Crown Rot Of Bananas Research Articles

GC-MS profiling and antifungal activities of Morinda citrifolia L. leaf extract against fungal pathogens of crown rot disease of banana

The increasing demand for organic agricultural products especially among the elite stimulated the search for safe and alternative means of crown rot disease control. Morinda citrifolia is one of the listed medicinal plants among the Polynesian countries. This study documented the phytochemical profile of M. citrifolia using GC-MS and their antifungal activities against crown rot pathogens. The key phytochemical constituents of the extract were Phytol 2-Hexadecen-1-ol, (Diterpene) (25.96%), Squalene (Triterpene) (15.13%), 1, 3-Propanediol (Polyphenol) (4.68%), Pyran-4-one 4H-, 9 (Flavonoid), and 2H-1-Benzopyran-6-ol (Vitamins) (5.14%), 2-Cyclohexan-1-one, (Phenol) (2.54%). Fungal pathogens; Lasiodiplodia theobromae, Colletotrichum musae, Colletotrichum asianum and Fussarium Longipes isolated from crown rot infected banana fruits during earlier studies were used in this experiment. The poisoned food technique method was adopted in evaluating the inhibitory effect of the leaf extract against the fungal isolates. Results indicated significantly high fungal growth inhibition (P< 0.05) in concentration dependent manner on amended PDA media. 100% pathogen radial growth inhibition in all isolates was recorded at 100 mg/mL concentration. Therefore, findings of this study suggest application of leaf extract of M. citrifolia is a potential safe and alternative control of banana crown rot.

Possible mechanism of contribution of a secreted aspartic proteinase FpOPSB to the virulence of Fusarium proliferatum causing banana crown rot

AbstractFusarium proliferatum is one of the pathogenic fungi causing crown rot that results in quality deterioration and commercial value loss of banana fruit during postharvest storage. Secreted proteins from pathogenic fungi can be delivered into hosts to suppress plant immunity and establish infection. We reported here a secreted aspartic proteinase OPSB (FpOPSB) that was active during F. proliferatum infection on banana peel. FpOPSB exhibited protease activity based on in vitro assay. Immunohistochemistry assay along with subcellular localization analysis demonstrated that FpOPSB can be secreted into banana peel and localized in cytoplasm. FpOPSB deletion mutant (Δopsb) showed reduced virulence on banana fruit but no obvious effect on fungal growth compared with wild‐type. Subsequently, scanning electron microscopy results suggested that FpOPSB was important for conidial production and infectious growth as well as spreading of F. proliferatum in banana peel. Heterologous expression of FpOPSB in tobacco significantly enhanced plant susceptibility to F. proliferatum. Further, seven proteins were identified as potential targets of FpOPSB in banana peel using immunoprecipitation–mass spectrometry (MS)/MS, including pathogenesis‐related 10, thioredoxin H1, nonsymbiotic hemoglobin 2, fructokinase‐1, patellin‐1, leucine aminopeptidase 2, and l‐lactate dehydrogenase A. Taken together, our results confirmed that the secreted FpOPSB is a critical virulence factor of F. proliferatum when infecting banana fruit. Additionally, we postulated that FpOPSB might interfere the host immune system or neutralize the host defenses, thereby contributing to the pathogenicity of F. proliferatum. We propose aspartic proteinase as a new potential target for controlling fungal disease of postharvest fruit.

First report of Lasiodiplodia iraniensis causing crown rot on banana fruits in Brazil.

