Disease Of Papaya Research Articles

Machine vision based papaya disease recognition

Over the years little research has been performed for vision-based papaya disease recognition system in order to help distant farmers, most of whom require proper support for cultivation. Due to advancement of vision-based technology we find a good solution to this problem. Papaya disease recognition mainly involves two challenging problems: one is disease detection and another is disease classification. Considering this scenario, here we present an online machine vision-based agro-medical expert system that processes an image captured through mobile or handheld device and determines the diseases in order to help distant farmers to address the problem. Some experiments are performed to show the utility of the proposed expert system. First, we propose a set of features from the view point of distinguishing attributes. K-means clustering algorithm is used in order to segment out the disease-attacked region from the captured image and then required features are extracted to classify the diseases with the help of support vector machine. More than 90% classification accuracy has been achieved, which appears to be good as well as promising by comparing performances obtained with recently reported relevant works.

First report of <i>Chryseobacterium indologenes</i> as causal agent for crown rot of papaya (<i>Carica papaya</i> L.) in peninsular Malaysia

Bacterial strains were isolated from papaya plants showing the crown rot symptoms in peninsular Malaysia. Greasy and water-soaked lesions were observed on petiole axis, young stems and buds of the plants. Bacteria were then identified using the Biolog system showed that the bacterium was Chryseobacterium indolegenes with a similarity (SIM) index of between 0.5 and 0.74 at 24 h of incubation followed by standard morphological and biochemical tests. The isolates were then confirmed by Polymerase Chain Reaction (PCR) and sequencing of the 16S rRNA gene and was successfully identified as C. indologenes with a 100% sequence similarity with reference strain (C. indolegenes strain LMG 8337; GenBank Acc. No: NR_042507.1). C indolegenes was consistently isolated from diseased papaya plants and the pathogenicity was confirmed by Koch’s postulate.Keywords: papaya crown rot; Chryseobacterium indologenes

Alternative control of post-harvest diseases in Tainung 1 papaya

ABSTRACT Controlling post-harvest papaya diseases without using agrochemicals is a challenge for producers. This study aimed at evaluating the effect of clove essential oil, biological fungicide (Trichodermil®), resistance inducer (Cob Sistem®) and chemical fungicide (Imazacure®) on the in vitro control of phytopathogenic fungi isolates from papaya as well as on the post-harvest quality of Tainung 1 papaya. The in vitro experiment was conducted in a complete randomized design, with five fungal species x five treatments and five replications. The in vivo experiment was conducted in a complete randomized design, with five treatments x five storage times, five replications and three fruits per replication. The fruits were stored under refrigeration at 10 ± 2 ºC and 90 ± 5 % of relative humidity and evaluated at 0, 7, 14, 21 and 28 days of storage, plus two shelf life days at 25 ± 2 ºC, to simulate marketing conditions. The inhibition of mycelial growth was evaluated in the in vitro experiment, while the diseases occurrence and post-harvest quality of the fruits were evaluated in the in vivo experiment. The clove essential oil and Trichodermil® were as efficient as Imazacure® in inhibiting the mycelial growth of Alternaria sp., Colletotrichum gloeosporioides and Rhizopus sp. The treatments with clove essential oil, Trichodermil® and Imazacure® were similar in controlling the pathogens up to 21 days of storage. The treatments had no effect on the fruits soluble solid contents.

Selection of fungi with biocontrol potential against the black spot disease of papaya1

ABSTRACT The use of fungicides is the main control measure against the black-spot disease of papaya. The biological control is an alternative to that, being the selection of mycoparasitic fungi the first step in programs aiming at this kind of control. This study aimed to obtain and select fungi with potential to the biocontrol of the black spot disease of papaya. For this purpose, 24 isolates were collected from different regions and pathosystems, and then identified morphologically and by the ITS region sequencing. In order to evaluate the mycoparasite potential, two assessments, in a randomized block design, with three replications, were carried out in a shadehouse, being the obtained isolates inoculated on papaya leaves with black spot lesions. The average time for the appearance of mycoparasitism signs and the incidence of mycoparasitized black spot lesions were evaluated. Of the 24 isolates obtained, ten were from Hansfordia pulvinata, two from Lecanicillium lecaniium, two from Simplicillium lanossoniveum, one from Sarocladium implicatum and nine from Acremonium spp. A wide variability, concerning the mycoparasitism on black spot lesions, was observed, especially for the isolates H-611, H-613, H-614 and H-615, which showed the highest colonization averages. The results demonstrate that H. pulvinata has a great potential to be used as a biocontrol agent against Asperisporium caricae.

