous conifers in 1965.

An outbreak in which 40 acres of forest were stripped of their leaves, was in 1965. Between August and September 1969, another 16 acres were completely destroyed, while another 16 acres suffered about 50-70% of destruction.

Causes of outbreak

For about four decades, this moth has not caused any havoc, what then is the cause of these resurgences in Kiriima?

Asked to explain the sudden outbreak of the pest, Kiwuso pointed out that it could be due to climate changes or environmental destruction, which could be affecting the population of the predators that prey on the troublesome pest.

“A lot of habitats are being converted into farmland and it could also be affecting the predators,” says Kiwuso.

“The causes of resurgence could be shortened life cycle of the pest, enhanced reproductive rate, higher feeding rate and destruction of natural enemies, all which can lead to disharmony with biological control agent lifecycle,” says Kiwuso.

“This is possible with changing climate and we have to investigate.”

Researchers identify natural enemy

However, the pest populations will most likely decline due to the action of the natural enemies.

According to Kiwuso, the natural enemy is a wasp, which was reared at NaFORRI.

“The contribution of the wasp has not been assessed,” Kiwuso stated in a report, compiled after the first visit to Kiriima.

A virus that was previously found killing this pest was successfully used against the pest at Muko in the 1970s.

“Unfortunately, we have not been able to isolate this virus during this study,” says Kiwuso, adding that further research on the virus would be intensified.

Reactions of tree growers

Allan Amumpe, the head of the Saw Log Grant Programme Scheme (SPGS) says the attack creates uncertainty for the tree planters.

“It is a big source of concern for people who have invested billions of money in tree planting,” says Amumpe. Amumpe added, “Kiwuso and his team are doing their best to find remedies, but what happens in the meantime. Do we stop planting?”

George Zentalo, a tree farmer, in Kanungu, says the problem of diseases and pests is a serious concern that should be addressed immediately by the Government.

“Tree growing is an expensive venture and the Government needs to come in with research and advise farmers appropriately,” says Zentalo.

Uganda runs out of timber

This comes at a time when Uganda has run out of mature plantations for timber production.

According to Amumpe, about 60,000 hectares have been planted by tree

A healthy pine forestfarmers and the NFA, but this is less than half of the amount of wood needed to meet the timber needs of the country.

He also points out that planting of trees suffered during the years of political turmoil and civil unrest in Uganda in the 1970s and 1980s. SPGS and NFA resumed aggressive tree planting in 2004.

“Most of them planted pine trees, which grow in about seven years. The country will have another shortfall in 10 years’ time,” says Amumpe.

“A few farmers planted eucalyptus, but this is too small to meet the demand for timber.”

Driven by such concerns, Kiwuso is working round the clock to get the solutions in order to tame the pest, which has developed a wide appetite for exotic coniferous trees, yet Ugandans need the same trees for timber for various reasons.

“We will return to Kiriima to assess how we can release some of the predators to reduce the moth pest,” says Kiwuso.