Stem-end Rot Of Mango Research Articles

First report of a Neofusicoccum sp. causing stem-end rot of mango

In November 2013, a Japanese fruit importer noted a large, black, water-soaked lesion at the stem end of a mango from the Philippines. A fungus was isolated from the lesion and identified as a Neofusicoccum sp. closely related to Neofusicoccum sp. karanda, based on morphological and phylogenetic analyses. The isolated fungus caused black, water-soaked lesions on mango after back-inoculation. The symptoms were also very similar to those caused by Lasiodiplodia theobromae, which causes stem-end rot on mangos in Japan. Therefore, we propose the addition of Neofusicoccum sp. closely related to Neofusicoccum sp. karanda as a cause of stem-end rot on mango.

Partial characterization of toxins associated with stem end rot of mango caused by Lasiodiplodia theobromae

In this study, the toxicity of liquid culture media from different isolates of Lasiodiplodia theobromae was characterized and some properties of the toxic metabolites were distinguished. In this work toxin producing ability of L. theobromae was revealed by studying the physical parameters viz., osmotic potential, toxin concentration, pH, temperature and biological parameter like host specificity and wilting index. The obtained results showed that the optimal toxin-production conditions for L. theobromae in potato dextrose broth under pH 6.0, at 25-35°C for 7 days. The liquid culture from all isolates were toxic to mango plants and induced the rapid wilting. The toxin obtained from the liquid culture has thermal, acid base stability and a broad range of toxicity to main host and non-host plants. Moreover, the direct bioassay for two components of the liquid filtrates precipitated by ethanol showed that the active ingredient of the toxin is a kind of non protein substance, which was further endorsed by the papain hydrolysis analysis. Our results confirmed the chemical nature of toxic compound elucidating the favorable environmental conditions for toxin production of L. theobromae and proved potential role of toxic metabolites in the mechanism of disease development.

Immunoassay‐based Techniques for Early and Specific Detection of Latent Postharvest Anthracnose in Mango

AbstractThe postharvest anthracnose pathogen Colletotrichum gloeosporioides inciting latent or quiescent infection of mango was detected in early stages using immunoassay methods. Twenty‐five pathotypes isolated from different agroclimatic zones of Tamil Nadu, Karnataka and Pondicherry, India, revealed the variation in protein profile analysis (SDS‐PAGE). The polyclonal antibodies (PCA) were raised against the unfractioned mycelial protein (UMP) and a 40‐kDa polypeptide present in all pathotypes. Standardization of antigen and antiserum dilutions revealed that an antigen dilution of 1 : 200 (protein concentration of 20 μg/ml) and antiserum dilution of 1 : 100 (protein concentration of 40 μg/ml raised against UMP) and 1 : 200 (protein concentration of 20 μg/ml raised against 40 kDa polypeptide) was found to be optimum for the detection of anthracnose pathogen. Both antisera detected the C. gloeosporioides antigen in enzyme‐linked immunosorbent assays (ELISAs), dot immunobinding assays (DIBAs) and Western blots. The specificity in reaction was compared by isolating other Colletotrichum spp. from various hosts viz., C. lindemuthianum (beans), C. falcatum (sugarcane), C. musae (banana), C. capsici (chillies) and Botryodiplodia theobromae (mango). The antisera generated against UMP revealed the cross‐reaction with other host isolates and mango stem end rot pathogen (B. theobromae). The PCA raised against 40‐kDa polypeptide exhibited the specific reaction with C. gloeosporioides isolates in all the immunoassay techniques. By utilizing both PCA, the presence of latent infection was observed in healthy‐looking leaves, flowers and fruits in orchard conditions. The fruit tissues recorded high absorbance values followed by flowers and leaves in all the detection methods. The ELISA technique was also useful in assessing the pathogen inoculum at various biocontrol formulations sprayed mango trees under field conditions. The fluorescent pseudomonad strains mixture (KFP1 + FP7) amended with chitin sprayed at 30‐day intervals revealed the significant reduction in pathogen load than other formulations and unsprayed control.