Identificación de especies del género <i>Colletotrichum</i> asociadas a la antracnosis en papaya (<i>Carica papaya L.</i>) en Costa Rica1

La antracnosis, causada por Colletotrichum spp., es una de la enfermedades poscosecha más importantes en papaya. En este estudio, frutas de papaya, híbrido Pococí, recolectados en plantaciones ubicadas en el cantón de Guácimo, provincia de Limón, presentaron 7 síntomas de antracnosis, luego de un período de almacenamiento. De cada síntoma se obtuvieron aislados de Colletotrichum en medio de cultivo PDA (papa-dextrosa-agar). Los aislamientos se clasificaron en 3 grupos según la similitud de los síntomas y la morfología de la colonia. El análisis de la secuencia de la región espaciadora interna transcrita (ITS) del ADN ribosomal reveló que los aislamientos pertenecieron a 3 especies del género Colletotrichum: C. gloeosporioides sensu lato, C. magnum y C. capsici (C. truncatum). La identificación de las especies fue confirmada con imprimadores taxón específico para C. gloeosporioides e imprimadores especie-específicos para C. magnum. Las 3 especies identificadas mostraron ser patogénicas sobre frutas de papaya. Las especies C. magnum y C. capsici (C. truncatum) se registran por primera vez en Costa Rica, como agentes causales de la antracnosis en papaya.

EVALUATION OF INOCULATION TECHNIQUES TO SCREEN FOR BACTERIAL CROWN ROT RESISTANCE IN DIFFERENT BREEDING LINES OF CARICA PAPAYA

Bacterial crown rot (BCR) is considered as the most destructive disease of papaya in the Philippines. The use of resistant cultivars with acceptable horticultural traits remains the most effective and economical strategy to manage the disease. This study was conducted to develop a rapid and effective inoculation technique that could be used to screen for BCR resistance in a papaya breeding program. Furthermore, papaya breeding lines and germplasm collections were evaluated using the inoculation technique to identify promising materials that can either be released as commercial cultivars or used as parental lines. Different isolates of Erwinia mallotivora collected from Luzon and Mindanao, Philippines were pathogenicity tested to papaya seedlings cv. ‘Solo’. The most aggressive and virulent isolate was identified and used in the evaluation of various inoculation techniques. The leaf abrasion technique proved to be the most effective of the five inoculation techniques that were assessed namely: a) stem injection, b) pricking, c) leaf clipping, d) drenching and e) leaf abrasion. This technique was able to differentiate levels of resistance/susceptibility of the different breeding lines and cultivars. Fiftynine of the eighty parentals/inbreds/lines that exhibited resistance in the field with high BCR incidence were further evaluated using the leaf abrasion technique in the screen-house. Of these, nine parental lines, six inbred lines and five accessions exhibited resistance to BCR. These materials are now being grown in the field for horticultural trait evaluation.

Antioxidant-mediated response of a susceptible papaya cultivar to a compatible strain of Erwinia mallotivora

Dieback disease caused by Erwinia mallotivora is the most devastating disease of papaya in Malaysia. Most papaya cultivars here are susceptible to the disease, indicating a compatible relationship between the cultivars and the pathogenic strains of the bacteria. In this study, we evaluated early responses of a susceptible cultivar to a virulent strain of the bacteria by monitoring the disease symptoms, measuring the expression patterns and activities of the oxidative enzymes superoxide dismutase (SOD) and peroxidase (POD), and profiling the leaf proteome. Water-soaked lesions and necrotic spots were evidenced on the inoculated leaves at 6 days post-inoculation (dpi) which were deteriorated rapidly with death at 12 dpi. The two oxidative enzymes were responsive to the infection as shown by their induced enzymatic activities and gene expressions in the leaves of the infected plants. The 2D-PAGE profile of the leaf proteome exhibited a significant increase in the intensity of the SOD spot, confirming its involvement in the response. In addition, differential expressions of the protein spots known to be related to stress response, energy production and photosynthesis provided insights into the plant's global response to the infection. Overall, this study suggested that the early response to E. mallotivora inoculation in the susceptible papaya cultivar was likely to be mediated by the antioxidant defense system but the effectiveness of the defense could have been compromised with the down-regulation of important proteins required for normal plant growth and development. This study provides the basis for studying the defect in the defense mechanism that turned this cultivar susceptible to the infection.

