The Potato Cyst Nematode (PCN), known by its scientific names Globodera rostochiensis or Globodera pallida, is a quarantine pest, meaning that in places where it is discovered, no potato production or marketing is allowed to stop the pest from spreading.
The PCN pest destroys between 80-100 per cent of a potato crop and can remain in the soil for up to 30 years once it has established itself.
Farmers start experiencing losses from seven to 20 years depending on the climatic region affected by the pest.
Up to now, there is no known chemical or biological pesticide that can control the pest.
The only control measure is to stop potato production for about seven years to reduce pest levels in infested farms, according to scientists.
Already, farmers in Nyandarua where the pest was first identified in September 2014 have reported a drastic reduction in potato yields of 60 to 80 per cent. The region produces more than 40 per cent of Kenya’s potato crop.
Scientists at Kenya Agricultural and Livestock Research Organisation (Kalro) and the Kenya Plant Health Inspectorate Service (Kephis), say the pest may have been introduced into the country earlier going by the level of infestation they have found in affected areas.
Potato production in the country has been going down in the past four years with key producing areas such as Meru, Kirinyaga, Murang’a and Nyeri being forced to import potatoes from as far as Elgeyo Marakwet and Mount Elgon. A bag of potatoes is going for Sh3,000 in most of the producing areas.
Last year, the Ministry of Agriculture, Livestock and Fisheries, together with Kephis, took soil samples in 18 potato producing counties where scientists established the presence of the pest.
Researcher James Mwangi checks a potato plant for the PCN pest in Tumaini Nyandarua County.
Among the counties with the pest are Nyandarua, Narok, Bomet, Kericho, Nakuru, Uasin Gishu, Elgeyo Marakwet, Trans-Nzoia, Kiambu, Laikipia, West Pokot, Bungoma, Kakamega, Nyeri, Kirinyaga, Embu and Meru.
A stakeholder meeting organised by the National Potato Council at ICIPE last week was told that a scientific survey planned two years ago to ascertain the severity of the pest has been delayed for lack of funds.
The survey that was to cost Sh18 million would help the government plan intervention measures to contain the pest.
The potato pest may have spread fast to all potato growing areas because farmers exchange potatoes across the country for growing due to lack of certified seeds. The government can only supply 1 per cent of potato seed.
To bridge the gap in seed production, the government has on various occasions allowed the importation of potato tubers mainly from Netherlands against phytosanitary regulations.
Scientists have complained about the relaxation of this requirement saying the imported seeds have the potential to introduce new diseases and pests.
Scientists at Kephis and Kalro say the country cannot produce certified seeds for farmers because Kalro’s basic seed production unit at Tigoni, including potato multiplication farms across the country, are also infested with the pest.
Other countries in Africa where the pest has been identified, but is under quarantine include Moroco, Libya, Tunisia, Senegal and South Africa. Kenya is yet to declare the presence of the pest as required by the International Plant Protection Convention and Food and Agriculture Organisation (FAO).
Potato is Kenya’s second most important crop after maize.
James Mwangi, a researcher and assistant lecturer at the Department of Biological Sciences at Chuka University, who was the first to come across the pest while working on his Masters thesis in Nyandarua in 2014 said that on some farms, the pest population was as high as 260 cysts per 100 cubic centimetres of soil, which is enough to wipe out an entire potato crop.
His samples underwent molecular analysis at Kenyatta University, a DNA sequencing at Inqaba Biotech Company in South Africa and Bonn University in Germany, all of which confirmed the pest to be Globodera rostochiensis.
Wachira Kaguongo, the CEO of National Potato Council of Kenya, which is heading a task force on the disease, says the institution is working with a number of donors, including FAO to raise funds for undertaking a nationwide scientific survey in the next few months.
He said a proposal to seek funds for the survey that is expected to cost about Sh18 million was to be finalised yesterday.
The survey is expected to provide scientific evidence on the severity of the PCN in all potato growing areas.
“The findings of this survey are very important as they will provide information that can be used to plan intervention measures that will be used to contain the pest to stop its spread,” he said.
Potato is grown by more than 800,000 farmers. More than 70 per cent of potatoes are consumed in urban areas providing about Sh50 billion to farmers, traders, transporters and processors.