Banana Bacterial wilt (BBW) was first reported in 2005 in Southwestern Uganda, the region that produces more than 60% of Uganda’s bananas annually (Kalyebara et al., 2006). BBW prevalence was kept below 5% between 2005 and 2008 (Kubiriba et al 2012).  This was due to combined use of farmer field schools and Integrated Agricultural Research for development (IAR4D) using cultural practices focusing on the communities supported by the subcounty and district action plans.   In 2010, BBW prevalence in the region increased to 34% due to incomplete and distorted information reaching the farmers; inadequate systems for surveillance of the disease and inadequate mobilization of stakeholders to control the disease.   In 2012, the strategy for BBW control changed to formulating BBW control action plans focusing on the region (10 districts of the Ankole region) rather than the community (100-300 farmers) by a mix of stakeholders from the region (farmers, political leaders, extension officers and administrators). Then the action plans of districts and subcounties were designed to achieve the goal of the regional action plan, rather than to support community action plans. The overall implementation of the regional plan was spearheaded and coordinated by the regional taskforce, instituted by regional stakeholders.  In August, 2012, 93.4% of the farmers in selected hotspots had over 20 infected plants in their fields. By June 2013, BBW had been controlled in over 90% and over 70% of the previously affected fields in 6 and 3 hotspots respectively. 

Mycosphaerella eumusae has similar leaf spot characteristics to M. fijiensis and M. musicola.

Primary lesions are brown streaks that expand to form large brown spots.

This stage of the disease is the most recognisable and can be used to distinguish between the three Mycosphaerella leaf spot diseases.

As the disease progresses, spots become grey in the centre but keep a brown border

Leaf spots amphigenous, initially visible as faint brown streaks, developing into oval or elliptical light brown lesions with grey centres and dark brown borders, coalescing to form large, brown necrotic areas under favourable conditions.

Grey spots and patches are visible in necrotic areas, and lesions are surrounded by a chlorotic yellow zone. Pseudothecia amphigenous, predominantly hypophyllous, black, subepidermal, becoming slightly erumpent, globose, up to 80 µm diam., apical ostiole 10–15 µm wide; wall consisting of 2–3 layers of medium brown textura angularis.

straight, obovoid with obtuse ends, widest in the middle of apical cell, medianly 1-spetate or basal cell slightly longer than apical cell, tapering towards both ends, but with more prominent taper towards lower end.

 

Typically yellowing and wilting of older leaves, as well as reduced fruit size and eventual rotting of the fruit.

In addition flowers can become blackened and shriveled, and the vascular tissue discolored. Exclusion of the disease where it is not present is the only effective means of control.

If an area does become infected all of the infected plants must be eliminated, which is why strong sanitation practices must be used to reduce the spread of disease.

The overall symptom picture of the disorder observed during disease surveys   consist  mainly in poor development, rapid withering of older leaves, reduced number of functional leaves at bearing stage, poor bunch emergence, incomplete fruit filling, and premature ripening of fruits.

In addition to the above symptoms, other characteristics observed  are as follows:


Accelerated drying of leaves, starting from the oldest leaves, and progressing towards the heart (unfurled) leaf was noted in all cases.

Leaf necrosis usually started from the apex of a leaf and progressed towards the base thus killing the entire tissue. Leaf spotting on other parts of the leaf blade was also noted, though this type of infection was less common.

Dark brown to reddish brown necrotic streaks developed along the leaf veins on young leaves which became visible to the naked eye when
they reached about 1mm.

With progression of the disease,these streaks developed into dark spindle- shaped lesions 10-20 mm long , often surrounded by a yellow halo. Lesions coalesced under climatic conditions favorable to disease development and killed the entire leaf tissue rapidly.

The centers of all lesions turned whitish in colour. In the superhumid zone affected plants often had less than four functional leaves which ultimately lead to emergence of small distorted bunches and prematurely ripening fruits.

Control;

High humidity favours development of the disease complex and can be controlled by modification of
the canopy environment through the following:

The recommended planting density of 2000 plants per hectare with spacing of 2.5 m x 2 m should not
be exceeded as this allows sun rays to reach the soil within the plantation.

Maintaining sucker density at a low level (2 - 3 suckers per plant). This allows good ventilation
within the plantations enabling the banana plant to thrive better in a well aerated environment.

Ensuring a good drainage system, and effecting regular weed control. A dense weed population
increases the humidity through transpiration.

The aim is to reduce the level of inoculum potential through:

(i) Removal of plants under stress (e.g. stunted plants or plants infested by banana weevils)

(ii) Removal and destruction of hanging leaves (infected or dried up)

(iii) Cutting down bearing plants which are severely affected.



This is transmitted by several aphid species and may occur inone form or the other where bananas are grown.

The diseaseis rare and may not be serious.

The most characteristic symptom is the loss of leaf colour in pathes, rendering leaves variegated in appearance. The
variegations may be roughly parallel to the lateral veins, but not always, giving leaves a striped appearance. As the disease

progresses, leaves emerge, having perhaps one or both sides of the lamina not fully developed so that the leaf margin instead
of being smoothly curved is irregularly wavy, often with blotches of necrotic tissue and the lamina is reduced in width.

Sometimes rotten areas are found throughout the leaf sheaths and the pseudostem.

In cooler areas, rotting of the heart leaf may develop to such an extent that a soft black rot extends right down to the corm
(the 'heart rot' condition). The older leaves show black or purple streaks and may shed.

Fruits on infected plants may not show any symptoms or maybe stunted with chlorotic streaks or may show necrosis

Planting matem1 should be checked so as not to introduce the disease to a new plantation. Plants of the tomato and cucumber
families, maize, Panicum sp. and Digitalia sp. are known tocarry the virus. Intercropping bananas with such plants should be avoided. Non-host cover crops can be planted to suppress:
weeds.

The infected plants must be destroyed by digging them up Eradicate all the suckers in the mat even if they appear healthy
Where possible the-vegetation surrounding the diseased site can be destroyed to kill aphids using malathion or another suitable
spray.

The vast majority of the bananas currently grown and consumed were not conventionally bred but are selections made over probably thousands of years from naturally occurring hybrids. Cultivated bananas are very nearly sterile and as a consequence are not propagated from seed but rather through vegetative propagation, primarily suckers as well as more recently micropropagated or tissue cultured bananas. These factors, very old selections, near sterility and vegetative propagation, mean that these bananas have not been genetically improved either for resistance or improved quality and are becoming increasing in affected by serious pests and diseases.

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