Scientists in Kenya have discovered an organic way of protecting potatoes from the invasive and highly destructive potato cyst nematodes that attack planted seed causing major yield and financial losses.

Known as “wrap and plant’’, the inventive method involves enclosing potato seed in a thick absorbent paper made from banana fibre before planting. The banana leaf casing alone protects the potato plant from potato cyst nematodes (PCN) damage.

PCN is a long roundworm that lives in the ground and attacks potato seed. PCNs are emerging as the most important threat in potato production in East Africa, where the crop features prominently as both a food security and income-generation crop for millions of smallholder farmers.

Researchers, led by the International Centre of Insect Physiology and Ecology (Icipe), the International Institute of Tropical Agriculture (IITA) and North Carolina State University, have published their findings in Nature Sustainability.

A recent study found cysts in 71.8 percent of soils in potato-growing counties in Kenya, with Nyandarua — the key potato-growing zone — recording the highest PCN field-incidence at 47.6 percent.

First detected in Kenya in 2015, PCN has now widely spread across the region, including in Rwanda and Uganda.

“Our estimates show that PCNs are causing potato production declines of more than 60 percent, with projections indicating an even worse scenario,” notes Prof Danny Coyne, a soil health scientist at IITA. “The current study demonstrates that the ‘wrap and plant’ paper, whether containing nematicides or not ... can increase potato yield by up to five times.”

“The banana-fibre has unique sponge-like properties. Thus, through a process known scientifically as ‘hydrogen bonding’, the ‘wrap and plant’ paper is able to soak and physically bind the critical chemical signals released by potato crops that allow the PCN to hatch, find and infect the plant’s roots,” said Prof Baldwyn Torto of Icipe.

The researchers explain that the banana-fibre characteristics make the ‘wrap and plant’ paper dense, rigid and sturdy, such that it remains intact in the soil while also allowing the plant’s roots to germinate and thrive. Although the paper is durable, it is also biodegradable, and it eventually decomposes.

This may aid in protecting biodiversity by reducing the use of chemical pesticides and the clearing of forests to create more productive fields that are free of nematodes and other pests.

The scientists are urging farmers to adopt this novel method of planting cultivars as a containment or management strategy in the country and ultimately across the region to mitigate the PCN threat.

As Prof Baldwyn Torto, Head, Behavioural and Chemical Ecology Unit, icipe, explains, the most significant discovery of this study was that, even without the nematicides, the ‘wrap and plant’ technology protects potato from PCN damage

“Initially, we aimed to understand whether the ‘wrap and plant’ technology can help to improve the delivery and effectiveness of nematicides, the chemical agents that are used to control parasitic worms that damage crops, such as nematodes,” says Juliet Ochola from Kenyatta University, in Kenya, who was involved in the research as part of her MSc studies. The research was co-supervised by icipe and IITA.

“We established that when loaded with ultra-low dosages of nematicides, the banana paper enables the chemicals to be released in a slow and sustained manner and in very low but effective concentrations. The paper also facilitates the nematicides to be conveyed specifically to the root zone of the potato plants; the infection site of the nematodes, thus preventing contamination to non-target areas and organisms,” she adds.

“The ‘wrap and plant’ technology is a promising boost for food and nutrition security as well as household incomes, as it will help to safeguard production of potato, East Africa’s second most important staple crop. It also contributes to the vision of a circular economy by transforming banana-fibre, often regarded as an agricultural waste and a nuisance for farmers, into a raw material for pest control innovation.

This could create opportunities for entrepreneurs and farmers. Besides reducing overuse or misuse of chemical pesticides, the ‘wrap and plant’ technology will also support environmental protection by assisting to curtail the growing trend where farmers are compelled to clear forests in an unsustainable manner to create productive fields that are free of PCNs and other pests.

Overall, this breakthrough in PCN control demonstrates an environmentally-friendly way to counter disruptions in sustainable food systems,” said a press release from icipe on Tuesday.