果梗部熱処理法によるマンゴー軸腐病の防除

果梗部熱処理法によるマンゴー軸腐病の防除

Botryosphaeria, Neofusicoccum, Neoscytalidium and Pseudofusicoccum species associated with mango in Brazil

Members of the Botryosphaeriaceae are well known fungi associated with dieback, canker and fruit rot on various hosts worldwide, including mango. The aim of this study was identify a large collection of Botryosphaeriaceae species associated with dieback and stem-end rot of mango in the semi-arid region of Northeastern Brazil, and compare the species in relation to mycelial growth, pathogenicity and virulence. A total of 115 isolates were sampled and based on morphology and DNA sequence data (ITS and EF1-α) seven taxa were identified, namely, Botryosphaeria dothidea, B. mamane, Fusicoccum fabicercianum, Neofusicoccum parvum, N. brasiliense sp. nov, Neoscytalidium dimidiatum and Pseudofusicoccum stromaticum. B. dothidea and P. stromaticum were the most commonly isolated species, which represented 37 % and 33 % of all isolates respectively. B. mamane is reported for the first time in association with mango diseases worldwide. There were significant differences among the species obtained in this study in relation to optimum temperature for mycelial growth and mycelial growth rates. All species were pathogenic on mango fruit. There were significant differences in virulence among the species, with Ne. dimidiatum and N. parvum being the most virulent species, while P. stromaticum was the least virulent.

Species of Lasiodiplodia associated with mango in Brazil

Mango (Mangifera indica) is a major tropical fruit species cultivated in Brazil. The objective of this study was to identify species of Lasiodiplodia associated with dieback and stem-end rot of mango in the semi-arid region of Northeastern Brazil, and compare the species in relation to mycelial growth, pathogenicity and virulence. A total of 120 isolates of Lasiodiplodia were used and identifications were made using a combination of morphology and phylogenetic analysis based on partial translation elongation factor 1-α sequence (EF1-α) and internal transcribed spacers (ITS). The following species were identified: Lasiodiplodia crassispora, L. egyptiacae, L. hormozganensis, L. iraniensis, L. pseudotheobromae, L. theobromae and Lasiodiplodia sp.. Lasiodiplodia theobromae was the most frequently isolated species, which represented 41 % of all the isolates. Only this species had been previously reported on mango in Brazil, while the other species represent the first report associated with mango tree diseases in this country. Lasiodiplodia crassispora is reported for the first time associated with mango diseases worldwide. There were significant differences in mycelial growth rates among the Lasiodiplodia species and also in the optimum temperature for growth. All species of Lasiodiplodia were pathogenic on mango fruit. There were significant differences in virulence among the species, wherein L. hormozganensis and Lasiodiplodia sp.were the most virulent, while the least virulent were L. iraniensis, L. pseudotheobromae, L. crassispora and L. egyptiacae.

A nested multiplex PCR for species-specific identification and detection of Botryosphaeriaceae species on mango

Lasiodiplodia theobromae (Pat.) Griff. & Maubl, Neofusicoccum parvum Pennycook & Samuels, N. mangiferae Syd. & P. Syd., and Fusicoccum aesculi Corda, all anamorphs of Botryosphaeriaceae species, are the causal agents of mango stem-end rot and fruit rot in Taiwan. Identification of these fungal species based on morphology has not been easy due to their extensive plasticity for some of the morphological characters. To aid reliable identification of Botryosphaeriaceae species associated with mango fruits, four pairs of species-specific primers were designed according to sequences of the ribosomal internal transcribed spacers (ITS), and a rapid method was established based on nested multiplex polymerase chain reaction (PCR) in this study. To perform the analysis, PCR was first run with ITS1 and ITS4 as the primers, followed by a second PCR with the addition of all four sets of species-specific primers. With this method, a low limit of 100 fg-1 pg of purified fungal DNA was detectable. It could also successfully detect L. theobromae, N. parvum, N. mangiferae and F. aesculi in total DNA extracted from inoculated mango fruits. This assay provides a rapid and sensitive method for the identification of Botryosphaeriaceae species and diagnosis of mango fruit rot and stem-end rot as well.

First Report of Stem-End Rot of Mango Caused by Phomopsis mangiferae in Taiwan.