Banana is a fruit of great importance in Brazil and crown rot cause considerable damage and losses (Ploetz et al. 2003). The disease is associated with fungal complexes, especially the Lasiodiplodia theobromae sensu lato (Kamel et al. 2016; Renganathan et al. 2020; Waliullah et al. 2022). Three asymptomatic bunches of banana cv. 'Prata Catarina' were collected in Russas, Brazil (04°58'11.6"S, 38°01'44.5"W), in 2017. The samples were disinfected (NaClO, 200 ppm), and incubated in a moist chamber at 28 °C, with 12 h light/12 h dark for 3 days. With the appearance of the symptoms (32% of severity), the isolation was conducted in potato dextrose agar (PDA). A monosporic culture (BAN14) was obtained from a typical crown rot lesion, which was subjected to morphological characterization, showing abundant aerial mycelium of olivaceous grey color on the surface and greenish grey on the back (Rayner 1970) in PDA after 15 days at 28 °C. The growth rate was 28.2 mm. day-1. The fungus produced pycnidia and conidia on water agar medium containing pine needles, with 3-4 weeks at 28 °C, presenting conidia initially aseptate, subglobose to subcylindrical, becoming pigmented with 1-central transverse septum and longitudinal striations 23.5 (18.7) 26.0 x 12.7 (9.7) 14.8 µm (n=50). Paraphyses, hyaline, cylindrical, thin-walled, apparently coenocytic with rounded apex, with length and width dimensions of 34 (43.8) 53.2 x 2.1 (2.5) 3.2 µm (n=30). Conidiophore absent, conidiogenous cells hyaline, smooth and with thin walls. The genomic DNA was extracted and amplified by PCR with primers TEF1-688F/TEF1-1251R, ITS1/ITS4, and Bt2a/Bt2b, and sequenced in both directions (O'Donnell et al. 1998; O'Donnell et al. 2010) (GenBank accession ON975017 [TEF1], ON986403 [TUB2], and ON921398 [ITS]). BLASTn analysis of TEF1, TUB2 and ITS sequences in NCBI database showed 99 to 100% nucleotide identity to a representative isolate of Lasiodiplodia iraniensis (IRAN921). Phylogenetic analysis using maximum parsimony based on the combined TEF1, TUB2 and ITS sequences indicated that the BAN14 formed a supported clade (82% bootstrap value) to L. iraniensis. The pathogenicity was evaluated in 20 banana fruit cv. 'Prata Catarina', at the point of harvest. For inoculation, the bananas were washed with water and soap, and disinfected with NaClO (200 ppm). Posteriorly, two wounds were made on the extremities of the fruits, in which were deposited mycelial discs of 5 mm in diameter, with 7 days of the growth on PDA. After inoculation, the fruits were incubated in plastic boxes in a wet chamber at 25 °C, with 12 h light/12 h dark for 5 days. The control fruits were not inoculated with the pathogen, only with PDA discs. The experiments were repeat twice. The BAN14 isolate was pathogenic to the banana cv. 'Prata Catarina'. The BAN14 was grouped with the species L. iraniensis described by Abdollahzadeh et al. (2010) in Iran. This species is distributed in Asia, South and North America, Australia, and Africa. In Brazil it was reported in association to Anacardium occidentale, Annona muricata, A. squamosa, Annona ×cherimola-squamosa, Citrus sp., Eucalyptus sp., Jatropha curcas, Mangifera indica, Manihot esculenta, Nopalea cochenillifera, Vitis sp. and V. vinifera. Until the moment, there is not description of the relation between banana crown rot and L. iraniensis (Farr and Rossman 2022). Our work is the first report on the pathogenicity of this species on banana fruit cv. 'Prata Catarina' worldwide.

First Report of Crown Rot of Banana Caused by Fusarium proliferatum in Georgia, U.S.A.

