scholarly journals First Report of Sudden Death Syndrome of Soybean in Delaware and Eastern Shore of Maryland

Plant Disease ◽  
2002 ◽  
Vol 86 (6) ◽  
pp. 696-696 ◽  
Author(s):  
R. P. Mulrooney ◽  
N. Fisher Gregory ◽  
S. D. Walker ◽  
A.-M. Webster
Keyword(s):  
Sudden Death ◽  
Sudden Death Syndrome ◽  
Spore Morphology ◽  
Eastern Shore ◽  
Koch’S Postulates ◽  
First Report ◽  
Soil Line ◽  
Foliar Symptoms ◽  
Stem Lesions ◽  
Koch's Postulates

In August and September of 2000, soybean (Glycine max (L.) Merr.) plants from two fields in Sussex County, Delaware, and one field from Somerset County on the eastern shore of Maryland exhibited typical symptoms of sudden death syndrome. The season had been wetter and cooler than normal. Leaf symptoms ranged from small chlorotic spots to elongated regions of interveinal necrosis. Leaflets dropped leaving attached petioles in the upper canopy. Severely infected plants were easily pulled from the soil and had taproots with blue sporodochia, necrotic cortical tissue, and necrosis of secondary roots (2). Initial isolations from the infected plants were made from the basal stems, discolored taproots, vascular tissue, and directly from blue sporodochia. Sections were plated on water agar (WA) amended with neomycin and streptomycin, WA with antibiotics and chloramphenicol, and acidified potato dextrose agar (PDA). The isolates were slow growing on PDA, often staining agar dark maroon, produced little aerial mycelium, and formed macroconidia in blue sporodochia. The fungus was identified as Fusarium solani (Mart.) Sacc. based on spore morphology. Plugs (5 mm) of the fungus from 14-day-old cultures were placed next to the stem just below the soil line of 14-day-old plants of soybean cvs. Essex and Lee 74. Eighteen plants of each cultivar (three per pot) were inoculated and placed on a greenhouse bench for 43 days at 21°C (±2°C). Six noninoculated control plants were also included. Plants were rated for the presence of stem lesions and foliar symptoms. Of the inoculated plants, 70% had mottling, rugosity, and leaf cupping, 6% had severe interveinal leaf necrosis, and 52% had distinct stem lesions at the soil line. Control plants were symptomless. F. solani was recovered from all symptomatic plants and presumed to be F. solani f. sp. glycines based on spore morphology, color, lack of microconidia, and symptoms (1). A more extensive test was conducted to confirm Koch's postulates. Eleven isolates of F. solani f. sp. glycines were grown as before and used to inoculate Essex soybeans as previously described. Inoculated and control plants were randomized on the greenhouse bench and watered using an individual pot irrigation system. Fifty-six days after inoculation plant height was reduced 12% compared with the noninoculated controls. Lesions produced on the lower stem and taproot of the inoculated plants averaged 4.5 cm long. Most plants had mild foliar symptoms that included mottling, rugosity, and leaf cupping. Only three plants had severe foliage symptoms. F. solani f. sp. glycines was recovered from 56% of inoculated plants, completing Koch's postulates for all 11 isolates. Noninoculated controls were symptomless. Sudden death syndrome was not observed in 2001. Soybean is an important crop in the region; 250,000 ha were harvested in 2000 on the Delmarva Peninsula, which includes the three counties of Delaware, nine eastern shore counties of Maryland, and two counties of Virginia. Sudden death syndrome could be a serious threat to profitable soybean production. To our knowledge, this is the first report of sudden death syndrome from this area and represents the most eastern occurrence of this disease reported in the United States. References: (1) K. W. Roy. Plant Dis. 81:259, 1997. (2) K. W. Roy et al. Plant Dis. 81:1100, 1997.