Mango (Mangifera indica L.) is grown on approximately 20,000 ha in Taiwan. It is an economically important crop and the income of many fruit farmers comes primarily from mango production. During 2006 and 2007, a stem-end rot disease was observed 1 week after harvest on 28 to 36% of stored mangoes picked from six orchards in the Pingtung, Tainan, and Kaoshiung regions. Two popular mango cultivars, Keitt and Irwin, showed greater susceptibility to this disease, while 'Haden' was found to be moderately susceptible. In storage, symptoms initially appeared as light-to-dark brown lesions surrounding peduncles. Rot symptoms advanced slowly but eventually penetrated the mesocarp, which consequently reduced the commercial value of fruits. The fungus formed abundant pycnidia (0.1 to 0.6 mm in diameter) on infected fruits in advanced stages of symptom development. Pieces of symptomatic fruits plated on acidified potato dextrose agar (PDA) and incubated at 25 ± 1°C consistently yielded the same fungus. A single conidial isolate was cultured. Pycnidia developed on PDA after continuous exposure to light for 9 to 14 days. On the basis of morphological characteristics, the fungus was identified as Phomopsis mangiferae L. (2,3). Pycnidia released two types of conidia: α-conidia (5 to 10 × 2.3 to 4.0 μm) were hyaline and oval to fusoid; and β-conidia (15.0 to 37.5 × 1.3 to 2.5 μm) were hyaline and filiform with characteristic curves. Conidiophores were hyaline, filiform, simple or branched, septate, and 15 to 75 μm long. Cultures incubated under continuous fluorescent light (185 ± 35 μE·m-2·s-1) at 25°C for 3 days were used as inoculum for pathogenicity tests. Five fruits from 'Keitt' were wounded with a sterilized scalpel and each wound (2 × 2 × 2 mm) was inoculated with either a 5-mm mycelium agar plug or a 0.5-ml spore suspension (105 conidia per ml) of the fungus. Five wounded fruits inoculated with 5-mm PDA plugs or sterile water alone served as controls. Inoculated areas were covered with moist, sterile cotton. Fruits were enclosed in plastic bags and incubated at 24°C for 3 days. The test was performed three times. The same symptoms were observed on all inoculated fruits, whereas no decay was observed on control fruits. Reisolations from the inoculated fruits consistently yielded P. mangiferae, thus fulfilling Koch's postulates. This disease has previously been reported in Australia, Brazil, China, Cuba, India, Malaysia, and the United States (1). To our knowledge, this is the first report of P. mangiferae causing stem-end rot disease on mangoes in Taiwan. Our report necessitates taking preventive strategies in the field, prior to or after harvest, to contain postharvest losses in mangoes.

Effectiveness and molecular characterization of Burkholderia spinosa, a prospective biocontrol agent for controlling postharvest diseases of banana

Prospective antagonists for controlling Colletotrichum musae were isolated from the fructosphere of a range of dessert and cooking type banana varieties grown in Sri Lanka. Out of the isolated microorganisms, 44 bacterial and 31 fungal isolates showed more than 50% C. musae colony growth inhibition in vitro. Among 32 bacterial isolates which showed inhibition zones against C. musae under in vitro conditions, four isolates were highly effective in controlling banana anthracnose, crown rot and blossom end rot in vivo when artificially infected banana (variety Kolikuttu) were dipped in an antagonist suspension (10 8 cfu/ml) containing Tween 20 (0.02% v/v) for 5 min. Of these four, Burkholderia spinosa was used for further studies as a prospective biocontrol agent/biopesiticide. A suspension of B. spinosa (10 5 cfu/ml) containing Tween 20 (0.02% v/v) was effective in controlling anthracnose and blossom end rot of a range of dessert banana varieties (87–95% and 81–82% disease reductions, respectively), while a concentration of 10 4 cfu/ml with Tween 20 (0.02% v/v) was sufficient to have a 86–98% control of crown rot. B. spinosa showed 45–73% colony growth inhibition of C. gloeosporioides, Botryodiplodia theobromae and Thielaviopsis paradoxa isolates causing anthracnose and stem end rot of avocado, mango and pineapple in vitro. Significant in vivo control of these diseases in avocado, mango and pineapple was also achieved with antagonist concentrations ranging from 10 4 to 10 6 cfu/ml (28% reduction of mango anthracnose by 10 5 cfu/ml, 38% reduction of avocado anthracnose by 10 4 cfu/ml, 17.5% reduction of mango stem end rot by 10 5 cfu/ml, 14% reduction of avocado stem end rot by 10 6 cfu/ml and 34% reduction of pineapple stem end rot by 10 5 cfu/ml). Molecular analysis of recA gene by PCR-RFLP revealed a unique genomic identity for B. spinosa which discriminated it from human pathogenic isolates of Burkholderia. No antagonists were present in edible parts of banana treated with the most effective postharvest treatment as determined by the present study. Based on these findings, it is concluded that B. spinosa which is an indigenous antagonist is a promising candidate to be used in biological control of postharvest diseases of banana.

