TUMAINI

Xanthomonas wilt of banana

Description - Note: If you want to confirm Xanthomonas wilt symptoms, please scan pseudostem to find yellow ooze in the stem. Also, scan cut fruit to find discoloured fruit pulp. Better known as BXW, and to a lesser extent as BBW (for banana bacterial wilt) - is a bacterial disease caused by the bacterium Xanthomonas campestris pv. musacearum (Xcm) that can easily spread from one mat to another,causing considerable yield losses.
Symptoms: The disease causes loss both through rotting of the fruit and death of the infected plant. The leaves gradually turn yellow and start looking lifeless as if they had been hanging above a fire. They eventually turn brown and die.  In flowering plants, the first symptoms of insect transmission are a drying rot and blackening of the male bud that starts with the outer bracts and eventually extend to the rachis. The fruits ripen unevenly and prematurely, turning from green to yellow and black rapidly. The pulp of the rotting fruits shows rusty brown stains.
Control: Unlike other pathogens, the bacteria causing BXW do not systematically invade all the stems in a mat. This means that the healthy-looking stems have a good chance of producing a healthy bunch, as long as the stems showing signs of the disease are removed and new infections are prevented. Cutting down at soil level when a plant shows signs of BXW and destroying the central meristem to prevent any regrowth of diseased plants will reduce disease transmission. However, periodical inspection of banana mats in your field, and acting quickly at the first signs of the disease, will reduce losses and keep the disease in check. For more information see http://www.promusa.org/Xanthomonas+wilt.

Fusarium wilt of banana

Description - Note: If you want to confirm fusarium wilt please do scan fake stem. Fusarium wilt or Panama disease is caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense  (Foc). Various types of Fusarium exist, and banana production systems have been affected since close to a century.
Symptoms: Fusarium wilt is a typical vascular wilt disease. The fungus invades the vascular tissue through the roots causing tissue discoloration and wilting, eventually killing the plant. The fruits do not exhibit any symptoms. Externally, the first signs of disease are usually wilting and yellowing of the older leaves around the margins. The yellow leaves may remain erect or collapse at the petiole. Sometimes, the leaves remain green, except for spots on the petiole, but still snap. The collapsed leaves hang down the pseudostem like a skirt. Eventually, all the leaves fall down and dry up.
Control: Neither fungicides nor fumigants can eradicate the fungus from the soil. Also the fungal spores can survive in the soil for decades. Drainage, environmental conditions, and soil type influence the host-pathogen interactions. Soils that suppress the disease have been reported in Central America, the Canary Islands, Australia, and South Africa. However, the underlying chemical, biological, and physical factors of this suppression are not well understood. The best solution is to replace all the susceptible cultivars with resistant ones, and to prevent disease spread. Like all other soil-dwelling Foc strains (Races 1 and 2), the TR4 type also cannot be controlled with fungicides and fumigants, and highly tolerant or resistant germplasm offers the best solution to maintain production. For more information see http://www.promusa.org/Fusarium+wilt .

Black Sigatoka

Description: Black Sigatoka or black leaf streak is a fungal leaf spot disease caused by the  Pseudocercospora fijiensis, formerly known as Mycosphaerella fijiensis. The disease does not immediately kill the banana plants, but if left unchecked, interferes with the photosynthetic capacity of the plant and thus significantly reduces fruit/bunch yields.
Symptoms: Most infections initiate on the underside of the leaf during the unfurling of the cigar leaf. The symptoms start as small specks that become streaks running parallel to the leaf veins. These streaks aggregate and eventually form spots that coalesce, form a chlorotic halo, and eventually merge to cause extensive necrosis. The first symptom, chlorotic specks, appears 14 to 20 days after infection. The time needed for symptoms to change to the necrotic phase depends on the type of cultivar, climatic conditions and severity of the infection.
Control: Preventive and curative practices are essential to control the fungal disease. The methods used to control BLS have been informed by the experience of controlling the disease in Latin America and the Caribbean. For more information see http://www.promusa.org/Black+leaf+streak

Bunchy top

Description: Bunchy top is a viral disease caused by the Banana bunchy top virus (BBTV). The disease, often called BBTD for banana bunchy top disease, gets its name from the bunchy appearance of infected plants. The virus is spread through infected planting material and by the banana aphid, Pentalonia nigronervosa, when it feeds on an infected plant and moves to healthy ones.
Symptoms: Bunchy top is named after one of the most characteristic symptoms of an advanced infection, when the leaves become progressively dwarfed, upright and bunched at the top of the plant, with wavy and chlorotic margins that tend to turn necrotic. The symptoms are most severe and distinctive when the infection arises from the virus moving from the parent plant to the physically attached suckers/lateral shoots. These plants are typically stunted (under 1 m) and rarely produce fruit.
Control: Regular inspections for the detection and destruction of infected plants, de-trashing (removal of dead/old leaves hanging down the plant), use of certified ‘virus-free’ planting materials, and opening new fields as far away as possible from existing plantations are essential. Another thing to remember about bunchy top is the management of ants, which tend the banana aphids. Ant colonies may be found in nests beneath dead leaves that cling to the pseudostem. Removal of these leaves will reduce nesting areas for the ants and subsequently aphid populations. Infected plants/mats cannot recover and will serve as a source of viral particles unless they are destroyed. For more information see http://www.promusa.org/Bunchy+top.