New strains of chickpea chlorotic dwarf virus discovered on diseased papaya and tomato plants in Burkina Faso

This is the first description of full genome sequences of chickpea chlorotic dwarf virus (CpCDV; genus Mastrevirus; family Geminiviridae) identified in papaya and tomato plants sampled in Burkina Faso. The CpCDV full genome sequences from papaya and tomato share the highest pairwise sequence identity (84% and 93.5%) with Sudanese isolates of the CpCDV-K and CpCDV-M strains, respectively. Based on the strain demarcation threshold (>94% identity) for mastreviruses, we propose two new strains, CpCDV-Q and CpCDV-R, identified in papaya and tomato, respectively. Phylogenetic analysis confirmed that the sequences belong to a distinct clade of the highly diverse population of CpCDVs. Evidence of inter-strain recombination provided more support for the important role of recombination in CpCDV evolution. The discovery of CpCDV on papaya, a previously unsuspected host, raises many questions about the natural and potential host range of this dicot-infecting mastrevirus species that is reported to be emerging worldwide.

‘Candidatus Phytoplasma brasiliense’-related strains associated with papaya bunchy top disease in northern Peru represent a distinct geographic lineage

During the 2015–2016 fruit production season, a papaya bunchy top (PBT) disease was observed in a papaya production farm located at Region de Piura, northern Peru. Affected plants exhibited symptoms of excessive proliferation of auxiliary shoots at the top or near top of the main stem, shortening of internodes, leaf yellowing, and necrosis of leaf veins. The symptom syndrome suggested possible infection by a phytoplasma, and the recent discovery of a phytoplasmal disease in a nearby vineyard also indicated that a phytoplasma reservoir and potential vector(s) were present in the area. Molecular diagnostic assays for phytoplasma detection were therefore employed. Nested polymerase chain reactions and subsequent nucleotide sequence analysis confirmed that phytoplasma infection did occur in the papaya production farm. The phytoplasma strains found to be associated with the PBT disease are affiliated with ‘Candidatus Phytoplasma brasiliense’, a species that had previously never been implicated in a papaya disease anywhere in the world. We provide molecular evidence to suggest that the papaya-infecting phytoplasma strains identified in this study are closely related to a phytoplasma associated with the first grapevine yellows (GY) disease that we recently identified in Peru. The results of our study indicate that these PBT and GY phytoplasma strains in Peru represent an emerging geographic lineage that is distinct from those of all other known ‘Ca. Phytoplasma brasiliense’ strains in the Americas.

In vivo efficacy of garlic extract and yeast for the control of post harvest diseases of mango and papaya

The present investigations were carried out with collection of diseased samples, isolation of the organisms responsible for post harvest spoilage, their pathogenicity, symptomatology and morphological characters in order to suggest suitable control measures in respect of yeast as a bioagent and garlic extract as a botanical in controlling post harvest fungal diseases of mango and papaya. The causal organisms was isolated from infected fruits and recorded association of four fungal pathogens viz., Aspergillus niger, Colletotrichum gloeosporioides, Alternaria alternata, and Rhizopus stolonifer. The pathogenicity of all pathogens was proved by artificial inoculation method. The conidial size of A. niger, A. alternata, , C. gloeosporioides, and R. stolonifer measured as 4.4 μm, 42.47 x 16.37 μm, 9.50 – 18.56 x 2.68 -6.72 μm and 125 x 294.1 μm in size (average), respectively. Use of 5 per cent yeast, (Eremothecium cymbalariae) was found effective against Aspregillus niger and Colletotrichum gloeosporioides .1 per cent garlic extract was found effective against Colletotrichum gloeosporioides and Alternaria alternata, but not much effective against Alternaria alternata on papaya fruits. Both yeast and garlic extract increases shelf-life and market quality of fruits, with increase in glossiness of fruits. How to view point the article : Shinde, R.P., Barhate, B.G. and Musmade, N.A. (2016). In vivo efficacy of garlic extract and yeast for the control of post harvest diseases of mango and papaya. Internat. J. Plant Protec., 9(2) : 632-634, DOI : 10.15740/HAS/IJPP/9.2/632-634.

