Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria

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Infected plants are commonly observed after heavy rainfall periods in soils with poor drainage. Plants with distinct disease symptoms, clearly different from those produced by Fusarium or bacterial wilts, were observed during bacterial wilt surveys in ABB cooking banana fields in Papua New Guinea. Subsequent diagnostic studies revealed the presence of phytoplasmas related to the coconut lethal yellowing disease phytoplasma group. Wilting starts when pathogen densities increase throughout the plant, which prevents sufficient water from reaching the leaves due to vascular dysfunction Buddenhagen and Kelman, ; Denny et al.

The process by which colonization by bacterial wilts reduces water flow is not completely clear. There is no evidence for excessive transpiration linked to loss of stomatal control as could possibly result from a systemic toxin Buddenhagen and Kelman, ; Van Alfen, The primary factor is most likely plugging of pit membranes in the petioles and leaves by a high molecular mass extracellular polysaccharide Van Alfen, , but high bacterial cell densities, plant-produced tyloses and gums, and byproducts of plant cell wall degradation may be contributing factors Denny, A study by Minguez et al.

The Bugtok isolate was more aggressive than Moko, which showed poor invasion capacity. Although tylose formation was also found, results suggested that wilting was not only due to bacterial occlusion but also due to the destruction of cell walls of xylem vessels Minguez et al. Wilting may be observed on plants infected by R.

Typical Moko wilt symptoms appear once the pathogen has systemically colonized the pseudostem and underground rhizome. Infected dessert banana plants exhibit rapid yellowing and wilting of leaves and physically attached suckers, vascular discoloration in the pseudostem leafsheaths, premature fruit ripening or arrested fruit development and fruit blackening, and dry rot of fruit pulp Thwaites et al.

Bacterial ooze can be readily observed in internal tissues of any part of the plant that becomes exposed to the air. In certain conditions internal pseudostem discoloration caused by R. The inspection of bunches to observe rotting fruits, the presence of young distorted rotting suckers and bacterial oozing from exposed tissues is a common practice to discriminate between Moko disease Figure 4A and Fusarium wilt as rotting fruit and bacterial ooze do not appear in plants with Fusarium wilt.

Differences in inflorescence morphology across cultivars results in varying degrees of susceptibility to insect-mediated infection by bacterial wilts. Host-pathogen interaction and the importance of cultivar susceptibility and management practices on symptom development are illustrated by Bugtok in the Philippines and the B strain of Moko from Honduras. In the Philippines, Moko and Bugtok are two names describing different symptoms of the same disease caused by the same R. The symptoms are different because of a difference in epidemiology brought about by contrasting variety-cropping systems Molina, Moko is the term used for leaf wilting and yellowing symptoms observed in medium- to large-scale Cavendish plantations, while Bugtok describes fruit-rotting symptoms mainly observed in balbisiana cultivars i.

In commercial plantations of Cavendish dessert bananas in the Philippines, the Bugtok strains show similar symptom development to the Moko B strain from Honduras. In addition, fruit pulp becomes discolored grayish black to yellowish red and later becomes hard. There may also be a reddish brown discoloration of the vascular tissue of the pseudostem and peduncle, but rarely does this discoloration extend into the underground rhizome.

Bugtok is a result of inoculation by insects vectors through the male flowers, thus symptoms of rotting occur first in the fruits. Moko symptoms mainly occur when inoculation starts from the basal part of the plant, usually through contaminated tools used during pruning and de-suckering, a common practice in Cavendish cropping systems. Moreover, commercial Cavendish plantations practice early male flower removal and bagging of bunches with plastic bags to protect them from insect transmission Molina, Moreover, growers do not cover the fruits with plastic bags and early de-budding is rarely practiced.

In , an artificial inoculation experiment was carried out in Honduras using the Moko pathogen. Root-inoculated plants showed typical Moko symptoms i. This experiment showed that for the same pathogen, symptom development is linked to infection court.

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Symptoms of Xanthomonas wilt do not differ markedly from R. The incubation period for Xanthomonas wilt is about 3 weeks and, as for R. Visible Xanthomonas wilt symptoms after an insect-mediated infection on the male inflorescence part include wilting of male bud bracts, followed by drying of the rachis coupled with bacterial exudation, often followed by premature ripening of some or all of the fruits, and eventually wilting and death of the entire plant Ssekiwoko et al. An internal cross-section of a floral stalk shows yellow bacterial ooze from the vascular bundles, while a cross section of a fruit shows rusty brown stains in the fruit pulp Thwaites et al.


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Late floral symptoms when the banana bunch is physiologically mature have also been reported due to tool-mediated infections Ocimati et al. Xanthomonas wilt bacteria entering the corm, roots, pseudostem and leaves of banana plants, e. In addition, a yellow- or cream-colored ooze, typical of many bacterial infections, exudes within a couple of minutes of cutting tissue of an infected plant, and copious quantities of ooze may be produced over a period of several hours. A cross-section of a diseased pseudostem reveals brown or yellow streaks in the vascular tissue and yellowish bacterial ooze Tripathi, The affected pseudostems most often wilt and die.

