scholarly journals Morphological and pathogenic characteristics of the fungus Cladobotryum dendroides, the causal agent of cobweb disease of the cultivated mushroom Agaricus bisporus in Serbia

2008 ◽  
Vol 23 (3) ◽  
pp. 175-181 ◽  
Author(s):  
Ivana Potocnik ◽  
Emil Rekanovic ◽  
Svetlana Milijasevic ◽  
Biljana Todorovic ◽  
Milos Stepanovic
Keyword(s):  
Agaricus Bisporus ◽  
Natural Infection ◽  
Morphological Characteristics ◽  
Causal Agent ◽  
Fruiting Bodies ◽  
Cultivated Mushroom ◽  
Pathogenicity Tests ◽  
Agar Media ◽  
Cobweb Disease

Twenty isolates were isolated from diseased fruiting bodies of Agaricus bisporus collected from Serbian mushroom farms during 2003-2007. The isolates formed white, cottony, aerial colonies on agar media. With age, conidia and colonies turned yellow and redish. Pathogenicity of these isolates was confirmed by inoculation of harvested basidiomes of A. bisporus and by casing inoculation. Symptoms similar to natural infection were recorded. Based on pathogenicity tests and morphological characteristics, the isolates were identified as Cladobotryum dendroides (Bulliard : Fries) W. Gams & Hoozemans.

Three Mycogone species, including a new species, cause wet bubble disease of Agaricus bisporus in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yixin Du ◽  
Niuniu Shi ◽  
Hongchun Ruan ◽  
Furu Chen
Keyword(s):  
New Species ◽  
Agaricus Bisporus ◽  
Phylogenetic Analyses ◽  
Morphological Characteristics ◽  
Edible Mushroom ◽  
Fruiting Bodies ◽  
Button Mushroom ◽  
Pathogenicity Tests ◽  
Prevalent Species ◽  
A New Species

White button mushroom, Agaricus bisporus (Lange) Imbach, is the most extensively cultivated and edible mushroom worldwide. The production of A. bisporus is commonly affected by wet bubble disease (WBD) imposing a significant economic burden in China. Although studies have shown that this disease is caused by fungi of Mycogone genus, the pathogen has not been fully characterized. In this study, 802 samples of diseased fruiting bodies of A. bisporus were collected from nine major mushroom-cultivating provinces in China, yielding a total of 586 Mycogone isolates. The morphological characteristics of these isolates were observed and compared, and multi-locus phylogenetic analyses (ITS, ACT, TEF1-α, TUB, RPB2, and LSU) were performed on the selected representative isolates. Three Mycogone species were identified: a new species M. xinjiangensis, M. perniciosa, and M. rosea. Mycogone rosea was the first-ever reported in China. Furthermore, M. rosea was found to be the most prevalent species (54.95% of all isolates) in all the sampled areas, except in Hubei and Xinjiang, followed by M. perniciosa (39.93%) and M. xinjiangensis (5.12%). Pathogenicity tests on the fruiting body and mushroom bed substantiated Koch’s postulates developing mildly different symptoms after inoculation with each species. This study, therefore, enhances our knowledge of the species associated with WBD in A. bisporus and provides useful insights for preventing WBD and allied diseases.

scholarly journals First Report of Cobweb Disease Caused by Cladobotryum mycophilum on the Edible Mushroom Pleurotus eryngii in Korea

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1374-1374 ◽  
Author(s):  
M. K. Kim ◽  
Y. H. Lee ◽  
K. M. Cho ◽  
J. Y. Lee
Keyword(s):  
Fungal Pathogen ◽  
Natural Infection ◽  
Morphological Characteristics ◽  
Edible Mushroom ◽  
Pleurotus Eryngii ◽  
Pathogenicity Test ◽  
Distilled Water ◽  
First Report ◽  
Cobweb Disease ◽  
Fungal Mycelia