Crown rot is one of the most damaging disease of banana fruit characterized by rot and necrosis of crown tissues. In severe cases, the disease can spread to the pedicel and banana pulp. Crown rot can be infected by several common fungi, including Lasiodiplodia theobromae, Musicillium theobromae, Colletotrichum musae, and a complex of Fusarium spp. and lead to softening and blackening of tissues (Lassois et al., 2010; Kamel et al., 2016; Triest et al., 2016; Snowdon, 1990). In November 2020, typical crown rot of banana fruits (cv. Pisang Awak, belonging to the tetraploid AABB genome) were observed from UGA Banana Research 12 Plots, Tifton, GA, with incidence rates of 15%. Initial symptoms appeared in the infected crown of green banana fruits. As the infection progressed, the crown tissues became blackened and softened, followed by an internal development of infection affecting the peduncle and the fruit, triggered early ripening of bananas. At last, the development of necrosis on the pedicels and fruits appeared and caused the fingers to fall off. To identify the pathogen, tissue pieces (~0.25 cm2) from the infected crown and pedicles were surface-sterilized in a 10% bleach solution for 1 min, followed by 30 s in 70% EtOH. The disinfected tissues were rinsed in sterile water 3 times and cultured on potato dextrose agar (PDA) amended with 50 µg/ml streptomycin at 25°C in the dark for 5-10 days. Isolates of the pathogen were purified using the single-spore isolation method (Leslie and Summerell 2006). Colonies on PDA produced fluffy aerial mycelium and developed an intense purple pigment when viewed from the underside. A range of colony pigmentation and growth rates were observed among the isolates. The microconidia were ovoid, hyaline, or ellipse in shape. The morphological features of the isolates were identified as Fusarium proliferatum (Leslie and Summerell, 2006). To further identify the isolates, genomic DNA was extracted from a representative isolate. And the internal transcribed spacer (ITS) region, the partial elongation factor (TEF1-α) gene and the β-tubulin gene (TUB2)were amplified and sequenced using the primers ITS1/ITS4 (Yin et al. 2012), EF-1 /EF-2 (O'Donnell et al. 1998) and B-tub1 /B-tub2 (O'Donnell and Cigelnik, 1997), respectively. The amplicons were sequenced and deposited in NCBI (accessions no. MZ292989, MZ293071 for ITS: MZ346602, MZ346603 for TEF1-α and MZ346600 and MZ346601 for B-tub). The ITS, TEF1-α, and B-tub sequences of the isolates showed 100% sequence similarity with Fusarium proliferatum isolates (accessions no. MT560212, LS42312, and LT575130, respectively) using BLASTn in Genbank. For pathogenicity testing, three whole bunched bananas sterilized with 10% bleach solutions and washed by sterilized water, were cut into 5 bananas per brunch. The cut surface of the banana crown was inoculated with conidial suspension (1.0 × 107 cfu/ml) of the pathogen with pipette tips. Equal number of bananas were treated with sterilized water in the same volume as a control. All bananas were sealed in a plastic bag and incubated at 25°C. After 7 days post inoculation, all inoculated bananas showed initial crown rot symptoms while no symptoms were observed on the control bananas. The fungus was re-isolated from the symptomatic tissues of infected bananas and confirmed to be genetically identical to F. proliferatum of the original inoculated strains according to morphological characteristics and molecular identification, fulfilling Koch's postulates. To the best of our knowledge, this is the first report of F. proliferatum causing crown rot on bananas in Georgia, USA.

Telomere to Telomere Genome Assembly of Fusarium musae F31, Causal Agent of Crown Rot Disease of Banana.

Fusarium musae causes crown rot of banana and it is also associated to clinical fusariosis. A chromosome-level genome assembly of F. musae F31 obtained combining Nanopore long reads and Illumina paired-end reads resulted in 12 chromosomes plus one contig with overall N50 of 4.36 Mb, and is presented together with its mitochondrial genome (58,072 bp). The F31 genome includes telomeric regions for 11 of the 12 chromosomes representing one of the most complete genomes available in the Fusarium fujikuroi species complex. The high-quality assembly of the F31 genome will be a valuable resource for studying the pathogenic interactions occurring between F. musae and banana. Moreover, it represents an important resource for understanding the genome evolution in the F. fujikuroi species complex.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Antifungal activity of Brazilian red propolis extract and isolation of bioactive fractions by thin-layer chromatography-bioautography

ObjectivesThis study set out to highlight the in vitro and in vivo antifungal activity of an Ethanolic Extract of Red Brazilian Propolis (EERBP) and identify bioactive fractions effective against Colletotrichum musae. MethodsActive fractions were detected by the thin-layer chromatography-bioautography method and characterised by HPLC-MSn. ResultsThe in vitro results showed that EERBP had strong antifungal properties againstC. musae (81 ± 1% inhibition at 1.6 g GAE L−1). Medicarpin, (3S)-vestitol and (3S)-neovestitol were the main compounds identified in the EERBP extract (45% of all detected peaks). Two isolated fractions displayed inhibition percentages of 35 ± 4 and 42 ± 1%, respectively, on C. musae mycelial growth compared to the EERBP extract. The biological activity of the two fractions displayed an additive effect. ConclusionA further in vivo investigation revealed that EERBP is a potential natural alternative for controlling banana crown rot.