Older leaves become yellow, followed by wilting, necrosis and collapse; younger leaves turn bright yellow before becoming necrotic and dry. The pathogen rapidly colonizes the entire plant, and suckers will also wilt and die Eden-Green and Seal, ; Eden-Green, b ; Supriadi, Pseudostem wet rot and rhizome rot caused by D. Pseudostem wet rot symptoms initially appear as translucid spots on sheaths in different parts of the pseudostem or in the base of leaves. Later they become reddish brown, to finally take a dark brown color and cover a large part of pseudostem.

The rot advances down in the pseudostem and toward the interior of leaf sheaths and stops when it reaches the bunch stalk.

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A fetid, amber-color liquid emerges when pressure is applied to affected tissues. Severely infected plants can develop young chlorotic leaves with necrotic margins and dwarf buds. Severely affected young plants do not flower Stover, ; Rivera, Plants developing from infected rhizomes show slow growing, chlorotic and flaccid leaves, as well as a rotting that spreads upward from the pseudostem base to the rest of the pseudostem Rivera and Ezavin, These plants may eventually collapse and die.

Weakened plants can fall down easily and break at soil level. Infected planting material develops weak buds and shoots that are often destroyed by the ascendant rot from the rhizome. In heavily infected fields, plant doubling i. Plants affected by Pectobacterium carotovorum show rotting with poor sprout emergence, dwarfing, yellowing and wilting of leaves, slow and retarded growth of plants and toppling over of mature plants and fruits Stover, The rhizome cortex shows soft humid brown to cream pockets that enlarge covering most of rhizome cortex.

Phytoplasma wilt external symptoms consist of yellowing and leaf death, meanwhile inside pseudostems, discontinuous streaking appears as small sections of black or brown vascular tissues, usually with wet and necrotic pockets Davis et al. Table 1 gives an overview of taxonomic classifications used to identify the major bacterial diseases affecting banana and enset, including the most recent genetic, geographic and ecotype diversity Eden-Green, ; Genin and Denny, Ralstonia solanacearum was first described and classified as Bacterium solanacearum by Erwin F.

Smith at the end of the 19th century Smith, The causal agent of bacterial wilt was then successively named P. The genus Ralstonia belongs to the family Burkholderia class Betaproteobacteria that includes nine genera and many human- and plant-pathogenic species and several symbionts.

Ralstonia is an aerobic, Gram-negative rod with a polar flagella tuft. It is oxidase positive, arginine dihydrolase negative, and accumulates poly-hydroxybutyrate intracellularly. Most strains denitrify and produce a diffusible brown-red pigment on rich medium. Ralstonia solanacearum is a heterogeneous species, as demonstrated by its large host range, pathogenic specialization and physiological and cultural properties, as well as its phylogeny Hayward, Despite being classified as a single species, it has been reported that different strains of R. Recently, Safni et al.

It is assumed that R. However, recent studies suggest that R. Traditionally, strains of R. Following this traditional classification system, the causal agent of Moko and Bugtok disease was recognized as R. Although useful, the biovar system lacks discriminating power due to its limited genetic basis Denny, A pathovar is a subspecific division that groups all bacterial strains that cause the same symptoms on the same plant host range Dye et al. The race-biovar system has now, in most cases, been replaced by the widely accepted phylotype-sequevar hierarchical classification scheme.

Phylotypes are defined as a monophyletic cluster of strains revealed by phylogenetic analysis of sequence data. Phylotypes are therefore major phylogenetic subdivisions within the R. More recently, Wicker et al. Using sequences of seven housekeeping genes gdhA, mutS, ppsA, adk, leuS, rplB, gyrB and two virulence-associated genes fliC and egl , eight clades comprising strains with distinct evolutionary patterns were identified Wicker et al.

The R. Phylotype IV hosts the two closely related bacteria R. Using a polyphasic taxonomic approach, Safni et al. The polyphyletic nature of the R. In recent literature it has been suggested that pathogenicity to banana lies in a very restricted number of genes or even allelic forms of the same genes that may be easily transferable through horizontal gene transfer Wicker et al. Although elegant, this assumption was not supported by recent comparative genomic work Ailloud et al.

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The robustness of the phylotype classification, thus far, would imply that it reflects true evolutionary lineages within the R. These lineages presumably developed when progenitors became geographically isolated and subsequently adapted to different environments and potential host plants Denny, The results support the effectiveness of the egl gene in revealing relationships among strains. Ralstonia syzygii subsp. Jones suggested that the blood disease pathogen coevolved with banana.