First Report of Phytophthora ramorum Infecting Grand fir in California

2011 ◽  
Vol 12 (1) ◽  
pp. 37
Author(s):  
Kathleen L. Riley ◽  
Gary A. Chastagner ◽  
Cheryl Blomquist
Keyword(s):  
Phytophthora Ramorum ◽  
Christmas Tree ◽  
Native Range ◽  
Tree Plantation ◽  
Koch’S Postulates ◽  
First Report ◽  
Stem Lesions ◽  
Koch's Postulates

Phytophthora ramorum was detected on grand fir in 2003 and 2005 in a Christmas tree plantation near Los Gatos, CA, in association with infected California bay laurel. Isolates derived from stem lesions were used to inoculate grand fir seedlings in two tests. Isolations from lesions on inoculated plants were positive for P. ramorum in both tests. This work provides the completion of Koch's postulates to establish grand fir as a host of P. ramorum. The potential for grand fir to be infected within its native range is unknown. Accepted for publication 1 February 2011. Published 1 April 2011.

scholarly journals First Report of Koch's Postulates Completion of Sudden Death Syndrome of Soybean in Argentina

Plant Disease ◽  
2003 ◽  
Vol 87 (4) ◽  
pp. 447-447 ◽  
Author(s):  
M. Scandiani ◽  
D. Ruberti ◽  
R. Pioli ◽  
A. Luque ◽  
L. Giorda
Keyword(s):  
Sudden Death ◽  
Fusarium Solani ◽  
Colony Growth ◽  
Positive Control ◽  
Sudden Death Syndrome ◽  
Symptom Development ◽  
Koch’S Postulates ◽  
Interveinal Chlorosis ◽  
Soil Infestation ◽  
Koch's Postulates

Foliage symptoms on soybean resembling those of sudden death syndrome were detected in Argentina during 1991 and 1992 in the Pampas Region and during 1992 and 1993 in the Northwest Region. Isolations were made in 1999, 2000, and 2001 from soybean plants (Glycine max (L.) Merr.) showing these symptoms. Five isolates of fungi obtained from taproot tissue and blue sporulation on taproot exteriors were selected for further evaluation. These isolates were plated on potato dextrose agar supplemented with streptomycin (PDAS). Based on the spore morphology, colony growth rate, morphology and pigmentation on PDAS, and lack of microconidia (1) five isolates were identified as Fusarium solani f. sp. glycines. Soybean cvs. Ripley, Spencer, Pioneer 9492RR, and A6445 RG were inoculated in greenhouse tests with each of the isolates using toothpick and soil infestation methods for a total of six experiments. Isolate 171 provided by J. Rupe (University of Arkansas, Fayetteville) was tested as a positive control. Foliar symptoms typical of sudden death syndrome and similar to those in the field were observed 14 and 25 days, respectively, after inoculations using the toothpick and soil infestation methods. Lesions produced on leaves averaged 3.6 for all five isolates and 4 for the reference strain using a disease severity scale where: 1 = no symptoms; 2 = slight symptom development with mottling and mosaic on leaves (1 to 20% foliage affected); 3 = moderate symptom development with interveinal chlorosis and necrosis on foliage (21 to 50% foliage affected); 4 = heavy symptom development with interveinal chlorosis and necrosis (51 to 80% foliage affected); and 5 = severe interveinal chlorosis and necrosis (81 to 100% foliage affected). Noninoculated controls were symptomless. Differences in virulence were observed among the isolates. Based on disease symptoms in the greenhouse and cultural morphology on PDAS, the isolates were classified as Fusarium solani f. sp. glycines. Isolates recovered from symptomatic plants resembled Fusarium solani f. sp. glycines on PDAS and peptone/p-chloro-nitrobenzene agar amended with streptomycin, confirming Koch's postulates. Fusarium solani f. sp. glycines was recovered from 60% of inoculated plants. Reference: (1) K. W. Roy et al. Plant Dis. 81:1100,1997.

scholarly journals Sporulation of Fusarium solani f. sp. glycines, Causal Agent of Sudden Death Syndrome, on Soybeans in the Midwestern and Southern United States

Plant Disease ◽  
1997 ◽  
Vol 81 (6) ◽  
pp. 566-569 ◽  
Author(s):  
K. W. Roy
Keyword(s):  
Sudden Death ◽  
Fusarium Solani ◽  
Causal Agent ◽  
Sudden Death Syndrome ◽  
Southern United States ◽  
Soil Line ◽  
Foliar Symptoms ◽  
Root Decay ◽  
Soybean Plants ◽  
Dark Blue