First Report of Fusarium chlamydosporum Causing Banana Crown Rot in Fujian Province, China

First Report of <i>Fusarium chlamydosporum</i> Causing Banana Crown Rot in Fujian Province, China

Etiological agents of crown rot of organic bananas in Dominican Republic

Crown rot is a postharvest disease with a great negative impact on banana fruit quality. The infections occur at harvest, but the symptoms appear after overseas transportation. Different fungal pathogens are involved in crown rot, varying according to farming area. In this study we focused on etiology of organic banana crown rot in the Dominican Republic, which is one of the leading exporters of organic bananas. Bananas from five organic farms and their corresponding packing stations located in the Valverde province were studied. Over a period of three years, 558 banana hands were collected and a total of 5000 fungal colonies were obtained from the crown tissues and 518 representative colonies were purified, characterized and identified using morphological and molecular methods. Fungi were found in all samples from field and from packing house and were distributed in 11 genera. The fungal community was dominated by Fusarium, the most frequent genus (55%) found in more than 80% of all samples. The genus was represented by nine species; Fusarium incarnatum 53%, the most frequent, followed by Fusarium verticillioides 12%, Fusarium sacchari 12%, Fusarium proliferatum 7%, and Fusarium solani 6%. The five least frequent species were Colletotrichum musae, 7% overall frequency and found in 13% of all samples; Lasiodiplodia theobromae and Lasiodiplodia pseudotheobromae, 4% and 1% overall frequency, respectively, both species found in 7% of all samples; Nigrospora sp. 11% overall frequency, Alternaria spp. 6% overall frequency, followed by Phoma spp., Pestalotiopsis sp., Curvularia spp., Microdochium sp. and some other species, known to be saprophytes, with frequency lower than 2%. The etiological agents of crown rot disease can be ranked based on their presence and pathogenicity as follows: Fusarium incarnatum, Colletotrichum musae, Fusarium verticillioides, Fusarium sacchari, and Lasiodiplodia theobromae.

Enhancing the bioefficacy of Bacillus amyloliquefaciens DGA14 with inorganic salts for the control of banana crown rot

The efficacy of Bacillus amyloliquefaciens DGA14, sodium carbonate (SC), sodium bicarbonate (SBC) and sodium hypochlorite (SH), applied alone or in various combinations, was evaluated in vitro and in vivo. DGA14 had variable responses in 1% (w/v) salts such as normal cell growth in SBC, reduction of cell cultivability by 1000-fold in SC and total inhibition by SH. DGA14 as stand-alone treatment controlled pathogens in vitro by 70% while SC, SBC or SH by 20–45%. DGA14 + SC restricted the mycelium growth of pathogens by 88%, DGA14 + SBC by 83% and DGA14 + SH by 52%. The efficacy of DGA14 against pathogens in vitro was enhanced by 21% and 15% with the amelioration of SC and SBC, respectively. Postharvest application showed that fruit dipped for 30 min in DGA14 + SBC reduced crown rot by 93%, DGA14 + SC by 70% and DGA14 + SH by 9%. Our result indicates that the combination of B. amyloliquefaciens DGA14 with SBC managed crown rot disease comparable with synthetic fungicides without negative effects on fruit quality 14 days after treatment.

PATHOGENICITY OF ORGANISMS ASSOCIATED WITH BANANA CROWN ROT IN TWO BANANA CULTIVARS

ISHS International Conference on Postharvest and Quality Management of Horticultural Products of Interest for Tropical Regions PATHOGENICITY OF ORGANISMS ASSOCIATED WITH BANANA CROWN ROT IN TWO BANANA CULTIVARS

EFFECTS OF THE COMBINED TREATMENTS OF CHITINASE PRODUCING BACTERIUM, 1-MCP AND ACTIVE PACKAGING ON CROWN ROT DISEASE AND QUALITIES OF BANANA 'KLUAI HOM THONG'

ISHS VI International Postharvest Symposium EFFECTS OF THE COMBINED TREATMENTS OF CHITINASE PRODUCING BACTERIUM, 1-MCP AND ACTIVE PACKAGING ON CROWN ROT DISEASE AND QUALITIES OF BANANA 'KLUAI HOM THONG'

Crown Rot of Bananas: Preharvest Factors Involved in Postharvest Disease Development and Integrated Control Methods.