Pleurotus eryngii is one of the most commercially important mushrooms in Korea. In May 2009, unusual symptoms were observed in P. eryngii grown in mushroom farms in Changnyeong and Hapcheon, in Gyeong-nam Province, Korea. One of the main symptoms was cobweb-like growth of fungal mycelia over the mushroom surface. Colonies on the surface rapidly overwhelmed the mushrooms, which turned pale brown or yellow. Mushrooms eventually turned dark brown and became rotten. Colonies of the isolates on potato dextrose agar (PDA) were yellowish, and a reddish or orange color was evident in the agar. The colonies grew 20 to 30 mm per day on PDA. Large spores with a single septum were produced on vertically branched conidiophores bearing two to four, mostly three to four, sporogenous cells, ranging from 17.2 to 20.5 μm long and 8.0 to 10.2 μm thick. The shape of the conidia was ellipsoid and obovoid. These morphological characteristics are consistent with descriptions of Cladobotryum mycophilum, a causal agent of cobweb disease in Agaricus bisporus (1,4). To identify the isolated fungal pathogen, the ITS region was amplified with ITS1 and ITS4 primers and sequenced. The sequence data from the isolate was deposited in GenBank (Accession No. JF693809). A BLAST search showed that the isolated strain belonged to a species of Cladobotryum. The highest similarity (99.5%) was to the ITS sequence of C. mycophilum (teleomorph Hypomyces odoratus) (GenBank Accession Nos. JF505112 and Y17096) (3,4). The strain that was tested for pathogenicity was grown on PDA at 25°C for 72 h. The inoculum was prepared by flooding the agar surface with 10 ml of sterilized double distilled water and scraping it with a spatula. The resulting spore suspension was filtered through three layers of cheesecloth. Conidial concentration was adjusted with a hemacytometer to 1 × 106 conidia ml–1. A conidia suspension was inoculated onto each of several stages of mushroom cultivation with a pipette. The control was spotted with double distilled water. In the case of infection during the inoculation and spawn running stages, the fungal mycelia colonized the media and hampered development of the mycelium of P. eryngii. In the regeneration and primordia formation stages of the host, the mycelium of the pathogen covered the surface of the plastic bottle containing the substrates and developed many spores. In the growing and harvesting stages, the surface of mushroom was overwhelmed by the mycelium of the fungal pathogen and turned pale or dark brown, accompanied by cracking of the stipe surface and finally rotting with a foul odor. These symptoms were similar to the observation from natural infection. The symptoms of the cobweb-like disease in A. bisporus (1,2) were observed within 5 to 7 days of inoculation with conidia suspensions of C. mycophilum. Fungi isolated from inoculated mushrooms were shown to be identical, based on phenotypic characteristic, to the inoculated strain used in these pathogenicity tests. No symptoms were observed on controls. To our knowledge, this is the first report on the occurrence of C. mycophilum on the edible mushroom P. eryngii in Korea. Based on the pathogenicity test results, the pathogen could attack P. eryngii in any cultivation stage, making it a potentially serious fungal pathogen in P. eryngii. References: (1) C. G. Back et al. J. Gen. Plant Pathol. 76:232, 2010. (2) R. H. Gaze. Mushroom J. 546:23, 1995. (3) F. J. Gea et al. Plant Dis. 95:1030, 2011. (4) H. M. Grogan and R. H. Gaze. Mycol. Res. 104:357, 2000.

scholarly journals Macadamia Quick Decline Caused by Phytophthora tropicalis is Associated with Sap Bleeding, Frass, and Nectria in Hawaii

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 128-128 ◽  
Author(s):  
L. Keith ◽  
L. Sugiyama ◽  
M. Nagao
Keyword(s):  
Disease Incidence ◽  
Morphological Characteristics ◽  
Signs And Symptoms ◽  
Causal Agent ◽  
Tree Canopy ◽  
Internal Transcribed Spacers ◽  
Morphological Identification ◽  
Fruiting Bodies ◽  
Ambrosia Beetles ◽  
Persistent Problem

