Root Rot Of Melon Research Articles

A new species of Pythium hydnosporum as a pathogen associated with vine decline of melon (Cucumis melo L.) in Iraq

Several pathogenic fungi have become an important vine decline of cantaloupe melone (Cucumis melo L.). In 2021, root rot on cantaloupe was observed during the harvest phase in the fields in Penjwen and Shahrazoor in Sulaimani governorate of Northern Kurdistan region Iraq. This present study was conducted to isolate the causal agent of fungi in lesions of root rot of cantaloupe. A total of 16 fungal isolates were obtained of which isolates Monosporascus cannonballus, M. eutypoides, Acremonium vitellinium, Fusarium oxysporium, F. equiseti, Macrophomina phaseolina, Saccharomyces kudriavzevii, F. robinianum, Rhizopus arrhizus, Botrytis cinerea, Cytospora eucalypticola, F. falciforme, Pythium hydnosporum, Alternaria tenuissima, Rhizoctonia solani and Phytophthora colocasiae were obtained from root melon. Identification of all fungal isolates was based on using both morphological characteristics and molecular analysis, on internal transcribed spacer (ITS1, ITS4, LSU) are primers that are used for identification. DNA sequences of the fungal pathogen were identified as Pythium hydnosporum a new pathogenic fungi causal agent of cantaloupe vine decline. A pathogenicity test was conducted to verify Koch's postulates and P. hydnosporum was observed to cause root rot of melon, symptoms of the disease were similar to those seen in the field.

Alternative management strategies reduced the incidence and severity of root rot of melon

Alternative management strategies reduced the incidence and severity of root rot of melon

First Report of Neocosmospora falciformis Causing Wilt and Root Rot of Muskmelon in Spain

‘Cantaloupe’ and ‘Piel de Sapo’ are melon (Cucumis melo L.) varieties cultivated in Spain. In 2018, during a pathogens survey in experimental fields of Valencia and Alicante provinces (southeast Spain), wilt and root rot of melon plants were detected in grafted and ungrafted plants. Disease incidence ranged from 10% (Alicante) to 45% (Valencia). Symptoms included yellowing and wilting of leaves, rotting at the stem base and upper root, and collapse of the entire plant. Samplings were conducted from severely decayed and dead plants. Fragments (0.5 to 1 cm) from rotted lower stems and roots were surface disinfected for 1 min in 1.5% NaOCl, washed twice with sterilized distilled water, and plated onto potato dextrose agar (PDA) with streptomycin sulfate (0.5 g/liter). Plates were incubated at 25°C in the dark for 3 to 5 days. Mycelia resembling Fusarium were isolated and characterized by morphological and molecular methods. Based on their adpressed beige mycelia, growth in concentric rings, and absence of sporodochia, colonies growing on PDA and Spezieller Nahrstoffarmer agar were preliminary identified as belonging to the Fusarium solani species complex. On PDA, colonies were white-greyish to pale-cream growing in concentric rings with beige reverse after 6 days. No sporodochia were observed. Macroconidia were slender, falcate, hyaline, three to five septate 43 (38 to 47) × 4.5 (3.8 to 5.2) µm; aerial microconidia were abundant, borne on short, undifferentiated monophialides, ellipsoidal to reniform, sometimes with a truncate base, and zero to one septate 10 (9.2 to 11.4) × 3.5 (2.5 to 6) µm. Chlamydospores were globose, single or in chains, intercalary and thin- to thick-walled. Sequencing of the internal transcribed spacer (ITS) region, a fragment of translation elongation factor-1α (TEF-1α), and RNA polymerase II (RPB2) partial genes was done using ITS1/ITS4 (White et al. 1990), EF1/EF2 (O’Donnell et al. 1998), and fRPB2-7cF/fRPB2-11aR (Reeb et al. 2004) primers, respectively. After comparisons using BLASTn and the Fusarium ID database (http://www.wi.knaw.nl/fusarium/), eight isolates were identified as Neocosmospora falciformis. The ITS, EF-1α, and RPB2 sequences of isolate CRR 2-6 showed 99% homology with N. falciformis EU329691 (ITS), AB817158 (EF-1α), and EU329650 (RPB2). Sequences were deposited in GenBank with accession numbers MN086327 (ITS), MN509809 (TEF-1α), and MN509810 (RPB2). For pathogenicity tests, isolate CRR 2-6 was grown in 250-ml flasks containing potato sucrose medium for 3 days at 25°C in the dark with constant agitation. Roots of ten 15-day-old Piel de Sapo seedlings grown 6 days in trays with sterilized substrate were submerged into a suspension of 5 × 10⁶ conidia/ml for 2 min and transferred to the plastic containers. Three plants submerged in sterile water served as controls. Plants were incubated in a growth chamber (25°C; 16-h/8-h photoperiod). Scarce development, wilting, and yellowing followed by plant death were observed 15 days postinoculation. Noninoculated controls remained asymptomatic. The fungus was reisolated from all the inoculated plants and identified using ITS, TEF-1α, and RPB2. N. falciformis belongs to the Neocosmospora (Fusarium) solani species complex (O’Donnell et al. 2008). To our knowledge, this is the first report of N. falciformis causing wilt and root rot of melon in Spain. The adoption of molecular-based identification methods should lead to a more precise determination on incidence of the pathogen in this Mediterranean area.

