Fighting the banana bacterial wilt

Banana Xanthomonas Wilt (BXW), or banana bacterial wilt (BBW), was first reported in Uganda in 2001. It has since spread to many banana-growing regions in Kenya, Tanzania, Rwanda, Burundi and DR Congo. Banana farmers in central and western parts of the country have been hit most. But there have been interventions to sensitise them to apply sanitary measures to control spread of the disease.

Masaka District, which was reknown as a banana growing region, has been facing declining production. The farmers there have turned to cassava because the banana wilt disease seemed to be unmanageable.

Check the spread
Deborah Katasi, acting agricultural extension officer, says when farmers realised the disease is destroying their crops, they reported to the district agricultural office. The officials immediately went on ground to establish the danger caused by BBW. They did this in consultation with officials from ministry of agriculture and National Agricultural Research Organisation (Naro).

Later, the district agricultural officials liaised with scientists from Mukono Zonal Agricultural Research and Development Institute (Muzardi), who came to sensitise farmers about the sanitary measures to check spread of the disease. In addition, Food and Agriculture Organisation (FAO) distributed tissue culture seedlings, as clean planting material, to help farmers replenish their plantations.

A district task force team was formed at local council (LC) level with more personnel, but seven members for those at the sub-county and village levels. Once a farmer’s field is identified with disease infection, the task force will be assigned a day, depending on the village, to go out and help the farmer cut all infected plants.

A farmer who is keen in following the sanitary measures will be in position to rejuvenate his or her farm sooner than later. But those who do not follow the process and continue using infected farm tools, gave up on growing the crop. It is also a requirement that once the task force carries out its duty, the team makes a report to the district office. This is circulated to the partner institutions such as the ministry and Naro for possible solution.

Partnerships
In the report by scientists at National Agricultural Research Laboratories (NARL) Kawanda, it was stated that since the disease was discovered, banana farmers have used several cultural methods such as sanitary measures to control its spread without much success.

Scientists then explored a solution and this led to the birth of the Banana Bacterial Wilt project. This involves developing BBW-resistant varieties of, namely, sweet banana, East African highland banana (commonly known as matooke) for the farmers.
The BBW project is a public-private partnership that brings together African Agricultural Technology Foundation (AATF), International Institute of Tropical Agriculture (IITA) and Naro. The former solicits royalty-free genes to be incorporated into the banana using biotechnology.

In 2004, IITA and Naro scientists started developing transgenic bananas resistant to BBW in a joint project funded by Gatsby Charitable Foundation. AATF joined the project in 2005 and successfully negotiated for two genes namely plfp and hrap from Academia Sinica in Taiwan for use by the scientists.

Making progress
The three organisations agreed to work together and therefore signed an agreement in 2009 to guide the partnership. IITA and Naro were responsible for developing, transforming and evaluating the bananas for resistance to the disease. AATF’s role to coordinate the partnership and provide expertise in management of intellectual property and regulatory issues.

The project then commenced with funding from AATF and additional support from Gatsby Charitable Foundation, Usaid and Uganda government. The research work is being carried out at NARL Kawanda using farmer-preferred varieties.

The progress made is positive following the successful work in the laboratory and subsequent carrying out of the first confined field trial at Kawanda.
BBW project partners met in July 2012 in Kampala to review progress made and to plan for future activities.

During this meeting, the scientists reported that their endeavors have generated several lines of the apple banana, popularly known as sukali ndizi, and matooke. These showed resistance to the disease after they inserted a gene extracted from sweet pepper.

My mother was depressed

I am Khalida Nankya, daughter to Namwandu Misusera Mwanje, from Nabinene village in Bukoto South, Masaka District, who suffered a stroke after losing her plantation to BBW.

Around 2012, many farmers realised there was a “strange” disease wiping out bananas including my mother’s. We did not know how to go about it but to cut down infected plants but the disease kept on spreading.

My mother grew banana on one and half acres. It was mainly matooke both for sale and home consumption. But now see the farm! We have tried to plant cassava.
She got a stroke, which was a result of depression arising from losing her banana crop. What I realised with this disease is that it first affects the trunk right from the roots before spreading to the leaves and fruits. It begins to dry up until it withers and falls down. There is also a bad smell from the infected parts. What we usually do is to uproot the plant but leave the young ones. These, sometimes, tend to survive.

In some cases, the entire plant even where other young plantlets tend to shoot out is uprooted to avoid further spread. The disease affects all banana species be it Mpologoma, Nakitende, Nakabululu and sweet banana (sukari ndizi). Some farmers pour urine and ash to remains of the uprooted trunk while others cover it with soil.

Despite effects of the disease, i apply the best practices

My name is Leocardia Namata, a farmer in Kasango Village, Bukoto South in Masaka. I am married with seven children. But this farm with one and half acres of banana belongs to me as an individual. You can see how keen I am in looking after it.

I do this by applying good agronomic practices to curb the disease because I use proceeds from the farm to cater for my children. Despite the disease burden, the soils here have become infertile because I am over-tilling it. I lack money to purchase fertiliser, which I believe if applied would boost the soil.

Apart from mulching, I also make sure the spacing of the plants are adequate to avoid spread of the disease. I am intercrop banana with coffee and I think this also helps in controlling the disease.

I understand scientists at Kawanda are breeding varieties, which are resistant to disease. But I do not know how I can get the seedlings from them. But what I know is that government and Members of Parliament are supposed to ensure that these seedlings are availed to us farmers.

Despite this effort, the disease still affects my plants. I am getting low yields because I used to harvest 20 bunches in a month but now I get only five bunches.

What is the bacterial wilt?

Dr Jerome Kubiriba, who heads the team at Kawanda, explains that banana bacterial wilt is a lethal disease caused by a bacterium called Xanthomonas campestris pv. musacearum. If left uncontrolled, it can cause severe yield losses.

Before 2001, it was found only in Ethiopia, where it affects bananas and its close relative called Ensete ventricosum. It has since spread to the Great Lakes region of eastern Africa.

The bacterium is transmitted to new plants by insects and contaminated tools. Symptomless banana suckers can also spread the disease. The disease causes loss both through death of the plant and rotting of the fruit. The leaves gradually turn yellow and start looking lifeless as if they were melting under intense heat. They eventually turn brown and die.

In flowering plants, the first symptoms of insect transmission is drying and blackening of the male bud that start with the outer part of the leaf and eventually extend to the shaft. The fruits ripen unevenly and prematurely, turning from green to yellow and black rapidly. The pulp of the rotting fruits shows rusty brown stains.

Internal symptoms revealed by doing a cross section of an infected banana trunk are yellow-orange flashing of the tissues and the presence of yellow bacterial ooze which can also be seen from any other infected plant part.

Scientists therefore advise farmers to conduct pruning after three months when they identify those that are infected. They should cut infected suckers before it infests the top part where fruiting is supposed to occur.

Once it has fruited and formed fingers, remove the male bud and stop using tools like pangas, which are not disinfected. Once a farmer identifies a sucker that is wilting, it should be uprooted and destroyed.

Farmers in the Western part of the country have tried to manage the disease because they are following the above procedures but those in central Uganda sometimes apply chemicals, ash or pour urine on parts they have cut which does not work.