Macadamia quick decline (MQD) has been a persistent problem since 1986 when it started killing productive 14- to 36-year-old macadamia trees in the Hilo, HI area. Fungi including Nectria regulosa, Xylaria arbuscula, Phellinus gilvus, and Acremonium recifei have been attributed to MQD and could kill twigs on healthy macadamia trees after artificial inoculation (3). The oomycete originally called Phytophthora capsici and later reclassified as P. tropicalis was also considered to be involved in the MQD complex (3). However, the primary causal agent has never been determined and the issue continues to perplex the industry. Between 2005 and 2006, a mature macadamia field on the Waiakea Experiment Station planted with cv. HAES 333 began to experience a high frequency of MQD. Trees exhibiting dull green, yellow, or brown leaves within the tree canopy were observed. Sap bleeding from the trunk, Ambrosia beetles, and Nectria fruiting bodies were consistently associated with MQD. Disease incidence was 22%. Of 21 infected trees, 53% died within an average period of 6.8 months. Four branch samples were collected from four trees showing browning of leaves, sap bleeding, Ambrosia beetles, and Nectria, and seven P. tropicalis isolates were recovered from diseased tissue on water agar or V8 agar media. No other microorganisms were isolated from diseased branches. On the basis of the morphological characteristics described by Aragaki and Uchida (1), the isolates were identified as P. tropicalis. The morphological identification was confirmed by molecular analysis of the 5.8S subunit and flanking internal transcribed spacers (ITS1 and ITS2) of rDNA amplified from DNA extracted from single-zoospore cultures with the ITS1/ITS4 primers (2,4) and sequenced (GenBank No. FJ849839). Pathogenicity tests were conducted on four 12-year-old macadamia trees in the field. A 4 × 104 zoospore/ml suspension of P. tropicalis isolate L1 was injected into branches of cv. HAES 344 to incite MQD signs and symptoms. Branches inoculated with P. tropicalis started showing the initial sign of MQD, excessive sap bleeding, within 36 days postinoculation (dpi). The presence of Ambrosia beetle frass and the appearance of orange fruiting bodies of Nectria were visible within 110 dpi. No symptoms were noted on the four control tree branches inoculated by the same method but with sterilized distilled water. P. tropicalis was reisolated from the symptomatic macadamia branches, fulfilling Koch's postulates. To our knowledge, this is the first report of P. tropicalis as the primary causal agent of MQD and its association with sap bleeding, Ambrosia beetles, and a saprotrophic species of Nectria. After completion of our research, Ko (3) reported that the MQD P. capsici was P. tropicalis, supporting our finding in this study. Quick decline of macadamia trees continues to be a serious problem in Hawaii. Minimizing tree loss in mature orchards is critical for maintaining the economic viability of Hawaii's macadamia industry. Understanding the biology of this pathosystem will enable the development of control and prevention strategies. References: (1) M. Aragaki and J. Y. Uchida. Mycologia 93:137, 2001. (2) G. Caetano-Annolles et al. Curr. Genet. 39:346, 2001. (3) W.-H. Ko. Bot. Stud. 50:1, 2009. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

scholarly journals First Report of Cobweb Disease in Oudemansiella raphanipes Caused by Cladobotryum varium in Beijing, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Wentao Qin ◽  
Jun Li ◽  
Zhaoqing Zeng ◽  
Shouxian Wang ◽  
Lin Gao ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Morphological Characteristics ◽  
Spore Suspension ◽  
Integrated Analysis ◽  
Yield Reduction ◽  
Pathogenicity Test ◽  
Fruiting Bodies ◽  
First Report ◽  
Cobweb Disease ◽  
Beijing China

