Research points out cause of poor Irish potato yields

Late blight disease caused by the fungus P. infestans has been identified as the major cause of low Irish potato yields to farmers in Kenya.

The disease causes serious crop losses of up to 22 per cent and has become a major concern to scientific researchers.

Researchers argue that integrating Di- Ammonium Phosphate fertiliser (DAP) with vermiliquid foliar spray could be the best treatment for controlling late blight disease in Irish potatoes.

• How to handle chicken before slaughter
• Role of water in animal health and productivity
• 9 causes of decreased egg production in flock
• In Kenya, livestock farming stands as a testament to tradition and resilience

Irish potato (Solanum tuberosum L.) is grown globally, however, poor yields in Kisii county have been attributed to late blight disease which is rampant in the region.

Depletion of the beneficial soil microbes and excessive use of inorganic fungicides have led to the resistance of late blight disease pathogens, raising alarm for alternative treatments.

Consumption of potatoes has been on the rise with the increasing urbanization and growth of the fast-food industry.

It is approximated that over 60 per cent of the fresh produce grown and traded by urban traders in Kenya is absorbed by fast-food outlets.

In the research, Response of Solanum tuberosum L to different soil amendments and foliar sprays in the control of Phytophthora infestans in Kisii, published in October 2021, Mokeira Lilian, Dr Nyangeri Jason and Dr Ondari Erick say despite its importance, potato production is constrained by soil degradation, lack of quality certified seeds, as well as pest and disease management.

Principal research, Mokeira, a Masters Student in Plant pathology Kisii University and her two supervisors Dr Nyangeri and Dr Ondari; Faculty of Pure and Applied Science, Kisii University, argue that Irish potato is the second-most important food and cash crop after maize in Kenya.

“It plays an important role as a staple food among small-scale farmers as well as alleviating poverty through income generation."

Approximately one million farmers grow potatoes in Kenya, while over 2.5 million Kenyans are employed along the potato value chain either directly or indirectly.”

The Irish potato yield constraint has been attributed to, among other factors, poor nutrient management strategies, inadequate cropping systems, accelerated soil erosion rates, and the high cost of inorganic fertiliser.

They established that in the review on constraints of Ware Irish potato in Kenya, the soils are more acidic in the growing regions due to the inorganic fertiliser frequently used.

The research also illustrated the severity of late blight disease on Irish potatoes treated with compost manure plus compost tea (CM/CT).

Compost tea performed poorly as a foliar spray in the control of late blight disease in Irish potatoes with the least disease control of 18 per cent. 

In terms of soil amendments, D.A.P fertiliser gave the highest marketable tuber yields and this is because it contains high amounts of Nitrogen, potassium and Magnesium which are key limiting nutrients to potato production.

According to the Kenya Agricultural and Livestock Research Organization, more than 800,000 smallholder farmers cultivate the crop. Potato production in Kenya is valued at Sh50 billion.

Hosea Machuki, the CEO of Fresh Produce Exporters Association of Kenya, says the average annual potato production is two million to three million tonnes. "The sector needs additional research funding to come up with varieties that are high yielding and disease-resistant. Without research, there is no development."

Machuki said Kenya has the potential to produce eight million tonnes of potatoes annually, but the current annual production is two million tonnes, sometimes less.