Crown rot is a complex disease that affects export bananas in all banana-producing countries. Usually invisible when the fruits are packed for transportation from tropical countries to distant destinations, disease symptoms occur during shipment, ripening, and storage. This disease, characterized by rot and necrosis, affects tissues joining the fingers with each other, called the crown. It may reach the pedicel and even the banana pulp when crown rot is severe. Losses from 10 to 86% have been recorded for treated and untreated bananas, respectively. In this paper, we summarize the current knowledge on crown rot disease and associated control measures that must be considered throughout the production channel in order to be effective. We suggest a new approach to this postharvest disease of bananas: that of considering fruit quality potential in the field. This new concept of preharvest quality potential is a key factor to understanding crown rot development. Fruit quality potential depends on both a physiological and a parasitic component, both of which depend on agrotechnic and pedoclimatic factors of the crop production area. The physiological component is defined as the sensitivity of the fruits to crown rot, and the parasitic component reflects the capacity of the parasitic complex to induce a level of disease. The content of this review is divided into two parts. First, the fruit quality potential at field level is addressed, with special emphasis on its physiological and parasitic components. Second, the control methods are examined at different steps of the channel, in order to give an overview of a possible integrated control strategy.

Hand position on the bunch and source-sink ratio influence the banana fruit susceptibility to crown rot disease

The postharvest development of crown rot of bananas depends notably on the fruit susceptibility to this disease at harvest. It has been shown that fruit susceptibility to crown rot is variable and it was suggested that this depends on environmental preharvest factors. However, little is known about the preharvest factors influencing this susceptibility. The aim of this work was to evaluate the extent to which fruit filling characteristics during growth and the fruit development stage influence the banana susceptibility to crown rot. This involved evaluating the influence of (a) the fruit position at different levels of the banana bunch (hands) and (b) changing the source-sink ratio (So-Si ratio), on the fruit susceptibility to crown rot. The fruit susceptibility was determined by measuring the internal necrotic surface (INS) after artificial inoculation of Colletotrichum musae. A linear correlation (r = ?0.95) was found between the hand position on the bunch and the INS. The So-Si ratio was found to influence the pomological characteristics of the fruits and their susceptibility to crown rot. Fruits of bunches from which six hands were removed (two hands remaining on the bunch) proved to be significantly less susceptible to crown rot (INS = 138.3 mm2) than those from bunches with eight hands (INS = 237.9 mm2). The banana susceptibility to crown rot is thus likely to be influenced by the fruit development stage and filling characteristics. The present results highlight the importance of standardising hand sampling on a bunch when testing fruit susceptibility to crown rot. They also show that hand removal in the field has advantages in the context of integrated pest management, making it possible to reduce fruit susceptibility to crown rot while increasing fruit size. (Resume d'auteur)

Integrated control of crown rot of banana with Candida oleophila strain O, calcium chloride and modified atmosphere packaging

An integrated approach for biological control of crown rot of banana was studied. The efficacy of three control measures, applied alone or in various combinations, was evaluated under conditions highly conducive to the development of crown rot (artificial inoculation of Colletotrichum musae at 10 4 conidia/ml). The studied measures were: application of an antagonistic yeast ( Candida oleophila strain O at 1.10 7 cfu/ml), treatment with 2% (w/v) calcium chloride, and modified atmosphere packaging of fruit (MAP) in non-perforated polyethylene bags. C. oleophila was able to grow under MAP, maintaining a large population (7.10 6 to 7.10 7 cfu/g crown) throughout the 13 days of storage. Both treatment with the antagonistic yeast and storage under MAP, applied separately, reduced crown rot significantly (by 22% and 20%, respectively, as compared to untreated controls). The effect of the yeast was the same whether it was produced in Petri dishes or in a fermentor. Calcium chloride treatment alone had no effect on C. musae. The antagonistic yeast showed a 16% higher biocontrol activity (from 26% to 42%) when applied together with 2% (w/v) calcium chloride, and the presence of this adjuvant made it possible to achieve the same protective effect with a lower yeast concentration. The highest efficacy (53%) was achieved by the combination of the three alternatives means of control and a synergistic relation has been detected between the yeast, calcium chloride and MAP. Considering the severe conditions of screening, the consistency of the results obtained in this study indicates that the integrated strategy has great potential for control of crown rot of banana under commercial conditions.