Aphid vectors of Papaya ringspot virus and their weed hosts in orchards in the major papaya producing and exporting region of Brazil

Papaya ringspot, one of the most important diseases of papaya, is caused by Papaya ringspot virus type P (PRSV-P), which is transmitted by various aphid species. Objectives of this research were to identify the aphid species and their weed hosts of papaya orchards in the major papaya producing and exporting region of Brazil in northern Espírito Santo State. Aphids were collected from weed hosts, and with Möericke-type traps in papaya orchards of twenty farms in Linhares, Sooretama and Aracruz municipalities of Espírito Santo, Brazil. A total of forty aphid species were collected, of which 22 are new records in the State. Thirty-eight aphid species were identified from traps, including Aphis craccivora Koch, A. gossypii Glover, A. spiraecola Patch, Myzus persicae (Sulzer), and Toxoptera citricidus (Kirkaldy), known vectors of PRSV-P. Cryptomyzus Oestlund (Aphididae) is recorded for the first time in Brazil. Thirteen aphid species associated with 22 weed species of 14 families were collected. Aphis gossypii, which has been reported to be one of the most efficient vectors of PRSV-P, infested the greatest number of weed hosts. Chamaesyce hyssopifolia (L.) Small, Euphorbia hirta L. (Euphorbiaceae), Commelina benghalensis L. (Commelinaceae), Lepidium virginicum L. (Brassicaceae) and Sida sp. (Malvaceae) were the most frequently infested weeds. Commelina benghalensis was infested by the greatest number of aphid species during this study. Integrated management of weed hosts of aphids to reduce aphid populations in papaya orchards may be useful for control of PRSV-P. Based on accurate knowledge of the aphid and weed species present in papaya orchards obtained in this study, integrated pest management efforts may be more efficiently directed toward eliminating the most frequently infested weed species that serve as hosts for aphid vectors of PRSV-P.

Integrated Management of Root Rot Disease of Papaya (Carica papaya L.) caused by Fusarium solani

Present study the most effective fungicides, plant extract, organic cake and bio-agent were evaluated in different combinations under field conditions for the management of papaya root rot disease. It was observed that there was 81.5% disease incidence in control while the lowest disease incidence (29.60%) was recorded in treatment (T ) (Comprising disease free seedling + mustard 13 cake (10%)+ wild garlic (10%) + dipping of seedlings in thiophanate methyl (0.1%) 30 min.+ soil drenching with thiophanate methyl (0.1%) solution three times (1st at time of transplanting, second at 3rd MAT and third at 5th month after transplanting)+ Soil application of Trichoderma viride @ 50g/plant three times (i.e. 1st at time of transplanting, second at 3rd MAT and third at 5th MAT)+ soil application of Pseudomonas florescence @ 50g/plant three times (i.e. 1st at time of transplanting, second at 3rd MAT and third at 5th MAT). This was followed by treatment T (37.0%), T (40.7%) and T 6 9 5 (44.4%). The effect of different treatments on yield was also studied and the highest fruit yield (1064.67 kg/plot) was obtained from the treatment T followed by treatment T (848.67 kg/plot) and 13 9 T (810.00 kg/plot) over the control T (209.00 kg/plot).