Production of macroconidia by the causal agent of sudden death syndrome, Fusarium solani f. sp. glycines, occurred on lower stems and roots of soybean plants symptomatic for the disease in Illinois, Indiana, Kentucky, Mississippi, and Tennessee. Most of the sporulation was light to dark blue to blue-green in color. Microscopically (15×) visible sporulation occurred on plants in 26, and macroscopically visible sporulation occurred on plants in 15, of 32 fields inspected. In some fields, the incidence of plants with microscopically visible sporulation was as high as 70%, and the incidence of plants with macroscopically visible sporulation reached 50%. Sporulation varied from pinpoint microscopic areas to macroscopically visible masses 4 to 6 cm2 or larger. Areas of microscopically visible sporulation occurred on lower stems and roots within 2.5 cm above and below the soil line on about 50% of the plants, and areas of macroscopically visible sporulation occurred within the same region on about 60% of the plants. Both microscopic and macroscopic sporulation also occurred on taproots as far as 10 cm or more below the soil line. Severe foliar symptoms and root decay were associated with a greater incidence of plants with sporulation. The occurrence of sporulation should help distinguish sudden death syndrome from other diseases of like foliar symptomatology and help confirm its diagnosis. It is presumed from the results that sporulation eventually contributes to the inoculum density of F. solani f. sp. glycines in soybean fields.

scholarly journals First Report and Confirmed Distribution of Soybean Sudden Death Syndrome Caused by Fusarium virguliforme in Southern Michigan

Plant Disease ◽  
2010 ◽  
Vol 94 (9) ◽  
pp. 1164-1164 ◽  
Author(s):  
M. I. Chilvers ◽  
D. E. Brown-Rytlewski
Keyword(s):  
Sudden Death ◽  
Root Rot ◽  
Field Trial ◽  
The United States ◽  
Sudden Death Syndrome ◽  
Fusarium Virguliforme ◽  
Koch’S Postulates ◽  
Interveinal Chlorosis ◽  
Koch's Postulates ◽  
Β Tubulin

Leaf lesions and root rot symptoms typical of soybean sudden death syndrome (SDS) caused by Fusarium virguliforme O'Donnell & T. Aoki were observed in commercial soybeans (Glycine max (L.) Merr.) in southern Michigan. Leaf symptoms ranged from chlorotic spots to severe interveinal chlorosis and necrosis, no foliar pathogens were noted. In 2008, isolates were collected from Berrien and St. Joseph counties. In 2009, isolates were collected from Cass, St. Joseph, Van Buren, Allegan, and Monroe counties. Pieces of roots with root rot symptoms were washed prior to surface disinfestation with 70% ethanol for 30 s and 0.5% NaOCl for 1 min and incubated on water agar (WA) in petri plates amended with 50 μg/ml of chloramphenicol for the production of sporodochia. Alternatively, spores were collected directly from nondisinfested roots expressing blue sporodochia. Single-spore cultures were derived by streaking macroconidia with a bacterial loop onto 3% WA + chloramphenicol and incubated overnight. With a dissecting microscope, single germinated macroconidia were collected with a sterile 0.2-mm-diameter insect pin and transferred to potato dextrose agar (PDA). Cultures on PDA grew slowly and developed blue-to-purple masses of sporodochia typical of F. virguliforme descriptions and similar to a representative isolate, Mont-1, grown alongside (1,2). Size of macroconidia from the six representative isolates, one from each county (including isolates derived from surface-disinfested and nondisinfested roots), and Mont-1 were determined to be within the range for F. virguliforme (42 to 56 × 5 to 6 μm), with an average of four septa per macroconidia. Identity of the representative isolates was confirmed by partial DNA sequencing of both strands of the internal transcribed spacer (ITS) region of the ribosomal RNA gene, translation elongation factor 1-α, and β-tubulin loci. All six representative isolates were identical in each of the three loci and matched with 100% similarity F. virguliforme accessions in GenBank and Fusarium-ID database searches, except for the β-tubulin locus in which a single nucleotide insertion was noted (Accession Nos. HM453328–HM453330). Sequences were 98 to 99% similar to other SDS Fusarium spp. not yet recorded in the United States. Koch's postulates were performed in the greenhouse according to Malvick and Bussey (3). Infested sorghum seed (~20 g) was placed 2 cm below soybean seed of susceptible cv. Williams 82 in plastic pots. Noninfested sorghum seed was used as a negative control and sorghum infested with Mont-1 as a positive control. Chlorotic spots developed 2 weeks after establishing the trial, and 3 to 4 weeks postinoculation, severe SDS symptoms of foliar interveinal chlorosis and necrosis and severe root rot developed. Koch's postulates were completed by reisolating F. virguliforme from a subset of infected plants. In addition, an isolate of F. virguliforme collected in 2008 was used to inoculate a 2009 field trial in East Lansing, MI with no history of SDS. Typical SDS symptoms developed in the field trial and F. virguliforme was isolated from a symptomatic plant that was identified as described above. Despite being reported across the majority of soybean-producing states, to our knowledge, this is the first confirmation and distribution report for SDS in Michigan. References: (1) T. Aoki et al. Mycoscience 46:162, 2005. (2) G. L. Hartman et al. Plant Dis. 81:515, 1997. (3) D. K. Malvick and K. E. Bussey. Can. J. Plant Pathol. 30:467, 2008.