Buddenhagen however, indicated that this was unlikely due to differences in when and where the disease first appeared. Blood disease was first observed where wild bananas were not found Rijks, , supporting the suggestion that the bacterium originated on other plant species than banana Buddenhagen, Genetic analyses, by whole genome RFLP groupings, comparison of partial 16s ribosomal DNA sequences and analysis of tRNA consensus primer amplification products, indicate a close relationship, but distinctly different from other strains of the R.

Genetic analyses revealed that there is little diversity among strains of BDB Thwaites et al. Xanthomonas is a genus within the Gammaproteobacteria that includes species and hundreds of pathovars of Gram-negative, rod-shaped, plant-pathogenic bacteria Vauterin et al. The genus affects at least 44 plant families, including some economically important ones such as Solanaceae, Leguminosae , and Zingiberaceae Biruma et al.

The 26 other species were reduced to the pathovar-level and included in the type species X. The causal agent of Xanthomonas wilt of banana was originally described as X. Aritua et al. Therefore, Xcm was suggested but not yet formally accepted as a new pathovar of species X. Complete genome sequences have been reported for several members of Xanthomonas da Silva et al.

Although a genome sequence is available for X. These pathogenicity data suggest a host-jump by a strain of Xvh or Xvv onto a Musa species, because the Xcm strains retained pathogenicity to maize Aritua et al.


Wasukira et al. Their analysis revealed two major sub-lineages of the pathogen, suggesting that current outbreaks of Xanthomonas wilt on Musa species in the East African Great Lakes region may have had more than one introductory event, perhaps from Ethiopia Wasukira et al. In addition and based on comparisons of genome-wide sequence data from multiple isolates of Xcm and multiple strains of X.

Karamura et al. The six strains of X. Two and four strains of X. Bacteria associated with banana soft rots have been described as D. Dickeya paradisiaca belongs to Enterobacteriaceae class Gammaproteobacteria and is an aerobic, Gram negative rod, with peritrichous flagella, that appears single or in pairs that do not form spores. It is protopectinase, amylase, nitrate reductase, lecitinase and catalase positive; amylase, urease, oxidase, and gelatinase negative and produces gas from glucose.

Colonies in nutrient agar after 48 h are white to light gray, have irregular borders, fine granular growth, and after 4 days show a well-defined rising center. In King B media King et al. The pathogen can be selectively isolated with MNL culture media Hevesi et al.

Preventing and Managing Plant Diseases

Data on genetic diversity of D. In artificial inoculation studies, Rivera and Ezavin and Rivera et al. Isolates from necrotic rhizome can infect and cause lesions in rhizomes cortex and pseudostem tissues. However, isolates recovered from pseudostem wet rot lesions are only able to affect leaf sheaths, but not the rhizomes cortex.

Plants developing from infected rhizomes show slow growing, chlorotic and flaccid leaves, as well as a rotting that spreads upward from the base of the plant to the rest of the pseudostem Rivera and Ezavin, These plants may eventually collapse and die Figure 6. This organims has been mainly associated with head rot in banana. According to these authors, during and surveys, positive identifications of phytoplasmas belonging to 16SrII, 16SrVIII, groups, the BWAP as well as an undetermined phytoplasma were obtained from samples of plants having leaf death, internal pockets and discontinuous streaking but not from plants with leaf yellowing alone.

Phylogenetic analyses of the 16S rRNA gene showed that the phytoplasma from banana samples, clusters most closely with phytoplasmas associated with lethal yellowing type diseases of coconut in Papua New Guinea and other countries but do form a distinct lineage from all other phytoplasma groups. Epidemiological patterns are the result of many interacting factors, including populations of the causal organisms, host range, environmental conditions and management practices applied during disease outbreaks.

Yet, bacterial diseases affecting banana and enset share many communalities on epidemiology that consequently drive a common set of management options. Xanthomonas and Ralstonia spp. Such wounds may be either artificial or naturally appearing during plant development. The abscission of male flowers creates a moist site with open xylem vessels that can be inoculated by bees or other flying insects that carry the pathogen from diseased plants that are oozing bacteria on infected inflorescences Buddenhagen and Kelman, Management practices using garden tools such as machetes may also create entry sites for bacteria Ocimati et al.

In addition, nematodes may cause wounds enabling root entry for both Xanthomonas and R. Although Bugtok in the Philippines and Blood disease in Indonesia are caused by two different pathogens, R. These balbisiana-derived varieties have a wide opening of the bracts thus exposing the fresh male flowers, and thus attracting a large number of insects to the inflorescence.

It is a common observation that the male buds of this BBB variety attract more insects e. An analysis of sugar contents of male flower nectar indicated that cultivars with balbisiana genomes tend to be sweeter, with more simple sugars compared to the other varieties Dimyati et al. As a result, cultivars like Cavendish AAA and Lakatan AAA , are not seriously affected by Bugtok under small-scale farmer conditions because insects do not prefer to feed on these varieties Molina, More recent findings in Xanthomonas wilt affected zones revealed that though insect populations play an important role in disease spread, the observed high susceptibility of ABB or BBB cultvars is attributed to their non-persistent male and neutar flowers and bracts Addis et al.

