SPECIAL REPORT: Farmers bank on new device to combat cassava diseases

Researchers clarify technological issues to a farmer in Bagamoyo

Dar es Salaam. Asha Mohamed and her fellow Kiromo villagers in Bagamoyo District, Coast Region, have been losing heavily as cassava mosaic disease has been destroying the crop.

“This is the third year since our crops have been dying off. We could plant well but during harvest time, the crops wilt, they are attacked by white insects. They wilt, sometimes,’’ she laments.

“We don’t know what causes this. When the crops dry, we wait for another season. When the rains come, we plant again and the same bad trend reccurs.

“The lucky farmers can harvest half of the acre that was planted. The other half dies,” she told The Citizen recently in Bagamoyo.

However, her hopes of having better yields in the coming seasons have been revived.

Researchers have introduced a device, known as the Minion nanopore that can detect viruses that destroy cassava.

Dr Joseph Ndunguru, the head of Selian Centre of the Tanzania Agricultural Research Institute in Arusha, says the nanopore technology enables experts to detect viruses on the spot and suggest a solution.

Dr Laura Boykin of the University of Western Australia, who was also a team member, says the nanopore technology has also been used to detect Ebola and Zika sequencing around the world and it has shown success.

“So we decided that we should bring it to farmers in East Africa, which means they will be able to eventually have more food. It is an empowerment to people having a technology. It means you don’t have to rely on people; you can do it for yourself.

“This technology is amazing. We are able to do analysis within a short time and we able to provide feedback to the farmer.”

How Minion nanopore works

Explaining how the technology works, Mr Charles Kayuki, who participated in the research, says the technology is simple and can give results within a short time, without taking samples to a laboratory for examination.

“Minion nanopore is a device made by the Oxford Nanopore Technologies of the United Kingdom. It is a portable DNA sequence and can detect diseases and its agents.

Genetics is the key factor to understand the origin of living organisms. Every organism has been created by cells which is the source of life.

Within a cell there is a nucleus which keeps DNA, which also keeps genes which have genetic information and behaviours of a particular organism.

Genes are made up of four bases which are thymine (T) cytosine(C), guanine (G) and adenine (A). A gene has arrangements of bases which enable to identify organisms.

So when you put a piece of plant into the Minion and then you insert it in a computer, it can read arrangements of a plant and also of the viruses or fungi or bacteria affecting a particular plant.

So it is easier to carry the Minion with a laptop to farm and cut the affected organ of the plant and put to the Minion and detect what type of organism whether a virus or bacterium or fungus is affecting the plant and so it is easier to suggest the possible solution.


Mr Kayuki says the Minion has made it possible to group pests and diseases in zones and by so doing field officers can understand a proper variety to use for a particular zone.

“If you want to know which diseases affect the Lake Victoria Zone, for example, you can take a sample and make a sequence through the Minion and so you understand how the zone is affected and suggest what type of seed to be used or a type of pesticide to a particular zone.

“If you take samples from 25 regions after making sequencing you can figure out which zone or a region has a particular type of diseases and so which solution should be taken.”

Mr Kayuki says they have done some experiments in various areas, including Bagamoyo, and they took 24 hours to detect types of microorganisms affecting crops and advise farmers on better ways to undertake.

In Musoma and Butiama districts in Mara Region, the Minion has also proved effective.

“We also went to Selian in Arusha to train them on how to use the technology. We’ll also introduce it to the University of Dar es Salaam.”

After exhausting in Tanzania we went to Kenya and Uganda to introduce the technology.

He also said that Tanzania has been the champion on using the technology in Africa.

He suggests to the government make sure that all research institutions have the technology to help farmers to wipe out crop diseases.

The researchers now plan to expand the project because it is estimates that 800 million people worldwide depend on cassava, which is threatened.

The project aims at reducing the risk of crop failures and help preserve livelihoods.

Other techniques

The technology could be similar in some cases with the polymerase chain reaction (PCR), which is use to amplify amounts of DNA (and in some instances RNA) located in or on almost any liquid or surface where DNA strands may be deposited.

Given that, every human, animal, plant, parasite, bacterium, or virus contains genetic material such as DNA (or RNA) sequences that are unique to their species, and to the individual member of that species.

According to experts, PCR is a method used to amplify (make many more identical copies) of these unique sequences so they can then be used to determine with a very high probability the identity of the source of the trace DNA or RNA found in or on almost any sample of material if a sample contains segments in it.

However, the PCR amplification is only part of the identifying test. This comparison of unique segments is often done by placing PCR-generated nucleotide sequences next to known nucleotide sequences from humans, pathogens, or other sources in a separating gel.

There are also various techniques to underscore pest and diseases which affect plants in the farm. According to various sources the common techniques which a farmer can use is through observation in which a farmer can follow behaviours of pests including life cycle from an egg, larva, pupa and adult.

The farmer can also study when does a pest attack a plant, is it during a day or night? Is it during rainy season or drought?

Another observation should be made on which part of a plant is most attacked. It could be roots, or stem or leaves or flowers or seeds. Also he could underscore the ways in which diseases are communicated like the soil, air or seeds.

These ways could help a farmer to at least how pests attack plants and so what type of measures should be taken.