First Report of Lasiodiplodia Fruit Rot of Jackfruit in Taiwan.

Jackfruit (Artocarpus heterophyllus Lam.) is a tropical fruit that is native to India. Five diseases, including Rhizopus fruit rot and anthracnose fruit rot, have been recorded in Taiwan (2). In 2003, brown lesions were observed on mature or harvested fruits at the Chiayi Agricultural Experiment Branch. The disease caused fruits to collapse and was easily distinguished from anthracnose and Rhizopus fruit rot. In the field, Rhizopus fruit rot was characterized by black flocci sporangia and mycelia covering the flowers and young fruits. Lasiodiplodia fruit rot often occurred on mature or wounded fruit and diseased fruit were covered with gray or black flat mycelia under humid conditions. In the early stage of Lasiodiplodia fruit rot, tiny yellow-brown lesions appeared on the peel. The lesions could rapidly expand to 10 cm in diameter within 5 days and became dark brown with a light margin. The rot symptoms progressed quickly from the peel surface into the sarcocarps that eventually turned black and soft. A fungus was isolated from the margin of the lesions and cultured on acidified potato dextrose agar (PDA) (pH 3.8). The morphology of the fungus was similar to Lasiodiplodia theobromae (Pat.) Griff. & Maubl. (synonym Botryodiplodia theobromae Pat.), which causes the stem-end rot of mango, papaya, and banana in Taiwan. The fungus grew well and produced pycnidia and conidia on PDA. Young conidia were ovate, hyaline, and thin walled without septa. Mature conidia (20 to 28 × 12 to 15 μm) were dark brown and thick walled with one median septum and longitudinal striations. The internal transcribed spacer (ITS) sequence of ribosomal DNA of this fungus was submitted to GenBank (Accession No. EU 407235) and showed 100% sequence identity with that of Botryosphaeria rhodina (anamorph Lasiodiplodia theobromae; GenBank Accession No. DQ458890). On the basis of morphological and molecular criteria, the fungus was identified as L. theobromae (1). Three healthy jackfruit fruits were wounded and inoculated with 2 × 2 mm mycelial agar plugs of the fungus from a monoconidial culture. A sterile agar plug was placed on the wounded site as a control. The fruits were kept in a box to maintain high humidity for 2 days at room temperature. Brown lesions were observed on all inoculated sites 6 days post infection. The pathogen was reisolated from the lesions of inoculated fruits, fulfilling Koch's postulate. The experiment was repeated twice. To our knowledge, this is the first report of L. theobromae causing fruit rot of jackfruit in Taiwan.

Mango stem-end rot (Botryosphaeria dothidea) disease control by partial-pressure infiltration of fungicides

The in vitro efficacy of several fungicides against Botryosphaeria dothidea (syn. Dothiorella dominicana) and their in vivo efficacy in controlling mango cv. Kensington Pride stem-end rot on partial-pressure infiltration v. dip treatment of green mature fruit was evaluated. In vitro sensitivity of B. dothidea to Benlate (benomyl), Sportak (prochloraz) and Scala (pyrimethanil) at 10 dilutions of the manufacturer's recommended rate was first determined at typical cold (13partial-pressure infiltration and conventional hot (52evaluated using the commercially recommended rate for each fungicide. In vitro, Benlate and Sportak prevented the growth of B. dothidea at both storage temperatures and at all concentrations, while Scala partially controlled growth of the pathogen. Benlate was the most effective fungicide for stem-end rot control. Sportak and Scala resulted in stem-end rot control when applied by partial-pressure infiltration, but not as dips. Partial-pressure infiltration holds promise for enhancing the efficacy of otherwise less effective but alternative fungicides for control of stem-end rot diseases.