Contaminated farm machinery, garden tools and machetes used for pruning and de-suckering, and infected fruit and rhizomes used as planting material are also effective vehicles of dissemination Ploetz et al. Contaminated water reservoirs for irrigation purposes are extremely effective to disseminate R. For instance, in Colombia, in spite of a rigid Moko control program, over 20, cases of Moko were recorded during in Cavendish plantations in Santa Marta. In Mexico, flooding and contaminated planting materials allowed the introduction of Moko to disease-free areas Fucikovsky and Santos, Currently there is no report or evidence of Xcm spread through soil or by water.

Soil-related dispersions play a significant role for Ralstonia and Dickeya , but it is of limited importance for Xcm bacteria Biruma et al. Infected soil, vehicles and tools move the blood disease pathogen within plantations and planting material and fruits are capable of spread at long distances Buddenhagen, In contrast, the survival period of Xcm bacteria is limited, ranging from 9 to 35 days in plant debris or soil Mwebaze et al.

Latently infected planting materials are known to promote long-distance dispersal of bacterial wilt pathogens Eden-Green, ; Molina, For example, the dispersion of Moko from Central America to the Philippines has been attributed to infected suckers Rillo, , ; Buddenhagen, In Indonesia, the movement of blood disease can also be traced with movements of planting materials and infected plant parts especially the balbisianas ABB and BBB since these are important cooking bananas and are used in socio-cultural events.

Nakato et al. Samples of banana fingers and rachis were collected from markets within Kampala, Uganda and at border points of Uganda with the Democratic Republic of Congo, Kenya, Tanzania and Rwanda. Hence, quarantine and prevented movement of plant parts from infected to clean areas is imperative. Strain-specific dispersion ability has not been studied for Xcm bacteria, although the two major sub-lineages identified by Wasukira et al. By contrast, different strains of R. For instance, B strains see the section on causal agents of bacterial wilt diseases are mainly soil-borne and transmitted by root-to-root contact and farm management practices such as pruning.

Insects may transmit B strains, but this is, however, rare, as plants infected by B strains exude relatively little bacterial ooze. Trigona bees, wasps, and other insects have been reported to disseminate the SFR and, to a lesser extent, B strains Stover, ; Buddenhagen, ; Jones, ; Ploetz et al. Generalist insects and stingless bees, such as Trigona spp.

On blood disease infected plants, bacteria-filled droplets begin to ooze from such cushions about 15—25 days after infection. Although insects frequent both male and female flowers, these fresh cushions are the only surfaces containing open xylem vessels and nectar-like sap. The infection court i. Dispersion by insects of the BDB R. Mairawita et al. In Sulawesi, various large wasps, Oncopsia spp. Insects were also seen feeding on fresh cushions. Tinzaara et al. A reduced level of insect vector transmission of Xanthomonas wilt has been reported in Ethiopia, in North Kivu, eastern DR Congo and Rwanda at altitudes above 1, m above sea level masl Addis et al.

It is postulated that the lower temperatures are not favorable for insect vectors. The occurrence of isolated cases of Xanthomonas wilt in remote places in various districts across Uganda far from the originally identified disease sites suggested the involvement of long distance vectors in the transmission. Buregyeya et al. The bacterium can survive up to 3 days on facial hairs of bats and up to 5 days on birds, making these animals potential long distance transmitters for the disease Buregyeya et al.

Since these animals mostly forage on male flowers, the early removal of male buds as is recommended to prevent insect vector transmission from bananas would limit disease spread. Agricultural practices such as the use of cableways to transport bunches and tools from the plantations to packinghouses may also be important for bacterial dispersion. Munar-Vivas et al.

Disease progression is largely dependent on host susceptibility, environmental factors, existence of contaminated water sources and management practices. Incubation periods may vary depending on the maturity of the infected plant, method of inoculation, route of infection, and environmental conditions. In the case of Xanthomonas wilt, higher incidence levels are often observed in the rainy season compared to the dry season Shimwela et al.

Caution must thus be taken when cutting diseased plants in the rainy season as higher inoculum levels may cause increased disease transmission rates when tool sterilization is not carried out. Dickeya paradisiaca infects the plants through open entries and wounds produced during sanitation of senescent leaves attacked by black Sigatoka and pruning of suckers Rivera, ; Thwaites et al. Severe epidemic outbreaks are commonly observed after long periods with water deficit during the hot dry seasons in Central America. These conditions associated to poor sanitations practices enable severe symptom development including plant toppling.

