Wild potato genes help East African farmers cut pesticide costs and fight late blight

For many smallholder farmers in the tropical highlands of East Africa, the dream of a bountiful potato harvest is increasingly overshadowed by a 'chemical tax.' Disease pressure keeps farmers trapped in a costly cycle – spraying more pesticides each season, yet earning less at each harvest.

Peter Njuguna, a potato farmer and social media content creator in Njoro, Kenya:

"There is a big problem with inputs. Costs are rising by 50 to 60 percent. But farmers are not making much profit."

The Heavy Cost of Protection

The culprit is often late blight, the most destructive potato disease worldwide. Late blight attacks potato plants and their tubers and can destroy a potato field in a matter of weeks. To save their crops and stay competitive with other countries, farmers in Kenya and Uganda spray pesticide 10 to 15 times per growing season. Sometimes they spray as often as every five days during the wet season.

These chemicals put pressure on the environment and pose health risks. They are also a heavy financial burden, often accounting for 15 to 25 percent of total production costs. In Kenya and Uganda, potatoes contribute significantly to the food security and household incomes of over a million smallholder farmers and their families. In many communities, potatoes are both a staple food and a cash crop.

Thiago Mendes, a breeder with the International Potato Center:

"Spending hundreds of dollars per hectare on pesticides can mean the difference between a profit and a loss. When we ask farmers what they value most in new varieties, they rank resistance to pests and disease above all other traits."

Potato farmer Peter Njuguna shares observations with fellow growers during the field evaluation in Njoro

Recalling the Wild Traits

Over time, many of the cultivated varieties in East Africa have lost their natural resistance. The solution to this chemical dependency may lie in the potato’s wild relatives. The first potatoes were domesticated in South America between 8,000 and 10,000 years ago, and the Central Andes remain home to more than 150 wild relatives of the crop. 

Many produce tubers that are too small or bitter to eat, but they carry valuable traits. Over thousands of years, these hardy plants have evolved natural tolerance to heat, drought and freezing temperatures, as well as genes that help them resist pests and diseases. 

The Crop Trust BOLD project is enabling scientists like Thiago to bring these traits back. By crossing wild species that carry natural resistance genes with cultivated potatoes, breeders are creating pre-breeding lines that can naturally withstand late blight. These new varieties can significantly reduce the need for pesticides.

 

Potato farmer Peter Njuguna shares observations with fellow growers during the field evaluation in Njoro

From Genebanks to Fields

This is more than laboratory science. It is a collaboration with the people who know the land and what best grows here. At BOLD breeding trials in Kenya, farmers like Peter participate directly in participatory variety selection. They grow different varieties and walk the rows, evaluating which plants look the healthiest and will likely meet market needs. The right variety can mean fewer sprays, lower costs and the difference between profit and loss. 

Thiago Mendes:

"Our mission is to connect this diversity from the genebank and make it available to the farmers."

By bringing Andean genetic traits into breeding programs in Kenya, the project is developing potato varieties better suited to the pressures farmers face in their fields today. For Peter and thousands of potato farmers in East Africa, the search for better potatoes is key to breaking the chemical tax cycle. Finding a variety that can hold up in the field with less spraying can improve lives, livelihoods and food security in Kenya and around the world.