Beware of fruit peel and other diseases 

Banana is a common cash and food crop grown by most farmers in Uganda comprising various types and varieties.

A number of farmers are engaged in growing the East African Highland banana commonly known as Matooke while others grow the sweet bananas such as Cavendish and apple banana.

Majority of the farmers engaged in growing Matooke are based in western region especially in the districts of Isingiro, Ntungamo, Mbarara and Bushenyi, among others.

Diseases

Mr Wilson Kakuru, an agriculturalist and the extension service worker based in Ntugamo District, explains that farmers in this location do experience challenges of banana diseases and pests but on the other hand with guidance from his team and scientists breeding banana, the farmers do follow best agronomy practices.

This has led them to have reasonable harvests compared to other regions say in central Uganda where the diseases are prevalent.

Fruit peel

Fruit peel is usually acute during dry spells. They are caused by pests called rust thrips which attack by feeding on the green surface on the banana fingers. The attacked fingers turn brown and then black. The discoloration is on the surface of the fruit peel. In extreme cases of severity, the whole bunch will appear blemished.

It sometimes leads to the fingers not growing normally and in most cases consumers shy away from purchasing it.

According to Kakuru, farmers have been experiencing it but it became acute two years ago and upon reporting to scientists and his team, they have been advising farmers to spray affected bunches with chemicals such as ridomil and rocket to phase off the insects. However farmers are advised to harvest a bunch after 14 days from spraying.

Farmer experience

Mr Barnabas Arinaitwe is a farmer from Rubare Town Council growing the East African highland banana on a four-acre land and he has done this for the last three years.  He narrates that had it not been for the good agronomy practice, the fruit peel was becoming a menace on his farm as well as other farmers.

When he first spotted it, he would cut the entire bunch but seeking advice from the extension workers, he is now following the right agronomy as well as spraying with the recommended chemicals.

Other diseases

Fusarium wilt is another disease which is prevalent on banana cultivars that are used primarily as dessert bananas and for brewing, such as Kayinja.

The available literature indicates that similar symptoms were observed by scientists in 1993 on the indigenous and dominant highland cooking bananas in western Uganda but later confirmed on other varieties across the country.

Banana Bacterial Wilt also known as Xanthomonas wilt (BXW) is a disease that causes a banana plant to rot from the inside out. The disease is triggered by the bacteria Xanthomonas vasicola pv. Musacearum. It causes leaves to appear dull green, wilt during the day and recover at night and eventually yellow and brown at the margins leading leaves to wither before the plant dying off.

Black sigatoka is another disease that has attacked several plantations. It is a fungal disease that destroys banana leaves leading to blackening thereby reducing the number and size of fruit. It is very severe on Cavendish banana variety, ladyfingers and the East African Highland banana and apple bananas.

These are managed by removing affected plants and burning them. Farmers are advised to remove the flower shooting part because it attracts insects which usually end up transmitting the disease.

Banana weevil

It results from larvae feeding and tunnelling into banana corms and pseudo stems. The adult weevil lays its eggs near the corm and on hatching, the larva attacks the underground part boring tunnels in it.

As the weevil larvae grow in size, they make large tunnels about 115 cm in diameter and may extend 60 to 100 cm up the pseudo stem.

The damage weakens the plant and interferes with uptake of nutrients and water and weevil infestation of young plants causes stunting, disruption and delay of fruiting and sometimes leads to plant death.

Heavily infested plants produce small bunches and have reduced resistance to drought and strong winds, leading to snapping and toppling of large or matured flowered plants.

Nematodes

Nematodes are tiny worms which live in the soil and infest plant roots. During their process of feeding, nematodes tunnel through the root cortex leading to expansion of the lesions around.

The lesions collapse into large necrotic patches reddish purple in colour, a symptom known as root necrosis. It results in premature root death or root fracture at points where necrosis girdles across.

This necrosis interferes with the water and nutrient exchange passage and the most obvious symptom of nematode damage is the toppling over of the entire plant, particularly in fruiting ones. In general, damage to the banana root system results in stunted growth, premature leaf drop, reduced vigour, and delayed ratooning and increased susceptibility to water deficiency.

Control measures

There are cultural measures for the pests which include manipulation of weevil habitat and oviposition site to provide line of defense against the banana weevils.

Others are use of clean planting materials to minimise the spread of the weevils and disease spread which are mainly carried to new sites with infested suckers.

Good husbandry which involves clean weeding, de-suckering, pruning, manuring and mulching which produce vigorous plants that are more tolerant to weevil damage as well as destruction of post-harvest residues.

Removal and splitting of harvesting stems into small strips and spreading them out to dry quickly reduces hiding and breeding sites for the weevil. It also exposes weevil eggs and larvae to desiccation.

Trapping which are of are of two types including pseudo stem and disc-on-stump. Pseudo stem trap is made from pseudo stem pieces split longitudinally into halves and placed a banana plant with split surface on the ground.

Weevil

It results from larvae feeding and tunnelling into banana corms and pseudo stems. The adult weevil lays its eggs near the corm and on hatching, the larva attacks the underground part boring tunnels in it.

As the weevil larvae grow in size, they make large tunnels about 115 cm in diameter and may extend 60 to 100 cm up the pseudo stem.

The damage weakens the plant and interferes with uptake of nutrients and water and weevil infestation of young plants causes stunting, disruption and delay of fruiting and sometimes leads to plant death.

Heavily infested plants produce small bunches and have reduced resistance to drought.