Kefri battles new invasive dodder weed

It also attacks ornamental, native plants, trees and can reduce aesthetic value of landscapes

In Summary
  • Dodder attacks many plants and can cause heavy economic losses.
  • Kefri says dodder in Kenya is rapidly spreading and has already been observed in about 12 counties, mostly in the Eastern, Western, and Rift Valley.
A tree attacked by the field dodder
A tree attacked by the field dodder

As scientists battle invasive species such as mathenge, other weeds are coming up with the latest weed known as dodder, giving researchers sleepless nights.

The Kenya Forestry Research Institute acting CEO, Dr Jane Njuguna, says dodder, an invasive species, is the latest invasive plant species that is a major threat to various ecosystems.

“We undertook research for almost two years at Michuki Park to explore the possibilities of controlling it with chemicals. However, chemicals have dangerous effects,” Njuguna said.

Dodder attacks many plants and can cause heavy economic losses.

Kefri says dodder in Kenya is rapidly spreading and has already been observed in about 12 counties, mostly in the Eastern, Western, and Rift Valley.

It has become a threat not only to trees but also to crop yields, thereby compromising both biodiversity and food security.

Dodder also attacks ornamental and native plants and trees and can reduce the aesthetic value of landscapes.

The species is found on a broad host range of both native and exotic plants, including trees, shrubs, hedges, and important cash crops such as tea and coffee.

Njuguna says her institute has developed a fact sheet on how to control the weed.

“We recommend manual destruction, whenever you find it, please destroy it,” she says.

The Kefri fact sheet shows that attempts to control dodder using natural enemies (bio-control agents) have not been successful anywhere in the world.

Njuguna says controlling dodder is a hard task as the weed is easily moved by birds, as they like eating seeds.

The fact sheet calls for mapping out the extent of the dodder parasite in the country to identify hot spots and other levels of infestation for immediate intervention as well as determine the socio-economic and environmental impact of the parasite in hot spot areas.

It also calls for the carrying out of molecular identification to determine species present in Kenya.

The KEFRI National Forest Health Research Strategy (2018–2023) identified invasive plant species as one of the forest health issues of concern.

The institute says dodder is currently spreading fast in Kenya and, if left unmanaged, is likely to threaten a wide range of trees and crops and may affect food security.

It said that rigorous awareness creation is critical to imparting knowledge for the successful management of dodder.

Apart from dodder, Kefri is also battling with other invasive species, such as prosopis, also known as mathenge.

Njuguna said the institute has developed a strategy and an action plan.

“We are now in the process of developing a policy because prosopis is a national issue as it is on everybody’s land and it belongs to none. We are doing a policy on how to manage prosopis through utilisation and also embarking on utilising mathenge for commercial production by actually planting it,” Njuguna says.

In 2006, the members of the Ilchamus community moved to court to challenge the government for letting the killer weed keep growing. In tow was a goat that they claimed had lost its teeth to the weed.

Many then laughed about the move by the community. The community, however, had a point.

The representatives dragged the state to court and sought to be compensated for the losses they had incurred since the introduction of the weed.

The court then instructed the formation of a tribunal to investigate the claims by the community. Nothing happened thereafter.

Kefri, through the Environment ministry, has, however, been trying to tame the challenge.

In June 2022, the state declared mathenge weed a national disaster because it takes over cropland and pasture and injures animals.

In 2014, a foreign investor tried to set up a multi-million shilling Cummins Cogeneration industry to make use of the weed to generate electrical power, but it closed shop immediately due to logistical hitches.

Kefri says mathenge was introduced in Kenya in the 1970s, among other species from South America to rehabilitate the Arid and Semi-Arid Areas.

This was due to its resilience, fast growth rate and its many uses for fodder, honey production, shade, windbreak, firewood, building poles among other uses.

The tree however aggressively invaded areas of indigenous vegetation and manifested a negative impact on rural landscapes as well as on human and livestock health.

Kefri says the largest biomass of Mathenge in Kenya is found in Tana River, Turkana and Baringo counties.

Taita Taveta, Samburu, Isiolo, Mandera, Marsabit, Wajir, Kajiado, Migori counties, and Malindi are other areas where the weed is found.

Today, the weed is spreading like wildfire.

In Baringo South, for instance, the fast-growing vegetation now covers an area of 50 km2, with 13 villages affected.

Apart from affecting humans, the hardy weed has rendered livestock toothless, blocked access roads and waterways, ravaged people's land, and caused its roots to crack the walls of houses.

Kefri says the weed has some uses, such as Prosopis pods, which are a valuable source of carbohydrates, sugar, and proteins for livestock and, occasionally, the human population during dry seasons.

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