Mango stem end rot pathogens ‐ Fruit infection by endophytic colonisation of the inflorescence and pedicel

SummaryThe stem end rot pathogens of mango (Mangifera indica), (Dothiorella dominicana, Dothiorella mangiferae, Lasiodiplodia theobromae (Syn. Diplodia natalensis Phomopsis mangiferae, Cytosphaera mangiferae, Pestalotiopsis sp. and Dothiorella‘long’), as well as other fungi (including Alternaria alternata), were found to occur endophytically in the stem tissue of mango trees prior to inflorescence emergence. On samples from trees with a record of low stem end rot levels, colonisation did not extend into the most recently produced flush of stem tissue. At a site with a history of high stem end rot levels, sequential monitoring of inflorescence tissue between flowering and harvest by plating out small (c. 8 mm3) tissue pieces revealed, that at least some of the pathogens ‐ Dothiorella spp., P. mangiferae, Pestalotiopsis sp. and C. mangiferae gradually colonised the inflorescence, reaching the pedicel tissue of young fruit ‐ 8 wk after flowering. Subsequently, detection frequency of the pathogens in inflorescence tissue declined, possibly because of interference from copper residues (from field sprays) accumulating on tissue samples. The detection frequency of A. alternata also increased as Dothiorella spp. declined, however these changes could not be attributed to antagonistic interactions between the two fungi.Using larger tissue pieces (1–2 mm thick transverse sections, or a square of tissue 25 mm2× 3 mm thick) in isolations, endophytic colonisation by Dothiorella spp. and P. mangiferae was detected in stem, inflorescence and pedicel tissues of mature‐fruit‐specimens from two different sites, one unsprayed, and the other regularly sprayed with copper. The fungi were detected more frequently in the samples from unsprayed trees. Fruit from the sprayed orchard subsequently developed a high level of stem end rot caused by D. dominicana, while a lower level of stem end rot developed in unsprayed fruit, possibly because the latter fruit were also extensively diseased by anthracnose (Colletotrichum gloeosporioides Penz.). Endophytic colonisation of inflorescence and pedicel tissue was found to be a primary route of infection for fruit which develop stem end rot during ripening.

Mango stem end rot pathogens — Infection levels between flowering and harvest

SummaryDuring flowering and fruit set of mango (Mangifera indica L.), colonisation by fungi (Alternaria alternata, Cladosporium cladosporioides, Dothiorella dominicana, Dothiorella mangiferae, Dothiorella sp., Epicoccum purpurascens and Pestalotiopsis sp.) increased as the flowers senesced and young fruit formed.In the third week after flowering, the incidence of Dothiorella dominicana and Dothiorella mangiferae associated with mango fruit‐pedicel connection tissue declined coincidentally with early fruit‐fall, suggesting that early infections by Dothiorella spp. may cause fruitlet abortion. Dothiorella spp. levels in fruit‐pedicel connection tissue remained low for the subsequent 6 weeks, after which they increased. By 16 weeks after flowering, the incidence of Dothiorella spp., determined by isolation from fruit‐pedicel connection tissue, was similar to the incidence of stem end rot caused by Dothiorella spp., which developed in fruit harvested at that time. By contrast, the frequency of detection of Dothiorella spp. in peduncle tissue peaked 11 weeks after flowering, when the levels of stem end rot developing in fruit were already similar to the levels recorded in fruit harvested at 16 weeks and later.The results suggest that in fruit and fruit‐pedicel tissue, colonisation might arise from Dothiorella spp. occurring endophytically in the peduncle. The earliest indicator of stem end rot incidence at harvest was the infection level in peduncle tissue sampled 11 weeks after flowering. Early assays of peduncle tissue for Dothiorella spp. might prove useful for selecting crops with low stem end rot infection levels.

Growth and infectivity of Botryodiplodia theobromae causing stem-end rot of mango

Botryodiplodia theobromae grew and sporulated best at 28°C on media amended with ripe mango-extract and dextrose or sucrose. Agar amended with unripe mango pulp caused a reduction in the growth rate. A pink pigment was secreted into the medium, with the highest rate of production at 32°. Inoculation of mangoes with B. theobromae produced infections, especially above 25°, only when fruits began to ripen. Evidence for a possible quiescent infection was obtained. The presence of a long pedicel delayed infection by 2–3 d compared to non-pedicellate fruits.

Post-harvest storage control of mango stem-end rot with fungicidal dips

Stem-end rot, Lasiodiplodia theobromae (Pat.) Griff. and Maubl. was controlled in harvested mango fruit for up to 4 weeks by fungicidal dipping of pared fruit followed by storage at 13�C. Stem-end rot was significantly (P< 0.05) reduced by a 0.025% prochloraz dip at an ambient water temperature of 31�C or by a 0.05% benomyl dip at 50�C water temperature, com pared with ambient water dipping at 31�C. A hot water dip at 50�C, or 0.1% thiabendazole at 50�C water tem perature, did not significantly control stem-end rot.