Ipomoea in Kajiado: Understanding the Invasive Weed Threatening Kenya's Rangelands

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In parts of Kajiado County, an invasive vine known as Ipomoea Carnea has spread across grazing land that pastoral families have relied on for generations. In some of the county's

hardest-hit areas, researchers estimate it now covers between 60% and 80% of pastureland, replacing grasses that livestock depend on and making an already challenging climate even harder to live with. That isn't just an environmental problem. In a county where livestock underpin livelihoods, it becomes an economic one too.

Yet despite its growing visibility, Ipomoea remains surprisingly misunderstood. Is it simply another weed? Why has it spread so quickly? Why has it proved so difficult to control? And if communities have been fighting it for years, why does it continue to expand?

This article brings together what current research tells us and where important questions remain unanswered.

What is Ipomoea?

Ipomoea refers to a group of fast-growing vine species that thrive in degraded landscapes. In Kajiado, these plants spread rapidly after the rains, forming dense mats that compete aggressively with grasses for sunlight, water and nutrients. They spread fast in rangelands that have been degraded through heavy grazing or other forms of disturbance.

From a distance, an invaded pasture can still appear green. Up close, however, much of that vegetation is no longer usable forage. For pastoral households, the difference matters.

How widespread is the problem?

The most comprehensive published assessment of Ipomoea invasion in Kajiado remains a 2015 study by researchers from KALRO's Arid and Range Lands Research Institute.

Working with pastoralists, farmers, government officers and community representatives, the researchers combined interviews, focus group discussions and field visits across two of the county's most heavily affected clusters: Olbelbel and Sajiloni in Kajiado Central, and Mashuru and Nkatu in Mashuru Division.

Their findings were striking.

Field observations estimated that Ipomoea covered 60–80% of pastureland in the worst affected locations. Community members independently estimated invasion levels at 65% in Kajiado Central and 50% in Mashuru. Cropland was far less affected, with invasion estimated at around 10%, largely because crop farming is relatively limited in these areas.

More than a decade later, there is still no comparable county-wide survey showing how those figures have changed. That means the available evidence provides an important baseline, but also highlights the need for updated field data.

Why does Ipomoea matter?

Pastoral livelihoods depend on healthy rangelands.

Across Kenya's ASALs, livestock production supports household incomes, food security and local economies. When grazing land deteriorates, the effects extend well beyond ecology.

Communities participating in the 2015 study consistently identified reduced pasture as the single most significant impact of Ipomoea invasion. Researchers also documented several related concerns:

• Dense Ipomoea growth suppresses or outcompetes grasses that livestock normally graze.

• Livestock generally avoid feeding on the green plant, reducing the amount of usable

  pasture available.

• During prolonged dry periods, when little else remains green, hungry animals may consume the plant, increasing the risk of poisoning.

• Communities reported that heavy infestations restrict livestock movement and grazing patterns.

The result is a gradual reduction in the productive capacity of grazing land, placing additional pressure on households already coping with drought and climate variability.

Why is it spreading?

The research points to a consistent pattern.

Ipomoea is not randomly invading healthy grasslands. It establishes most successfully where land has already been disturbed or degraded. Community members identified overgrazing and changing climatic conditions as the main drivers behind its spread, with many recalling the 1997–98 El Niño period as a significant turning point in local observations of the weed's expansion.

The plant itself possesses many of the characteristics common to successful invasive species. It grows rapidly, produces large numbers of seeds capable of surviving dry conditions, and competes aggressively with native vegetation. Those traits become especially effective once healthy pasture has already been weakened.

In other words, degraded land creates opportunities for Ipomoea and once established,

Ipomoea makes it even harder for healthy pastures to recover.

Can it simply be removed?

Communities have not ignored the problem.

Over the years, pastoralists have tried manual uprooting, hand removal of young seedlings, chemical spraying and other locally adapted methods. According to the study, only manual removal showed consistent short-term success, and even then, it required repeated follow-up together with pasture restoration to prevent the weed from returning. Chemical control methods trialled in the study areas produced little success.

For many households, the challenge is also economic. Manual clearing is labour-intensive and can cost around KES 4,000 per acre, placing large-scale control beyond the reach of many families.

The research therefore reaches an important conclusion: controlling Ipomoea is not simply about removing the weed. It also requires restoring the health and resilience of the rangelands themselves.

Looking beyond the weed

Much of the public conversation around Ipomoea focuses on eradication. The research

suggests a more complicated picture.

The weed is both a symptom and a driver of degraded rangelands. Removing it without

restoring pasture often creates conditions for reinvasion, while restoring healthy grazing

systems makes landscapes more resistant over time.

That shift in perspective is increasingly shaping how researchers, practitioners and communities think about long-term responses.

At Narresho Alliance, we believe understanding the problem is the first step toward solving it. In the next article, we'll take a closer look at just how extensive the invasion has become across parts of Kajiado and what those numbers really tell us about the state of the county's rangelands.

References

● Kidake, B. K., et al. (2015). Assessment of the Status of Ipomoea Weed Infestation in Kajiado County, Kenya.

● Narresho Alliance. (2026). Circular Bioeconomy Policy Brief.