In a tiny village in Nyandurua, not far from the Aberdare Forest, dozens of potato farmers shelter under a tent to avoid the biting cold descending from the hills as they follow lessons on potato farming.
The demonstration is being conducted on Francis Giteru’s farm, a small-scale potato farmer in Gathara Village, who has been growing the crop for the past 20 years.
When we met Mr Giteru at his farm, he is wrapping the potato seeds in brown papers made of banana fibre—one seed in every paper—before planting them in the soil.
Mr Giteru says smallholder potato farmers face challenges accessing clean certified seeds, so they share or recycle them, leading to the spread of pests and diseases from one farm to another.
When he started growing potatoes in the early 90s, he could easily harvest 100 bags from an acre of land. In the mid-2000s, his harvest dropped to 40 bags and now he only manages 15 to 18 bags from the same piece of land.
“Besides the seeds, the soil has grown infertile and less productive and pests such as potato cyst nematodes have also become widespread,” the farmer said. Mr Giteru only learnt that his farm was infested by nematodes last year following a survey by researchers, as they are very tiny pests that cannot be easily spotted by untrained eyes.
“The scientists tested my soil and found it had 25 percent nematodes infestation,” he says.
He is among thousands of potato farmers in Kenya betting on the new technology where seeds are wrapped in a banana fiber paper which has been treated to tackle the deadly potato cyst nematode pest. The technology stops the soil nematodes from attacking the potato seed.
Last year, researchers under the NemAfrica programme, a nematology unit at the International Institute of Tropical Agriculture (IITA) and the International Centre for Insect Physiology and Ecology (Icipe), concerned about the declining potato yields in Kenya conducted a study in 22 potato growing counties.
They found that potato cyst nematode was a significant contributor in the decline potato yields. Nyandarua country was the worst affected by the pests.
“We have used the banana fibre papers for one season and it has been a success. We planted three phases, in one plot we used the paper wrappers, the other one we used the wrappers that didn’t have pesticide treatment while on the third plot we did not use any intervention,” says Mr Giteru who was among a few farmers selected to be part of the pilot.
He says the tiny plot that had wrapped potato seeds produced 50 kilogrammes while the other one produced 25kg.
“It is not easy to tell when your crops have been attacked by the nematodes just by looking at the tubers or its leaves. The tubers do not show any damages or change in taste,” he says. But the pests damage the potato crop, significantly reducing yields and tuber sizes, and consequently impacting farmers’ income.
Ditch potatoes
Jesse Kamutu, a potato seed and tuber producer from Kinangop, says farmers in the county have abandoned potato farming for other crops due to reducing yields and poor quality of produce.
Harrison Mburu, a research assistant at IITA, says when the nematodes hatch their young ones, they target the roots of the crop in the first two weeks after planting.
“They take up the nutrients meant for the seed. They affect the plant root system resulting in stunting, and sometimes yellowing of the crop,” he says, adding that most of the time if the crop is uprooted, one cannot see the nematodes but one can notice small tubers that are not well-formed.
For years, farmers have been using nematicides to control the pests, but the use of the chemicals was banned due to their adverse effects on the environment.
The pests are introduced to the soil through shared farm machines and seeds, hence proper farm management and good practices can reduce the pests.
“Planting clean seeds in a highly infested soil doesn’t help. The nematodes can stay in the soil for even up to 30 years. We encourage farmers to leave the land fallow or rotate their crops to break the cycle,” he advised.
The banana fibre paper was initially given to farmers for free for the study but the researchers say it will cost as small fee when they are officially launched in the next few months.
According to the researchers, certain potato varieties such as Shangi –which is very popular with local farmers-are very susceptible to the nematodes. Unfortunately, farmers are reluctant to plant other varieties such as Money II and Jelly which are more resistant, because Shangi is in high demand.
The NemAfrica is currently assessing new potato varieties that are resistant to the potato cyst nematode (PCN) pest.
The eight new lines of potato sourced from Scotland arrived in March this year before being certified by the Kenya Plant Health Inspectorate Service (Kephis) for planting and testing under the local conditions.
Prof Danny Coyne, a soil health scientist at IITA, who has been leading efforts to assess the new lines says that besides their resistance to potato cyst nematodes, the specific lines were selected based on attributes preferable to local farmers.
“The lines are early maturing and have a short dormancy, which are key characteristics of Shangi, as well as being high yielding compared to the current local varieties,” says Prof Coyne.