Oudemansiella raphanipes is an edible mushroom with medicinal properties,which has been recently cultivated throughout China (Hao et al. 2016). In October 2019, a disease with symptoms similar to that of cobweb disease (Carrasco et al. 2017) was observed in O. raphanipes in the Tongzhou District, Beijing, China, infecting 25% of the fruiting bodies (Fig. 1A, B). White cotton-like net of hyphae were present typically on the casing soil or on the stipe of the fruiting bodies; they gradually spread to the pileus, covering the fruiting body, which eventually wilted and died (Fig. 1C, D), resulting in yield reduction and economic loss. Cultures were obtained by aseptically transferring the diseased fruiting bodies onto potato dextrose agar (PDA) at 25 °C; they were deposited in the culture collection (ID: JZBQA1) of the Beijing Academy of Agricultural and Forestry Sciences, China. The colonies were pale white/white, with an occasional formation of yellow diffusing pigments on the reverse side (Fig. 1E–G). Conidiophores were Cladobotryum-like, phialides were solitary or commonly divergent in whorls of 2–3 (–4), lageniform to subulate, 20–63.5 (–66) × (3.8–) 4–5.3 (–9) μm (n = 40) (Fig. 1H, I); conidia were hyaline, oval to ellipsoidal, with one or two septa, (10.4–) 11.4–20 (–22) × 6.6–9.5 (–10) μm (n = 40) (Fig. 1J); chlamydospores were globose or ellipsoidal (Fig. 1K). The morphological characteristics were consistent with that of Cladobotryum varium (Back et al. 2012a, b; Sun et al. 2019). For species-level fungal identification, genomic DNA was extracted using the DNeasy Plant Mini Kit (Qiagen, USA). The internal transcribed spacer (ITS) regions, translation elongation factor 1 alpha exon (TEF1-α), RNA polymerase II subunit b (RPB2), and RNA polymerase I largest subunit (RPB1) genes were amplified using the primer pairs ITS1/ITS4 (White et al. 1990), EF1-983F/2218R (Rehner and Buckley 2005), RPB2-5F/7cR (Liu et al. 1999), and RPB1F1 (5'-GCCGATGAAGTTGGTCTA-3')/RPB1R1 (5'-TATGTTGCGGTGAGCCTT-3'), respectively. A BLAST nucleotide search showed 99.34% (449/452 bp), 99.24% (914/921 bp), 98.08% (1,022/1,042 bp), and 99.66% (588/590 bp) homology, respectively, with those of the ex-type culture of Hypomyces aurantius TFC 95-171 (FN859425.1, FN868743.1, FN868679.1, and FN868805.1). The four sequences were deposited in GenBank (accession numbers: MW534093, MW560066, MW560064, and MW560065). Phylogenetic trees based on the assessed gene loci revealed that the JZBQA1 strain was closely related to C. varium (Fig. 2). A in vivo pathogenicity test was performed using the fruiting bodies (Fig. 1L, O). Spore suspension (108 spores/mL) of the JZBQA1 strain or sterile distilled water was sprayed on six healthy fruiting bodies, maintained in an artificial climate chamber at 24-26°C. Cobweb-like features were observed on the fruiting bodies treated with the spore suspension 2-3 days post-inoculation; while those treated with water did not exhibit such features (Fig. 1L, O). The same pathogen was re-isolated and confirmed from the infected fruiting bodies by integrated analysis of morphological characteristics and gene sequencing data. Cladobotryum spp. infects different varieties of cultivated edible mushrooms, resulting in the development of cobweb diseases (Cao et al. 2020; Carrasco et al. 2017). Cladobotryum varium is the causal agent of cobweb disease in Flammulina velutipes and Hypsizygus marmoreus (Back et al. 2012a, b). To our knowledge, this is the first report of cobweb disease caused by C. varium in O. raphanipes. This finding is a valuable contribution to the knowledge of cobweb disease development in edible fungi.

scholarly journals Identification and control of Cladobotryum spp., causal agents of cobeweb disease of cultivated mushroom

2009 ◽  
Vol 24 (3) ◽  
pp. 165-175
Author(s):  
Ivana Potocnik
Keyword(s):  
Disease Control ◽  
Agaricus Bisporus ◽  
Alternative Methods ◽  
Mushroom Cultivation ◽  
Disease Symptoms ◽  
Resistance Evolution ◽  
Cultivated Mushroom ◽  
Cobweb Disease ◽  
And Control ◽  
Surface Covering

Cladobotryum spp. are causal agents of cobweb disease, one of the most serious diseases of cultivated mushroom (Agaricus bisporus (Lange) Imbach) in Serbia and worldwide, which affects product quality and yield. The disease symptoms are: cottony fluffy white or yellowish to pink colonies on mushroom casing, rapid colonization of casing surface, covering of host basidiomata by mycelia, and their decay. Prochloraz-Mn has been officially recommended for mushroom cultivation in EU countries. However, inefficiency of prochloraz-Mn has been noted at a level of spotting symptoms of cobweb disease. With regard to cases of resistance evolution and a general threat to the environment and human health, special attention should be focused on good programmes of hygiene, and inventing and developing alternative methods of disease control.

scholarly journals First Report of Cobweb on White Button Mushroom (Agaricus bisporus) in Spain Caused by Cladobotryum mycophilum

Plant Disease ◽  
2012 ◽  
Vol 96 (7) ◽  
pp. 1067-1067 ◽  
Author(s):  
F. J. Gea ◽  
M. J. Navarro ◽  
J. Carrasco ◽  
A. J. González ◽  
L. M. Suz
Keyword(s):  
Agaricus Bisporus ◽  
Causal Agent ◽  
Control Treatment ◽  
Parasitic Fungus ◽  
Conidial Suspension ◽  
Fruiting Bodies ◽  
Button Mushroom ◽  
First Report ◽  
White Button Mushroom ◽  
La Mancha