First Report of Pathogenicity of Fusarium sporotrichioides and Fusarium acuminatum on Sunflowers in the United States

2010 ◽  
Vol 11 (1) ◽  
pp. 42 ◽  
Author(s):  
F. Mathew ◽  
B. Kirkeide ◽  
T. Gulya ◽  
S. Markell
Keyword(s):  
United States ◽  
Helianthus Annuus ◽  
The United States ◽  
Fusarium Sporotrichioides ◽  
Charcoal Rot ◽  
Koch’S Postulates ◽  
First Report ◽  
Fusarium Acuminatum ◽  
Helianthus Annuus L ◽  
Koch's Postulates

Widespread infection of charcoal rot was observed in a commercial sunflower field in Minnesota in September 2009. Based on morphology, isolates were identified as F. sporotrichioides and F. acuminatum. Koch's postulates demonstrated pathogencity of both species. To our knowledge, this is the first report of F. sporotrichoides and F. acuminatum causing disease on Helianthus annuus L. in the United States. Accepted for publication 23 August 2010. Published 15 September 2010.

scholarly journals First Report of Stemphylium botryosum Causing Leaf Blight of Kiwi in the Province Imathia, Northern Greece

Plant Disease ◽  
2008 ◽  
Vol 92 (4) ◽  
pp. 650-650 ◽  
Author(s):  
T. Thomidis ◽  
T. J. Michailides
Keyword(s):  
Apical Cell ◽  
Morphological Characteristics ◽  
Leaf Blight ◽  
Width Ratio ◽  
Northern Greece ◽  
Cell Width ◽  
Koch’S Postulates ◽  
First Report ◽  
Stemphylium Botryosum ◽  
Koch's Postulates

In Greece, kiwi (Actinidia deliciosa) is mostly found in the northern part of the country where approximately 440,000 ha are grown. In the summer of 2006, a Stemphylium sp. was frequently isolated from leaves of kiwi (cv. Hayward) grown in the province of Imathia. Symptomatic leaves were covered with irregular, necrotic, brown areas. Lesions had a distinct margin that, in some cases, covered a wide part of the diseased leaves. Intense symptoms were frequently observed and associated with defoliation. This Stemphylium sp. was consistently isolated from diseased leaves onto potato dextrose agar (PDA) after surface sterilization with 0.1% chlorine solution. On the basis of morphological characteristics of mycelia, dimensions (length 20 to 29 μm and width 14 to 21 μm) and mean length/width ratio (1.42 μm) of conidia, and width and apical cell width of condiophores, the fungus was identified as Stemphylium botryosum (Wallr.) (2,3) Koch's postulates were completed in the laboratory by inoculating leaves of kiwi (cv. Hayward) with an isolate of S. botryosum originated from a symptomatic leaf of a Hayward kiwi. Twenty leaves were surface sterilized by dipping them into 0.1% chlorine solution for 2 to 3 min, washing in sterile distilled water, and allowing them to dry in a laminar flow hood. A leaf was then placed into a petri plate containing a wet, sterilized paper towel. Inoculation was made by transferring a 5-mm-diameter mycelial disc from the margins of a 7-day-old culture onto the center of each leaf surface. Petri plates were closed and incubated at 25°C with 12 h of light for 6 days. Koch's postulates were satisfied when the same S. botryosum was reisolated from 100% of inoculated leaves that developed symptoms similar to those observed in the vineyards. Leaves inoculated with a PDA plug alone (with no S. botryosum) did not develop any symptoms. Previously, Alternaria alternata was reported as the causal agent of a leaf spot pathogen of kiwi (1,4). To our knowledge, this is the first report of the occurrence of S. botryosum causing leaf blight of kiwi in Greece and worldwide. This pathogen can cause a high level of defoliation in diseased plants. References: (1) L. Corazza et al. Plant Dis. 83:487, 1999. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Mycology Institute. London, England, 1971. (3) E. G. Simmons. Mycologia 61:1, 1969. (4) C. Tsahouridou and C. C. Thanassoulopoulos. Plant Dis. 84:371, 2000

scholarly journals First report of Pestalotiopsis diospyri causing canker on persimmon trees