Production of Active Packaging from Debris of Heliconia and Thai Herbs for Reducing Anthracnose Disease of Mango and Papaya

<p>A study of production of active packaging from debris of Heliconia and Thai herbs for reducing anthracnose disease of mango and papaya comprises four steps: 1) create mold for producing packaging 2) prepare pulp from agricultural waste, 3) produce active packaging, and 4) test of packaging efficiency to reduce anthracnose disease in mango and papaya. The study revealed that creating mold from white cement was easy and quick, and the mold was strong. Regarding the method to produce packaging, pouring of pulp onto muslin cloth in the mold did not give uniform thickness, whereas hand tapping of pulp into the mold offered uniform thickness but it took more time to do. However, the latter took only one day to dry while the first took 2-3 days. The packaging was less shrink by tapping than pouring method. The shape of packaging can well support mango and papaya fruits, and its strength and thickness was adjustable by the amount of pulp used. Heliconia pulp can be used to produce packaging and provided natural color as well as the identity of hand-made products which is free from harmful chemicals in the pulping process. The active packaging produced from Heliconia pulp and herbal extracts from galangal stem, kaffir lime leaves, cassia leaves and Plai essential oil was found to be effective in controlling anthracnose disease. The anthracnose lesions on mango fruits were smaller than those on papaya fruits.</p>

The dsRNA Virus Papaya Meleira Virus and an ssRNA Virus Are Associated with Papaya Sticky Disease.

Papaya sticky disease, or “meleira”, is one of the major diseases of papaya in Brazil and Mexico, capable of causing complete crop loss. The causal agent of sticky disease was identified as an isometric virus with a double stranded RNA (dsRNA) genome, named papaya meleira virus (PMeV). In the present study, PMeV dsRNA and a second RNA band of approximately 4.5 kb, both isolated from latex of papaya plants with severe symptoms of sticky disease, were deep-sequenced. The nearly complete sequence obtained for PMeV dsRNA is 8,814 nucleotides long and contains two putative ORFs; the predicted ORF1 and ORF2 display similarity to capsid proteins and RdRp's, respectively, from mycoviruses tentatively classified in the family Totiviridae. The sequence obtained for the second RNA is 4,515 nucleotides long and contains two putative ORFs. The predicted ORFs 1 and 2 display 48% and 73% sequence identity, respectively, with the corresponding proteins of papaya virus Q, an umbravirus recently described infecting papaya in Ecuador. Viral purification in a sucrose gradient allowed separation of particles containing each RNA. Mass spectrometry analysis indicated that both PMeV and the second RNA virus (named papaya meleira virus 2, PMeV2) were encapsidated in particles formed by the protein encoded by PMeV ORF1. The presence of both PMeV and PMeV2 was confirmed in field plants showing typical symptoms of sticky disease. Interestingly, PMeV was detected alone in asymptomatic plants. Together, our results indicate that sticky disease is associated with double infection by PMeV and PMeV2.

Physical Characteristics of the Leaves and Latex of Papaya Plants Infected with the Papaya meleira Virus.

Sticky disease, which is caused by Papaya meleira virus (PMeV), is a significant papaya disease in Brazil and Mexico, where it has caused severe economic losses, and it seems to have spread to Central and South America. Studies assessing the pathogen-host interaction at the nano-histological level are needed to better understand the mechanisms that underlie natural resistance. In this study, the topography and mechanical properties of the leaf midribs and latex of healthy and PMeV-infected papaya plants were observed by atomic force microscopy and scanning electron microscopy. Healthy plants displayed a smooth surface with practically no roughness of the leaf midribs and the latex and a higher adhesion force than infected plants. PMeV promotes changes in the leaf midribs and latex, making them more fragile and susceptible to breakage. These changes, which are associated with increased water uptake and internal pressure in laticifers, causes cell disruption that leads to spontaneous exudation of the latex and facilitates the spread of PMeV to other laticifers. These results provide new insights into the papaya-PMeV interaction that could be helpful for controlling papaya sticky disease.