Between 2008 and 2011, symptoms of cobweb were observed in commercial white button mushroom (Agaricus bisporus) crops in Castilla-La Mancha (Spain). Typical symptoms started as white, cobweb-like mycelial growth over the surface of the casing soils and fruiting bodies. Later, the mycelium changed to a grayish white, dense powder and the affected fruiting bodies turned pale yellow or reddish brown before rotting. Two types of cap spotting were observed, dark brown spots with a poorly defined edge and light brown spots. The first symptoms were commonly seen in the second or third break (flush) of mushrooms. Infected tissues of A. bisporus were plated onto potato dextrose agar (PDA) and a parasitic fungus was isolated. Fungal colonies consisted of abundant, cottony, aerial mycelium spreading rapidly over the PDA, and red pigment spreading into the agar. The cultures lacked a camphor odor. Conidiogenous cells were 24 to 45 μm long, 3 to 6 μm wide basally, and tapered slightly to the tip. Conidia were cylindrical to narrowly ellipsoidal, 15 to 28 × 8 to 11 μm, and zero- to three-septate. Total DNA was extracted and the internal transcribed spacer (ITS) region of rDNA amplified for one mycelial isolate using ITS1F/ITS4 primers (2,4). The amplicon was sequenced (GenBank Accession No. JQ004732). BLAST analysis showed highest similarity (99 and 100%) of the ITS sequence to four ITS sequences of Cladobotryum mycophilum (teleomorph Hypomyces odoratus) (GenBank Accession Nos. AB527074, JF505112, Y17095, and Y17096) (1,3) among other sequences of the same species. Two pathogenicity trials (A and B) were performed in mushroom-growing rooms, with 24 blocks in each assay containing pasteurized, spawned, and incubated A. bisporus substrate (10 kg, 0.15 m2). The blocks were cased with a 35-mm layer of a peat-based casing soil (5.5 liter/block). Nine days after casing, a conidial suspension (7.5 × 103 conidia/ml) of one isolate of C. mycophilum was sprayed (20 ml/block) onto the surface of the casing layer of 12 blocks at 106 conidia/m2. Twelve blocks were sprayed with sterile distilled water as a control treatment. Blocks were maintained at 17.5°C and 90% relative humidity. The first cobweb symptoms developed 25 days after inoculation, between the second and third breaks in trial A; and after 11 days, between the first and second breaks in trial B. C. mycophilum was consistently reisolated from eight inoculated blocks (67%) in trial A, and 11 inoculated blocks (92%) in trial B. The total area of the crop affected by cobweb was 30% in inoculated blocks in trial A and 45% in trial B. The noninoculated blocks remained healthy. Compared with the noninoculated control blocks, a 10.7% decrease in yield of mushrooms was observed in trial A and 9.1% in trial B. Previously, C. dendroides was the only known causal agent of cobweb in Spain. To our knowledge, this is the first report of C. mycophilum causing cobweb in white button mushroom in Spain, although the disease and causal agent were previously reported on cultivated king oyster mushroom (Pleurotus eryngii) in Spain (3). References: (3) C.-G. Back et al. J. Gen. Plant Pathol. 76:232, 2010. (1) M. Gardes and T. D. Bruns. Mol. Ecol. 2:113, 1993. (4) F. J. Gea et al. Plant Dis. 95:1030, 2011. (2) T. J. White et al. PCR Protocols. A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

scholarly journals A large-scale study on the effectiveness of a Bacillus subtilis Ch-13-based biofungicide against green mould disease and mushroom yield improvement

2021 ◽  
Vol 36 (2) ◽  
pp. 83-90
Author(s):  
Ivana Potocnik ◽  
Biljana Todorovic ◽  
Svetlana Milijasevic-Marcic ◽  
Jelena Lukovic ◽  
Gabriella Kanizai-Saric ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Untreated Control ◽  
Agaricus Bisporus ◽  
Large Scale ◽  
Natural Infection ◽  
Subtilis Strain ◽  
Cultivated Mushroom ◽  
Green Mould ◽  
Mushroom Yield ◽  
Final Amount

The aim of this study was to test a biofungicide based on Bacillus subtilis Ch-13 and its effectiveness in the control of green mould disease of cultivated mushroom in comparison with the fungicide prochloraz. Biofungicide effectiveness in disease control and impact on yield were evaluated on Agaricus bisporus after its natural infection with Trichoderma aggressivum in a commercial mushroom growing facility. An assay for testing the microbial efficacy of the biofungicide was conducted in two different procedures involving either three or two split doses. The highest statistically significant effectiveness in green mould control was shown by the fungicide prochloraz (71.43%), followed by the biofungicide applied in tree split doses (53.57%), and finally its two doses (45.46%). The biofungicide significantly improved yield in comparison with an untreated control and the fungicide prochloraz. Three split applications of B. subtilis strain Ch-13 enhanced mushroom yield to a larger extent than its two split doses, although the same final amount was used in both procedures. Biofungicide application in three split doses increased the total mass of harvested mushrooms 8.41% compared to the untreated control, and 10.53% compared to the fungicide prochloraz. These results implied that the biofungicide should be applied in three split applications: 30 ml (second day after casing) + 15 ml (two weeks after casing) + 15 ml (after first flush, 20-25 days after casing). The biofungicide B. subtilis Ch-13 should be further investigated regarding its joint usage with chemical fungicides in different application procedures, as it showed remarkable characteristics both in terms of promoting mushroom yield and inhibiting the spread of mycopathogenic T. aggressivum.