Biocontrol with Trichoderma species for the management of postharvest crown rot of banana.

Lasiodiplodia theobromae and Colletotrichum musae cause the postharvest crown rot disease complex of banana. In vitro experiments evaluated the effect of twelve isolates of Trichoderma spp. from the soil of organic banana orchards (‘native isolates’) and eight isolates of Trichoderma spp. from culture collections (‘introduced isolates’) on the two pathogens. The native and introduced Trichoderma spp. had varied antagonistic effects against the two pathogens. Eight Trichoderma spp. isolates effective in the in vitro assays were evaluated singly on fruits both at room temperature and in cold storage. Single antagonists did not satisfactorily control crown rot on the fruits as compared with the fungicide carbendazim. However, two isolates of T. viride , one of T. harzianum and one of T. koningii performed well when applied singly, and these were selected for evaluation in isolate mixtures. There was very little antagonism between these isolates. Of 11 two-way, three-way and four-way mixtures of these isolates, the four-way and a three-way mixtures reduced crown rot incidence, both at room temperature and in cold storage, giving better control than carbendazim. The study identified consortia of compatible Trichoderma antagonists with superior biocontrol potential for the management of the postharvest crown rot complex of banana.

Evaluation of Pseudomonas syringae strain ESC-11 for biocontrol of crown rot and anthracnose of banana

Pseudomonas syringae strain ESC-11 and 250 μg/ml each of thiabendazole (TBZ) and imazalil reduced crown rot of banana caused by Fusarium aff. sacchari by 30–36% and 83–86%, respectively, in laboratory experiments. Four field trials performed in Costa Rica varied in treatment combinations. In field trials 1 and 2, 125 and 250 μg/ml each of TBZ and imazalil + 0.5% or 1% alum (aluminum ammonium sulfate) and ESC-11, and 250 μg/ml each of TBZ and imazalil + 1% alum reduced rot and mold. ESC-11 alone or with 0.5% alum significantly reduced rot and mold in field trial 2. In trial 3, 50 and 100 μg/ml of TBZ alone and with ESC-11 reduced mold. In trial 4, 125 μg/ml each of TBZ and imazalil and ESC-11, and 300 μg/ml each of TBZ and imazalil reduced rot, and 50 and 125 μg/ml each of TBZ and imazalil and ESC-11, and 300 μg/ml each of TBZ and imazalil reduced mold. In three field trials, there was no significant difference among treatments for latex staining. In field trial 2 only, combinations of TBZ, imazalil, and alum with or without ESC-11, reduced anthracnose, caused by Colletotrichum musae. The complex of crown rot fungi, order of treatment application, effect of alum and fungicides on ESC-11, concentration of ESC-11, and level of disease may contribute to the variation in crown rot and anthracnose control by ESC-11. Though ESC-11 alone was not effective in reducing disease, further testing in combination with low rates of fungicide should be done.

Evaluation of fungal epiphytes isolated from banana fruit surfaces for biocontrol of banana crown rot disease

Fungi isolated from the surface of banana fruits were evaluated for in vitro antagonism towards Lasiodiplodia theobromae. Thirteen fungi exhibiting pronounced growth inhibition of test pathogens were further tested for antibiosis against Thielaviopsis paradoxa, Colletotrichum musae, and Fusarium verticillioides. Clonostachys byssicola, Curvularia pallescens, Penicillium oxalicum, and Trichoderma harzianum were antagonistic to all test pathogens. Inhibition by C. pallescens and P. oxalicum to pathogens was at a distance, while C. byssicola and T. harzianum directly parasitized and killed the pathogens. The metabolites of C. byssicola, C. pallescens, and T. harzianum significantly affected the mycelial growth and conidial germination of the pathogens. In the artificial inoculation study, the antagonists survived and colonized banana fruits after 3 d. Interfungal parasitic relationship was observed between the antagonist and pathogen on artificial media and natural substrate. Postharvest application in the packing house showed that the incidence of crown rot in antagonist-treated banana was significantly lower when compared to fungicide and untreated control fruits.