According Davis and Ruabete , all Papua New Guinea phytoplasma records so far known are from herbaceous dicotyledonous hosts. Based on PCR detection, cloning and sequencing, the BWAP was also found in banana plants from different places of Papua New Guinea with abundant coconuts and showing no signs of phytoplasma like disease. The apparent lack of phytoplasma transfer between host species were explained by so far unidentified differences between BWAP or because difference in feeding behavior of vectors present Davis et al. Further investigations into the phytoplasma disease status of monocotyledonous crops and weeds as well as studies to determine the insect vectors are essential to develop management strategies in banana and possibly coconut crops.

Integration of cultural practices with sensitive and specific diagnostic tools, transgenic approaches and conventional breeding may offer a more sustainable and environmentally friendly approach to control bacterial diseases. Here we describe control methods that are elementary for all bacterial diseases of Musa spp. Control methods that are currently still under development will also be discussed. In general, key factors for management success are systematic and disciplined adoption and execution of monitoring and eradication of infected plants.

A first critical step in plant disease management is diagnosis. Disease recognition in banana plants affected by bacteria is achieved by plant-by-plant inspection of the plantation at regular intervals. Although the appearance of infected plants may differ depending on the cultivar, mode of disease transmission, plant growth stage and environmental conditions, available data on the average incubation period suggest that inspections need to be done at weekly intervals Lehmann-Danzinger, The earliest appearance of Moko symptoms is 2 weeks after infection Lehmann-Danzinger, , while Xanthomonas wilt symptoms are typically evident within 2 weeks to 1 month depending on the entry point of the pathogen and age of the plants Ssekiwoko et al.

In regions, villages or farms where bacterial diseases are not present, the first line of defense is to avoid introducing them, i. Use of clean planting material and good sanitation procedures need to be always coupled to quarantine methods. The male inflorescence part is the primary infection site for insect vectors and no infection occurs when male buds are removed just after the formation of the last fruit hand, i. The practice of de-budding by means of a forked wooden stick just after the formation of the last hand is an effective control measure for all bacterial wilts of Musa spp.

A forked stick is used to avoid cross-infections associated with farm tools such as knives, machetes and sickles. In the Philippines, the effective management of Bugtok disease in commercial and backyard plantings of Saba BBB was demonstrated in extensive farmer field trials where early de-budding and fruit bagging with plastic bags were implemented Molina, Molina also showed that the sole application of early male bud removal was sufficient to effectively reduce Bugtok infections. In addition, Opina et al.

This practice is now advocated as a standard management practice in BBB Saba production systems. All the farmer field and out-scaling trials also provided empirical evidence that the inoculation route is generally through the male inflorescence part and not the female part , and that transmission is primarily by insects Molina, The results showed that early de-budding prevented insect vector transmission of the BDB in line with results obtained from de-budding trials carried out on Bugtok disease in the Philippines Soguilon et al.

Similar reports have been given for Xanthomonas wilt Blomme et al. Although de-budding is standard practice for commercial plantations e. Kagezi et al. Other cultural management strategies aimed at the reduction of insect vectors include bagging the inflorescence shortly after emergence with a polyethylene bag, muslin cloth, or a fine nylon mesh bag. Bags can be removed after all the fruits have set if followed by removal of the male inflorescence.

This bagging practice is common in commercial plantations in, e. It should be combined with mat and field sanitation, and removal of old, dead leaves. Injecting the male inflorescence with insecticide, as practiced by commercial plantation to control thrips, was not as effective against Bugtok disease as bagging Soguilon et al. A study by Nakato et al. Tool disinfection using a fire by holding the tool in the fire until the blade is too hot to touch is an alternative and has been advocated for Xcm elimination in east and central Africa. Buffer distances of over a mile without Bluggoe bananas can significantly reduce spread of Moko disease, although infrequently distances exceeding five miles have been bridged Buddenhagen and Elsasser, Roguing is an essential element of any disease control strategy.

However, in the case of bananas and plantains, the laborious nature of uprooting a mat and then disposing of the infected materials severely compromises the effectiveness of this technique. For example, it takes one person a full day to completely excavate two mats Mwangi, , redirecting resources away from other more lucrative activities.

Digging a pit to bury infected plant debris is cumbersome and burning the debris is perhaps even more demanding, considering the large amounts of fuel wood required. In Indonesia, however, farmers managed to effectively control banana blood disease by burning uprooted material Setyobudi and Hermanto, Biosecurity Australia summarized factors influencing R. In compost, the heat generated by micro—organism metabolism will kill the R.

Under wet conditions that favor saprophytes, the competition from a diverse microbial community growing in banana waste is likely to include members that produce lytic enzymes and antibiotic substances harmful to R. Taking these factors into consideration, the survival of R. Compared with the other major bacterial wilts affecting bananas and plantains, Xanthomonas wilt is almost uniquely a problem for small-scale farmers.