A kinase gene potentially implicated in resistance toPapaya ringspot virusinVasconcellea quercifolia

Papaya ringspot virus type P (PRSV-P) is one of the most devastating diseases of Carica papaya (papaya). No resistance has been reported within the cultivated genome; however, resistance exists within wild related species in genus Vasconcellea. Since 1998, breeding strategies have focussed on transferring resistance alleles from V. pubescens and V. quercifolia into V. parviflora and papaya. Previously, the V. pubescens resistance was characterised at the prv1 locus, located in close proximity to two kinase (VP_STK1 and VP_STK2) and one leucine rich repeat (VP_LRR) genes. Subsequently, the functional response of these genes in V. quercifolia, and potential differential response among wild and cultivated genomes, was assessed by transcriptional profiling following PRSV-P inoculation. Initially, the resistance response within V. quercifolia was confirmed through a controlled inoculation bioassay. Following inoculation with an equal viral titer, the viral coat protein (CP) level was significantly up regulated in C. papaya compared to non-significant CP expression in V. quercifolia from 20 to 30 days after inoculation (DAI). Putative resistance genes were identified in V. quercifolia using RACE-PCR and named VQ_STK2, VQ_STK2.1 and VQ_LRR. VQ_STK2 was significantly and differentially up-regulated in V. quercifolia between 0.15 and 1.5 fold from 5 to 30 DAI. In contrast, VQ_STK2 was significantly reduced after papaya plants were inoculated to the lowest point of down-regulation of 0.6 fold expression at 20 DAI. This indicated that STK2 may have a role in the sustained viral defence mechanism present in V. quercifolia and will be a target for further functional validation.

Occurrence of phytoplasma diseases of papaya in Sri Lanka

Occurrence of phytoplasma diseases of papaya in Sri Lanka

Management options for control of damping off and root rot diseases in papaya

Management options for control of damping off and root rot diseases in papaya

Efeito dos óleos essenciais sobre a antracnose in vitro e em frutos de mamoeiro

RESUMO As doenças pós-colheita do mamão são as principais responsáveis pelas perdas que ocorrem durante esse processo. A antracnose é uma doença causada pelo fungo Colletotrichum gloeosporioides. Esse patógeno tem a capacidade de se estabelecer no fruto imaturo, permanecendo em estado latente até que as condições se tornem favoráveis ao seu desenvolvimento. O presente estudo teve como objetivo determinar o efeito fungistático dos óleos essenciais sobre o fungo C.gloeosporioides. Os experimentos foram realizados no laboratório de Fitossanidade da Universidade Estadual de Mato Grosso do Sul, Unidade Universitária de Cassilândia, foram três etapas, quais sejam: I efeito dos óleos essenciais sobre a germinação de conídios, II- ação in vitro dos óleos sobre micélios fúngicos e III- efeito dos óleos essenciais sobre o fungo em frutos do mamoeiro. Para as três fases o delineamento experimental utilizado foi inteiramente casualizado, em esquema fatorial 6 X 5, (óleos essenciais de alecrim, menta, capim-limão, anis, árvore-chá e canela) e cinco concentrações (0 μL, 10 μL, 30 μL, 50 μL, 100 μL), com 5 repetições. A germinação de conídios foi afetada drasticamente pelos óleos de menta e árvore-chá. O efeito fungitóxico do óleo de menta foi confirmado nos experimentos subsequentes, nos quais essa substância na concentração de 100 µL inibiu completamente o crescimento micelial invivo e in vitro do fungo C. gloeosporioides. Os óleos de alecrim e árvore-chá também afetam o crescimento micelial in vivo e in vitro desse fungo, embora em menor intensidade.

Effects of Plant Leaf Extract against Colletotrichum gloeosporioides (Penz) Sac. Causing Post-Harvest Disease of Papaya

The antifungal activity of selected weed and other plants leaf extract prepared in distilled water and ethanol were tested against anthracnose, the post-harvest disease of papaya (Carica papaya L.) caused by Colletotrichum gloeosporioides. The result from the experiment proved that ethanol leaf extract of weed plant, Lantana camara L.possess significant fungicidal effect on the radial growth of C. gloeosporioides followed by lemon and avocado leaf extract while Mikania micrantha Kunth, Sphagneticola trilobata (L.) Pruski and Cyperus rotundus L. leaf extract gave an insignificant inhibitory effect on the radial growth the fungus. The result of this study showed that Lantana camara leaf extract has the potential antifungal compound to control C. gloeosporioides which is the casual organism of papaya anthracnose.