Toxin production by melon root rot fungus, Monosporascus cannonballus

A study was conducted on the possible in vitro production of phytotoxins by the melon root rot pathogen, Monosporascus cannonballus. The culture filtrate of a highly virulent isolate of the fungus was tested for its phytotoxic activity on cucumber by detached leaf assay, electrolyte leakage assay and seedling vigour test. In detached leaf bioassay, necrotic symptoms developed on cucumber leaves 5–7 days after application of the culture filtrate. The culture filtrate of M. cannonballus caused substantial reduction in seed germination, vigor of cucumber seedlings and an increase in electrolyte leakage from leaf tissues compared to the control. Studies on the effect of heat and dialysis on the phytotoxic activity of the culture filtrate revealed that the toxic metabolites are thermostable and have low molecular weight (<14 kDa). To purify the toxin, the culture filtrate was extracted with different solvents which were then tested separately for their phytotoxicity. The results revealed that the water fraction after extraction with chloroform retained the highest phytotoxic activity. The toxin was partially purified by thin layer chromatography (TLC) and the fluorescent compound eluted with an Rf value of 0.6 was analyzed by gas chromatography-mass spectrometry (GC-MS) technique. Mass spectral analysis revealed the presence of two metabolites viz., octocrylene and squalene in the toxin fraction.

Involvement of Olpidium bornovanus and O. virulentus in the occurrence of melon root rot and vine decline caused by Monosporascus cannonballus in central Italy

Monosporascus root rot and vine decline (MRRVD), caused by Monosporascus cannonballus , has become one of the most important diseases of melon worldwide. Recent evidences suggest that M. cannonballus is not the sole cause of MRRVD, but other pathogens, Olpidium spp. and Melon necrotic spot virus (MNSV) are also involved. The aim of this study was to ascertain the potential concomitant involvement of these pathogens in the development MRRVD of melon in Central Italy analyzing a soil sampled from a greenhouse with a known history of this disease. O. bornovanus and O. virulentus along with M. cannonballus were identified from the sampled soil. Bait melon plants grown in the contaminated soil were colonized by both Olpidium species and by M. cannonballus, showing roots browning and foliage wilt. No infection by MNSV was detected in bait plants. In the tripartite pathogenicity test, O. bornovanus alone was found to be a virulent pathogen, capable of colonizing roots with a high percentage of colonization intensity, resulting in root browning and foliage wilting. Both disease severity and intensity of Olpidium colonization determined by the co-inoculation of ascospores of M. cannonballus and Olpidium spp. were statistically similar to that resulted by Olpidium or by ascospores separately inoculated. Root symptoms were accompanied by a gradual vine decline and foliage wilting. Root rot and vine decline, which was previously attributed in Central Italy primarily to M. cannonballus, needs to be reattributed, since O. bornovanus and O. virulentus are also involved without apparent synergistic effect among the pathogens.