In vitro application of selected essential oils and their major components in controlling fungal pathogens of crown rot in Embul banana (Musa acuminata– AAB)

SummaryThe necessity for pesticide‐free fresh produce have prompted investigating the effect of selected essential oils and their major components on inhibition of conidial germination, appressoria formation and membrane permeability changes of the pathogens responsible for crown rot of banana. Eugenol, which is the major component of the essential oil of Ocimum basilicum, was the most effective chemical component in inhibiting conidial germination of Colletotrichum musae and Fusarium proliferatumin vitro while Cymbopogon citratus oil was the least effective. Both O. basilicum and C. citratus oils and their major components (Eugenol, citral a + b) inhibited appressoria formation by C. musae and changed the selective permeability of conidial membranes. Ocimum basilicum oil, eugenol and citral a + b could be satisfactorily used for inhibition of conidial germination and disruption of conidial activity of banana pathogens.

Biological control of crown rot of bananas with Pichia anomala strain K and Candida oleophila strain O

The antagonistic activity of two yeast strains ( Pichia anomala (E.C. Hansen) Kurtzman, strain K and Candida oleophila Montrocher, strain O) against the parasitic complex responsible for banana crown rot was evaluated. The strains were applied at three different concentrations (10 6, 10 7, 10 8 cfu/ml) and their efficacy tested in vivo on three separate fungi ( Colletotrichum musae (Berk. & Curt.) Arx, Fusarium moniliforme Sheldon, and Cephalosporium sp.) and on a parasitic complex formed by association of these three fungi. At the concentrations used C. musae appeared to be the most pathogenic. The complex showed intermediate aggressiveness between C. musae and both other fungi. Statistically significant antagonistic effects were observed on C. musae, F. moniliforme, and the fungal complex. The highest protection level (54.4%) was observed with strain O added at 10 8 cfu/ml on crowns previously inoculated with the fungal complex. The level was lower when the fungi were inoculated separately. Furthermore, the antagonistic effect was strongly reinforced when strain O at 10 8 cfu/ml was applied 24 h before fungal complex inoculation (59.9%), as compared to its application 15 min (24.3%) or 3 h (27.3%) after fungal complex inoculation. Bananas showed increased susceptibility to the fungal complex from March to June, and this influenced the level of protection by yeast, which decreased over the same period. A strict negative correlation ( R 2 = 0.83) was highlighted between susceptibility of banana to crown rot and protection provided by yeast.

Effects of cinnamon extract, chitosan coating, hot water treatment and their combinations on crown rot disease and quality of banana fruit

The antifungal activities of cinnamon extract (CE), piper extract (PE) and garlic extract (GE) were evaluated on banana crown rot fungi ( Colletotrichum musae, Fusarium spp. and Lasiodiplodia theobromae) in vitro. The assay was conducted with extracts of CE, PE and GE with concentrations of 0, 0.1, 0.5, 1.0, 5.0, 10.0 and 0.75 g L −1 of carbendazim (CBZ) on potato dextrose agar at room temperature. CE completely inhibited conidial germination and mycelial growth of all fungi at 5.0 g L −1. PE totally suppressed mycelial growth of all fungi at 5.0 g L −1 and conidial germination at 10.0 g L −1 except for Fusarium spp. GE had no significant effects but low concentrations (0.1 and 0.5 g L −1) enhanced germ tube elongation of the three fungi. The ED 50 values were higher for mycelial growth than for conidia except for Fusarium spp. Combined treatments were investigated on crown rot development in banana fruit ( Musa AAA group ‘Kluai Hom thong’). Treatments included 5.0 g L −1 CE, 1% (w/v) chitosan solution, hot water treatment (HWT, 45 °C for 20 min), CE plus chitosan, CE plus HWT and 0.75 g L −1 of CBZ, applied before and after inoculation of the fruit. Crown rot development was assessed during storage at 13 °C for 7 weeks. Disease development was least (25%) on CE treated fruit after inoculation compared to CBZ but was higher when CE was applied before inoculation. Chitosan significantly delayed ripening as in terms of peel color, firmness, soluble solids and disease severity. CE showed no negative effects on quality of fruit. CE plus HWT caused unacceptable peel browning.