2011 ◽  
Vol 33 (3) ◽  
pp. 1019-1022 ◽  
Author(s):  
Giselda Alves ◽  
Francineia Silva Verbiski ◽  
Themis J. Michaelides ◽  
Louise Larissa May-de Mio
Keyword(s):  
Diospyros Kaki ◽  
Southern Brazil ◽  
Severe Damage ◽  
Santa Catarina ◽  
Koch’S Postulates ◽  
Canker Disease ◽  
First Report ◽  
Koch's Postulates

During 2006 to 2009 season symptoms of a canker disease were observed on twigs and branches of young and mature persimmon trees (Diospyros kaki L.) cv. Fuyu in the States of Santa Catarina and Paraná in the Southern Brazil. The cankers result in severe damage and reduced production. Isolations from the margins of these cankers revealed a genus of Pestalotiopsis. Koch's postulates were confirmed using two isolates of the pathogen which was identified as Pestalotiopsis diospyri.

scholarly journals Field Response of Glyphosate-Tolerant Soybean to Herbicides and Sudden Death Syndrome

Plant Disease ◽  
2001 ◽  
Vol 85 (7) ◽  
pp. 773-779 ◽  
Author(s):  
S. Sanogo ◽  
X. B. Yang ◽  
P. Lundeen
Keyword(s):  
Sudden Death ◽  
Field Experiments ◽  
Foliar Application ◽  
The United States ◽  
Sudden Death Syndrome ◽  
North Central ◽  
The North ◽  
Foliar Symptoms ◽  
Field Response ◽  
Soybean Plants

Three-year field experiments were conducted to assess the development of sudden death syndrome (caused by Fusarium solani f. sp. glycines) in three soybean cultivars, tolerant (P9344 and A3071) and nontolerant (BSR101), to glyphosate following foliar application of four herbicides (acifluorfen, glyphosate, imazethapyr, and lactofen) commonly applied to soybeans in the north-central region of the United States. Cultivar A3071 is resistant to sudden death syndrome, whereas cultivars P9344 and BSR101 are susceptible to this disease. There was no statistically significant cultivar-herbicide interaction with respect to the severity of foliar symptoms of the disease and the frequency of isolation of F. solani f. sp. glycines from roots of soybean plants. Across all herbicide treatments, the level of sudden death syndrome was lower in the disease-resistant cultivar than in the susceptible ones. There was an increase in the disease levels under application of acifluorfen, glyphosate, and imazethapyr compared with nontreated or lactofen-treated plants. The results obtained indicate that the response of glyphosate-tolerant soybeans to sudden death syndrome is not different from the response of conventional soybeans to this disease following application of the selected herbicides, and the resistance of soybean to sudden death syndrome was not changed with application of glyphosate.

Red Crown Rot of Hop in Oregon Caused by Phomopsis tuberivora

2013 ◽  
Vol 14 (1) ◽  
pp. 52
Author(s):  
David H. Gent ◽  
George Mueller-Warrant ◽  
Joanna L. Woods ◽  
Melodie L. Putnam ◽  
Megan C. Twomey
Keyword(s):  
Crown Rot ◽  
Management Implications ◽  
Koch’S Postulates ◽  
First Report ◽  
Red Crown Rot ◽  
Weak Growth ◽  
Koch's Postulates

During July 2007, symptoms including weak growth and death of plants of cultivar Fuggle were reported by a hop grower in Marion Co., OR. Phomopsis tuberivora H.T. Güssow & W.R. Foster 1932 was consistently recovered from affected plants. Koch's postulates were fulfilled with three isolates of the fungus, establishing the pathogen and the disease red crown rot as the cause of the damage. This is the first report of red crown rot on hop in Oregon, which may have important management implications for affected hop yards and farms. Accepted for publication 19 March 2013. Published 24 June 2013.

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