Effects of Preconditioning Through Mycorrhizal Inoculation on the Control of Melon Root Rot and Vine Decline Caused by Monosporascus cannonballus

AbstractThe use of inoculum of arbuscular mycorrhizal fungi (AMF) in nursery represents a promising field in horticulture because of its known benefits in terms of plant growth and bioprotection. The present work was undertaken to determine the effect of mycorrhizal inoculation with Rhizophagus irregularis in a nursery medium on the containment of melon root rot and vine decline (MRRVD) caused by the soil‐borne pathogen Monosporascus cannonballus. The percentage of mycorrhization, biomass and yield following mycorrhizal inoculation were also evaluated. Biocontrol activity was assessed in greenhouse pot experiments upon artificial inoculation of M. cannonballus and in a two‐season field experiment under production conditions in an unheated greenhouse with a history of MRRVD. On the basis of the mycorrhization parameters, the interaction appeared to be established within 30 days after inoculation. The total shoot growth in the mycorrhized plants was significantly higher when compared to the control, while the root growth was unaffected. Upon artificial inoculation of M. cannonballus, mycorrhization provided complete protection against the pathogen. Greenhouse experiments under production conditions during spring cropping season showed that pretransplanting inoculation with R. irregularis significantly decreased the severity of the disease. Also, the average fruit weight of mycorrhized plants was significantly higher than the untreated control. Nevertheless, in summer crop, the bioprotection activity of AMF failed. Present results indicate that the use of AMF in a nursery setting can contribute to the prevention of the onset of this problematic soil‐borne disease within a sustainable and integrated soil‐borne disease management.

Effect of Soil Temperature Control with Colored Mulching Films on Root Rot of Melon in Hokkaido

Effect of Soil Temperature Control with Colored Mulching Films on Root Rot of Melon in Hokkaido

Effect of chemical resistance inducers on the control of Monosporascus root rot and vine decline of melon

Summary. The effect of the resistance inducers methyl jasmonate (MeJA), acybenzolar-S-methyl (BTH) and dipotassium hydrogenphosphate ( K 2HPO 4) was tested by seed soaking and by foliar application to determine whether these resistance inducers controlled root rot and vine decline of melon caused by Monosporascus cannonballus. Tests were carried out in pots and under field conditions in a two-year trial. Application of MeJA to melon seed significantly reduced symptoms of melon root rot and vine decline in soil artificially inoculated with M. cannonballus, and seeds treated with BTH and K 2HPO4 produced plants with a slightly greater resist ance to the pathogen. Greenhouse experiments in soil naturally infected with M. cannonballus in 2006 showed that MeJA treatments by seed soaking followed by foliar applications decreased the severity of the disease. In 2007, both MeJA and BTH significantly reduced root rot and vine decline, but K 2HPO4 was ineffective. The resistance inducers differentially induced the synthesis of a number of pathogenesis related (PR) protein isoenzymes, markers of induced resistance in the root system. Using MeJA to induce resistance to root rot and vine decline of melon caused by M. cannonballus may provide a practical supplement to an environmentallyfriendly disease management when it is combined with appropriate integrated agronomic practices.

Black root rot of cucurbits caused by Phomopsis sclerotioides in Japan and phylogenetic grouping of the pathogen

Although the causal agent of black root rot of Cucurbitaceae in Japan has been proposed as Phomopsis sclerotioides, the species identification of the pathogen has remained inconclusive because of a lack of spore formation. We confirmed that a Japanese isolate of Phomopsis sp. obtained from a diseased pumpkin root produced pycnidia containing α spores in sterilized bean pods. In phylogenetic analyses of rDNA-ITS regions, nine Japanese Phomopsis sp. isolates from melon, watermelon grafted onto bottle gourd, and pumpkin diagnosed with black root rot, formed a single clade with P. sclerotioides standard isolates. We identified the causal agent of the black root rot of melon, pumpkin, bottle gourd, and watermelon in Japan as P. sclerotioides and propose the Japanese name “Phomopsis-negusare-byo” for the disease. Patterns of random amplified polymorphic DNA (RAPD) of these Japanese isolates were also similar to those of P. sclerotioides, thus supporting the species identification. However, mycelial incompatibilities were found for many combinations among these P. sclerotioides isolates, suggesting some genotypic variations of this fungus in Japan at a level that the RAPD analyses cannot discriminate.

Occurrence and Pathogenicity of Fungi Associated with Melon Root Rot and Vine Decline in California.