This elicits a need to tailor management options that are able to meet the specific constraints of resource-poor farming systems. Recent research findings indicate that Xcm bacteria do not colonize all lateral shoots i. This finding led to the use of a control method whereby only the visibly diseased plants within a mat are cut off at soil level. The underlying idea is that the continued removal of diseased plants in a field reduces the inoculum level and lowers disease incidence below the economic threshold. It is hoped that single diseased stem removal SDSR , together with the use of clean garden tools and de-budding will be effective and widely adopted by small-scale farmers affected by Xcm in East and Central Africa Blomme et al.

Whether SDSR would also be suited to control epidemics caused by other bacterial wilt pathogens is currently unclear and needs further investigation. Variable degrees of systemicity for R. The current control method for Moko in medium to large-scale plantations in Central and South America comprises the continuous and timely destruction using herbicides of all infected mats and those located in a 5—8 m buffer radius around infected mats, coupled to strict restrictions in access to the treated sites until no new cases are reported. Fallowing is particularly challenging for small-scale Musa farmers, as complete mat uprooting is labor intensive and complete removal of all corm pieces is often impossible, leading to subsequent shoot emergence.

Additionally, farmers should monitor for weeds that may promote survival of pathogenic strains of bacterial wilt.

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The number of years that a rotation crop must be grown depends on the level of infestation, rigorousness of corm uprooting, survival capacity of the pathogen in local soils, climate. At least a one-, but more often a 2- or 3-year rotation or fallowing is required to reduce Ralstonia population levels below the damage threshold Denny, On the other hand, fallow periods varying between 6 and 12 months depending on the intensity of management in the systems have been recommended following infestation by Xanthomonas wilt Turyagyenda et al.

Farmers are often challenged in adopting fallow or crop rotation practices due to constraints of land availability and pressures to produce either a subsistence crop or one with high cash value. This is particularly the case when the field has been affected by Moko, Bugtok or banana blood disease, due to the wider host range of Ralstonia bacteria Belalcazar et al. The efficiency of a fallow period is compromised by the ability of the pathogen to survive in the absence of the primary host crop, either in the soil or on plant species that persist during the fallow period.

Removal of alternative weed hosts is recommended Romo et al. Crop rotation has proven effective in reducing bacterial wilt populations. In Costa Rica, heavily infected banana plantations have successfully been rotated with velvet bean Mucuna pruriens for one or two cycles to reduce the R. Alternate hosts may act as reservoirs for infection, complicating the implementation of control strategies, such as fallowing or crop rotation Aritua et al. Ssekiwoko et al. For the medium to big commercial Cavendish plantations in the Philippines, plant to plant transmission of Moko disease mainly occurs through tools used in regular de-suckering and pruning activities.

Hence, infection commences from the basal parts or pseudostem. Insect transmission is rare since fruit bagging and early de-budding are standard plantation practices. In addition, it is very rare under commercial plantation conditions to find an inflorescence infection as early detection Moko scouting is done weekly and suspected un-shot infected plants are immediately eliminated, the infected mat quarantined and treated.

Early Moko scouting is mainly based on early symptoms of wilting and chlorosis on un-shot plants. There are hence as good as no sources of inoculum for insect transmission. Untill about 10 years ago, treatment of infected mats in large-scale plantations in the Philippines, consisted of chopping down aerial plant parts and treating the soil through an application of methyl-bromide. After its ban, the complete removal of infected mats was tested out through the injection of 2,4-D and glyphosate. However, this method was perceived as too cumbersome and especially too slow. The burning of rice hulls is now common practice.

This is followed by burning rice hull at two stages, i. Rice hulls burn slowly and totally inhibit the survival of bacteria. This method completely kills the remaining corms as well as the bacteria in the soil. In addition, pruning tool sterilization is carried out by using disinfectants as, e.

Moreover, small-scale farmers in the Philippines or Indonesia do not bag the fruits and they do not de-bud early enough if ever to prevent inoculation. This situation favors inflorescence infection. Movement of the bacteria from the fruit to the base of the plant is relatively slow for Bugtok disease. When incidence levels in Bugtok infected fields on small-scale balbisiana farms rise and tool transmissions occur although rare as tool use is uncommon , more and more leaf yellowing and wilting symptoms will be observed.

In commercial plantations, a strict and sustained preventive management approach is implemented, based on the capacity to quantify the risk in terms of economics the cost of control versus the cost of potential loss and an in-depth understanding of the epidemiology of the disease within the intensive mono-cropped production system. In contrast, in the case of small scale farmers, facing Bugtok or banana blood diseases, however, simple the control package might be de-budding and tool sterilization , adoption is not straightforward.