scholarly journals Bakanae Disease of Rice in Malaysia and Indonesia: Etiology of the Causal Agent Based on Morphological, Physiological and Pathogenicity Characteristics

2008 ◽  
Vol 48 (4) ◽  
pp. 475-485 ◽  
Author(s):  
Nur Izzati Mohd Zainudin ◽  
Azmi Razak ◽  
Baharuddin Salleh
Keyword(s):  
Disease Incidence ◽  
Morphological Characteristics ◽  
Peninsular Malaysia ◽  
Causal Agent ◽  
Fusarium Fujikuroi ◽  
Bakanae Disease ◽  
Agent Based ◽  
Growing Seasons ◽  
Pathogenicity Tests ◽  
Solvent Systems

Bakanae Disease of Rice in Malaysia and Indonesia: Etiology of the Causal Agent Based on Morphological, Physiological and Pathogenicity CharacteristicsBakanae disease on rice has been recorded almost in all countries where paddy is grown commercially, especially in Asian countries, including Malaysia and Indonesia. Bakanae disease was widespread in Peninsular Malaysia and three provinces of Indonesia with the range of disease severity from scale 1 to 5 and disease incidence from 0.5 to 12.5% during 2004-2005 main growing seasons. A total of fiveFusariumspecies belonging to section Liseola and their allied i.e.Fusarium fujikuroi, F. proliferatum, F. sacchari, F. subglutinans and F. verticillioideswere isolated and identified on the basis of their morphological characteristics. Literature data showed that the bakanae disease of rice all over the world is caused byF. fujikuroiand probably some otherFusariumspecies from section Liseola or allied. However, from pathogenicity tests that have been carried out by using variety MR 211 of rice it was evident thatF. fujikuroiwas highly virulent and the only species involved in causing bakanae disease. Therefore, this species was the only one detected to be able to produce gibberellic acid - (GA3) with Rfvalue 0.40 and 0.62, developed in solvent systems isopropanol:ammonia:water (10: 1: 1), v/v/ v and chloroform:ethyl acetate:formic acid (5: 4: 1), v/v/v, respectively. This knowledge would be invaluable in developing our understanding on the interaction betweenF. fujikuroiand the host plants.

scholarly journals Gladiolus Corm Rot Caused by Sclerotium rolfsii in Argentina

Plant Disease ◽  
2001 ◽  
Vol 85 (12) ◽  
pp. 1285-1285
Author(s):  
M. C. Rivera ◽  
E. R. Wright ◽  
S. Capucchio
Keyword(s):  
Sclerotium Rolfsii ◽  
Potato Dextrose Agar ◽  
Causal Agent ◽  
Pathogenicity Tests ◽  
Agar Media ◽  
Mycelial Strands

In 2000, rot was observed on Gladiolus sp. corms produced and stored in a production locale of the Province of Corrientes, Argentina. Symptoms were associated with the development of whitish mycelial strands and light brown 0.8- to 1.5-mm-diameter globose sclerotia typical of Sclerotium rolfsii Sacc. The fungus was isolated on potato dextrose agar. Pathogenicity tests were done by placing plugs of agar media containing mycelium and sclerotia on corms previously wounded with a scalpel. The corms were planted in sterilized soil, incubated at 20 ± 3°C, and watered frequently. Wilt symptoms were observed 40 days after planting. Basal leaves turned yellow and crown and corm rot developed. Thirty-eight percent of the plants failed to emerge due to corm rot. The pathogen was reisolated from inoculated corms that had become diseased. Control corms, which had been inoculated with sterile agar plugs, did not become diseased. The causal agent of the disease was confirmed as S. rolfsii. To our knowledge, this is the first documentation of gladiolus rot caused by S. rolfsii in Argentina.

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