The occurrence of fungi associated with root rot and vine decline of melon (Cucumis melo) in commercial fields in California was surveyed over 3 years. The fungi most frequently isolated from discolored vascular tissue or root rot were Acremonium cucurbitacearum, Rhizopycnis vagum, Monosporascus cannonballus, Fusarium solani, Macrophomina phaseolina, Pythium spp., and Verticillium dahliae. The frequency of isolation of the various fungi varied with root symptomology. Pythium spp., and M. phaseolina were frequently associated with a wet, brownish root rot, while A. cucurbitacearum, R. vagum, and Rhizoctonia solani were generally associated with a dry, corky root rot. Presence of Monosporascus cannonballus was associated both with a wet, brownish rot as well as with discrete, reddish, corky lesions. The frequency of isolation of a given pathogen varied with geographic location, with M. cannonballus present only in the southern production areas, while A. cucurbitacearum and Rhizopycnis vagum were most common in the northern production areas. In pathogenicity tests in field microplots, M. cannonballus caused vine collapse and severe root rot of cantaloupe, reducing root length density by 93%. California isolates of R. vagum and A. cucurbitacearum, although only weakly pathogenic in field microplots, caused root discoloration and reduced vine growth in greenhouse tests. Reduction in dry weight of greenhouse-grown cantaloupe was 40, 23, and 39% for R. vagum, A. cucurbitacearum, and M. cannonballus, respectively.

Effects of Soil Solarization and Fumigation on Root Rot of Melon Caused by Phomopsis sclerotioides and on Soil Microbial Community

Effects of Soil Solarization and Fumigation on Root Rot of Melon Caused by Phomopsis sclerotioides and on Soil Microbial Community

Control of Black Root Rot of Melon by Solarization and Chemicals

Control of Black Root Rot of Melon by Solarization and Chemicals

Chemical Control of Wilt and Root Rot of Melon

Chemical Control of Wilt and Root Rot of Melon

Outbreak of Melon Root Rot Caused by Monosporascus cannonballus in Miyagi Prefecture

Outbreak of Melon Root Rot Caused by <I>Monosporascus cannonballus</I> in Miyagi Prefecture

Root Rot of Melon Caused by Nodulisporium melonis in Japan. 1. Occurrence, Symptoms, Isolation and Pathogenicity.

Collapse of melon with brown-rotted and corky roots occurred in Shizuoka Prefecture, Japan in 1975. This disease was named root rot of melon by Sato et al. in 1976. Nodulisporium melonis Watanabe & Sato (1995) was predominantly isolated from rotted root tissues together with five other fungus genera. In inoculation tests, N. melonis was pathogenic to melon seedlings, but other fungal isolates were not pathogenic. Melon and five other cucurbitaceous crops tested were diseased by growing in the artificially infested soil with N. melonis, but healthy in uninfested soils. This fungus was not pathogenic to wax gourd, and other 18 crops inoculated.

Occurrence of Wilt and Root Rot of Melon in Ibaraki Prefecture

Occurrence of Wilt and Root Rot of Melon in Ibaraki Prefecture

Root Rot of Melon Caused by Nodulisporium melonis in Japan. 2. Idintification.

Nodulisporium melonis sp. nov., the causal fungus of root rot of melon in Japan is described and illustrated. Colonies of this fungus on PDA are white and homogeneous, subhyaline, cream to pale brown in reverse. The conidiophores are erect, hyaline, simple or branched verticillately or irregularly, 45-280×1.2-2.3μm, bearing single conidia or apical spore masses, 2-9 conidia per head on apical fertile portions, denticulate after detachment of conidia, often proliferated from conidia on conidiophores. Conidia are single, in short chains or aggregated, sympodulosporous, acropleurogenous, hyaline, 1-celled, obovoid, cylindrical, elliptical or irregular in shape, 2.5-13.8×1.2-3.0μm (5.9×2.5μm) with basal frill or cylindrical appendix, 3.0-10.0×0.4-1.0μm.

Monosporascus cannonballus . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Monosporascus cannonballus . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Cumumis melo , C. sativus ,? Medicago saliva, Trifolium pratense . DISEASE: Root rot of melon. GEOGRAPHICAL DISTRIBUTION: India, Japan, USA (Arizona).

Monosporascus eutypoides . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Monosporascus eutypoides . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Achyranthes aspera, Citrullus vulgaris, Cucumis melo, Sesamum indicum, Triticum sp. DISEASE: Root rot of melon and watermelons. GEOGRAPHICAL DISTRIBUTION: India, Israel, Libya, Pakistan.