Many of the balbisiana cooking varieties are grown in small plantings in backyards, on unattended land or even as volunteer plantings. There will hence always be a good number of diseased plants left in the farming landscape that continuously provide sources of inoculum. In addition, a community approach to disease control most often does not work in small-scale farm setting. Similarly, poor adoption levels of tool sterilization have also been observed in Xanthomonas wilt infected regions of east Africa Shimwela et al. Soil amendments, such as organic matter e. Arenas et al. Under laboratory conditions, the application of potassium, nitrogen and calcium was identified as part of an integrated control package to reduce Xcm disease incidence and lengthen incubation periods Atim et al.

However, and in contrast, Ochola et al. For many years the usual method of Moko control was to dig out the infected mat and apply methyl bromide. The negative impact of methyl bromide on the ozone layer, however, led to the ban of this substance in many countries. The methodology is similar to that for methyl bromide, the main advantage being that dazomet does not leave any harmful residues in the soil Cronshaw, Formalin has reportedly been used to drench the soil around Ralstonia infected Cavendish banana plants in the Philippines, resulting in lower bacterial counts Pava et al.

A promising remedy for the control of Bugtok disease was the use of table salt, suggested by Jover, cited in Pava et al. Water was then poured into the hole to dissolve the salt. Field trials gave promising results. The technology package table salt at flowering in combination with bagging and de-budding and disease-free planting materials were transferred to farmers in 11 municipalities of Bukidnon Philippines during a 4-year project.

Chemical destruction using the injection of herbicides is an alternative that is fold less labor intensive than roguing Blomme et al. However, adoption by small-scale farmers affected by Xanthomonas wilt in east and central Africa has been minimal because herbicides are not always available in rural areas, the perceived high cost of herbicides, a reluctance to inject an already infected plant and reluctance to inject symptomatic plants, as physically attached asymptomatic plants might also die Blomme et al.

Herbicidal sprays have also been used in Central America in the fight against Moko disease Lehmann-Danzinger, In Belize, Moko disease was effectively eradicated following systematic surveys of ABB type Bluggoe mats and smallholder dessert banana cultivars, coupled with glyphosate treatment of all infected mats and all adjacent mats within a 5 m radius around infected mats Thwaites et al.

Biological control of Xcm through the use of antagonistic bacteria is still in an exploratory phase. Initial laboratory-based studies on banana in Uganda have shown promising levels of Xcm suppression by some bacterial isolates namely Burkholderia spp. Resistant cultivars represent an economical and environmentally benign disease control strategy Boshou, Unfortunately, sources of resistance to bacterial wilt are often polygenic, making it difficult or impossible to transfer all the identified quantitative trait loci into desirable cultivars, in part due to linkage with undesirable traits Boshou, Very little concerted effort has been made to develop Musa hybrids with such traits and extremely few cultivars or wild varieties have been found showing true resistance or tolerance Soguilon et al.

Bibliographic Information

None of a wide range of Musa cultivars 24 , including commercial AAA cultivars e. This observation was confirmed by Hermanto and Setyobodi in — in a field survey in Sumatra island Hermanto et al. These reports might indicate cultivar preferences of insect vectors, most likely linked to male flower nectar sweetness. In addition, Edison et al. They lack the male inflorescence or they have persistent male flowers and bracts preventing insect-mediated transmission.

In Sulawesi, a budless mutant of P. Efforts to propagate this mutant cultivar for widespread diffusion have thus far not been properly executed, despite good intentions and a brief collaboration with Chiquita in the early s Buddenhagen, Despite the selection pressures of banana blood disease on local cultivars, such budless mutants remain rare in Sulawesi Buddenhagen, The development of bacterial wilt-resistant plants through conventional breeding also suffers from the problems of long generation times, various levels of ploidy, sterility of most edible cultivars and limited genetic variability Tripathi et al.

However, following artificial inoculation of 31 diploid AA genotypes 21 natural germplasm and 10 hybrids with the Moko pathogen in a greenhouse in Brazil by De Oliveira e Silva et al. This demonstrates the occurrence of genetic variability among diploid AA banana genotypes in their ability to express resistance to R. Studies by Ssekiwoko et al. However, mechanisms of resistance toward Xcm in this wild banana still need to be elucidated.

In contrast, M. Both genes are defense genes which can intensify the hypersensitive response Lin et al. Xanthomonas wilt resistant transgenic banana lines over-expressing these hrap and pflp genes have been successfully generated using agrobacterium-mediated transfer techniques and embryogenic cell suspensions and were evaluated under laboratory, screenhouse and controlled field conditions Tripathi et al.

Transgenic lines that have proven resistant over three crop cycles in the field have been identified Tripathi et al. Bacterial diseases of banana continue to cause major losses in banana and plantain worldwide. These activities, when area wide performed in a systematic way and based on epidemiological parameters, may guarantee sustainable control. However, the current situations in Africa for Xanthomonas wilt , Latin America and the Caribbean for Moko and Dickeya suggest that more efforts are needed at different levels. Growers, technicians and extension workers should be trained on disease recognition, epidemiology and management practices, with the support of plant protection experts.