Eumusae leaf spot disease of banana (Pseudocercospora eumusae)

Description: Eumusae leaf spot (caused by the fungus Mycosphaerella eumusae) is one of three closely related fungi that cause a devastating leaf spot disease on banana. Symptoms are very similar to black Sigatoka (caused by M. fijiensis) and yellow Sigatoka (caused by M. musicola). All three pests can cause significant reductions in banana production.
Symptoms: Lesions first appear as small, linear, light-brown streaks which quickly lengthen and broaden, and become darker. Individual lesions mature into ellipsoid, sometimes ovoid, spots with light-brown to grey-white centres and dark-brown borders. When infection density is high, spots may coalesce at an early stage of development to form brown necrotic areas, the centres of the developing lesions turning light-grey. The leaf tissue yellows around these areas of necrosis. Lesions also develop on the midrib and eventually whole leaves can become necrotic. Young leaves are not affected.
Control: The fungicides which are used to control Sigatoka disease have also been used successfully to control Septoria leaf spot in Kerala, India; the disease is invariably mistaken for Sigatoka leaf spot. Prevent only using pest-free planting material. For more information see https://www.plantwise.org/KnowledgeBank/datasheet/40044 and https://www.dpi.nsw.gov.au/biosecurity/plant/insect-pests-and-plant-diseases/eumusae-leaf-spot.

Banana corm weevil

Description: The banana weevil (Cosmopolites sordidus) is one of the most serious pests of banana, plantain (Musa spp.) and Enset (Ensete spp). The weevil has contributed to the decline of highland cooking bananas in parts of East Africa. Weevil pest status in other groups of bananas is variable. In commercial Cavendish plantations the banana weevil has been reported to be relatively unimportant (Gold and Messiaen, 2000).
Symptoms: The infestation of the banana weevil begins at the base of the outermost leaf-sheath, stem and around the rhizome/corm. The damage is done when larvae tunnel deeply into the corm, causing corm damage which can lead to a reduction in plant vigour and possibly corm snapping at times of mild to severe wind impacts.Infested plants have dull yellow green and floppy foliage. Young infested suckers often wither and fail to develop.
Control: options include: 1. Manually kill weevils trapped using 2ft long split pieces of pseudostem placed face down near the stools and check after 1-2 days. 2. Uproot, chop and dry infected corms to kill eggs and larva.  3. Mulch (2ft away from the stem/mat), weed and apply manure in order to improve the plants’ tolerance to weevil attack.  4. Apply 50-100g neem seed powder around each stool at 4 months interval (higher rates can harm the plant) 5. Apply 1kg of neem leaf mulch per plant around the base of the plant.  6. Apply a 2L concoction of tithonia, mexican marigold, black jack, ash, and urine fermented for 14-21 days and diluted at a ratio of 1: 2, concoction: water.  For more information see http://www.promusa.org/Cosmopolites+sordidus.

Banana blood disease

Description: Banana Blood Disease is caused by a bacterium called Ralstonia syzygii subsp. celebesenis which belongs to a group of pathogens that cause bacterial wilts in banana. It is related to Moko disease.
Symptoms: The sequence of symptoms of Banana Blood Disease are influenced by the route and mode of infection. The gradual shrivelling and blackening of the male bud and fruits, on an otherwise healthy looking plant, indicates a ‘top-down’ infection by bacteria-carrying insects visiting the male bud or by people using contaminated tools to remove the male bud. Infected fruits also exhibit a reddish-brown discoloration when cut open. They eventually rot and dry out. Yellowing or flaccidity in older leaves, preceding the development of symptoms on the bunch and male bud or in plants that have not yet flowered, indicates a ‘bottom-up’ infection through wounds on leaves, pseudostem, roots or rhizome. These are generally caused by people using contaminated tools. The older leaves turn yellow, followed by wilting and necrosis. The wilted leaves then collapse, causing them to hang down around the pseudostem. Younger leaves turn bright yellow, before becoming necrotic and dry, and the emergence of the youngest leaf is arrested. If the plant has a bunch, the fruits may appear unaffected but exhibit a reddish-brown discoloration when cut open. The name ‘blood disease’ derives from the reddish discoloration of the tissues inside infected plants. This discoloration can extend from the male bud down to the rhizome, depending on the time since infection. The cross-section of an infected pseudostem or peduncle will secrete droplets of bacterial ooze, which may vary in colour from cream to reddish brown to black.
Control: options include: 1. Do not share planting materials. 2. Tool sterilisation.  3. Early de-budding to prevent insect-vectored transmission.  4. Uprooting of diseased mats.