In the current molecular era, it is promising that an integration of sensitive and specific diagnostic tools together with transgenic approaches, conventional breeding and screening for escape cultivars may offer environmentally friendly and less labor intensive options to control bacterial diseases. All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Abayneh, T. Addis Ababa University, George. Abele, S. Food security in Rwanda. Addis, T. Bacterial wilt Xanthomonas campestris pv. InfoMusa 13, 44— PubMed Abstract Google Scholar. Garden tool transmission of Xanthomonas campestris pv.

Acta Hort. Ailloud, F. Comparative genomic analysis of Ralstonia solanacearum reveals candidate genes for host specificity. BMC Genomics Albuquerque, G. Moko disease causing strains of Ralstonia solanacearum from Brazil extend known diversity in paraphyletic phylotype II. Phytopathology , — Alvarez, A. Allen, P. Prior, and A. Hayward St. Google Scholar. Anonymous Arenas, A. PubMed Abstract. Aritua, V.

Characterization of the Xanthomonas sp. Plant Pathol. Atim, M. High potassium, calcium and nitrogen application reduce susceptibility to banana Xanthomonas wilt caused by Xanthomonas campestris pv. Plant Dis. Baharuddin, B. Pathological, biochemical and serological characterization of the blood disease bacterium affecting banana and plantain Musa spp. Verlag Gottin. Production of monospecific antiserum against the blood disease bacterium affecting banana and plantain. Phytopathology 84, — Belalcazar, S. September October 1 , eds M. Orozco-Santos, J. Orozco-Romero, M.

Robles-Gonzalez, J. Velazquez-Monreal, V. Medina-Urrutia, and J. Hernandez-Bautista Oaxaca: Artturi , 16— Biosecurity Australia Canberra: Biosecurity Australia. Biruma, M. Banana Xanthomonas wilt : a review of the disease, management strategies and future research directions. Blomme, G. Fine-tuning banana Xanthomonas wilt control options over the past decade in East and Central Africa. On-farm assessment of banana bacterial wilt control options.

Crop Sci. The effectiveness of different herbicides in the destruction of banana Xanthomonas wilt infected plants. Special Issue. Boshou, L. Buddenhagen, I. Bacterial wilt of bananas: history and known distribution. Trinidad 38, — ACIAR proceedings no. Ploetz, G. Zentmyer, W. Nishijima, K. Rohrbach, and H. Ohr St. Blood bacterial wilt of banana: history, field biology and solution. An insect-spread bacterial wilt epiphytic of Bluggoe banana. Nature , — Biological and physiological aspects of bacterial wilt caused by Pseudomonas solanacearum.

Designation of races in Pseudomonas solanacearum. Phytopathology Buregyeya, H. Role of birds and bats in long distance transmission of banana bacterial wilt in Uganda. Evaluation of distant transmission of banana bacterial wilt in Uganda. CAB International Invasive Species Compendium. Ralstonia solanacearum Race 2. Carter, B. Identification of Xanthomonas vasicola formerly X. Castellani, E. Coloniale Firenze 33, — Chen, C. The cloning and characterization of a hypersensitive response assisting protein that may be associated with the harpin- mediated hypersensitive response. New Releases.

It continues a series originated during a visit of prof. Both editors aim at a series of five volumes embracing, in a multi-disciplinary approach, advances and achievements in the practice of crop protection, for a wide range of plant parasites and pathogens. Two volumes of the series were already produced, dedicated to general concepts in IPM and to management and biocontrol of nematodes of grain crops and vegetables. This Volume deals, in particular, with diseases due to bacteria, phytoplasma and fungi.

Every day, in any agroecosystem, farmers face problems related to plant diseases. Since the beginning of agriculture, indeed, and probably for a long time in the future, farmers will continue to do so. Every year, plant diseases cause severe losses in the global production of food and other agricultural commodities, worldwide. Plant diseases are not limited to episodic events occurring in single farms or crops, and should not be regarded as single independent cases, affecting only farms on a local scale. The impact of plant disease epidemics on food shortage ignited, in the last two centuries, deep cultural, social and demographic changes, affecting million human beings, through i.

Product details Format Hardback pages Dimensions x x Illustrations note XXV, p. Other books in this series. Add to basket. Back cover copy The third volume of the series covers, in three Sections, emerging issues in the integrated management of main diseases of perennial and annual crops. The chapters provide basic data about the diseases concerned, in order to facilitate their detection and recognition either by field and laboratory inspection, discussing the main management possibilities experienced by farmers, plant pathologists and consultants, in different areas of the world.

Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria
Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria
Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria
Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria
Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria
Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria
Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria
Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria
Integrated Management of Diseases Caused by Fungi, Phytoplasma and Bacteria

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