scholarly journals Identification of Erwinia rhapontici as the Causal Agent of Crown and Shoot Rot and Pink Seed of Pea in Nebraska

2016 ◽  
Vol 17 (3) ◽  
pp. 155-157 ◽  
Author(s):  
Anthony O. Adesemoye ◽  
Hsin-Ho Wei ◽  
Robert M. Harveson
Keyword(s):  
16S Rdna ◽  
Causal Agent ◽  
High Plains ◽  
Emerging Pathogens ◽  
High Incidence ◽  
Disease Survey ◽  
Pathogenicity Tests ◽  
Erwinia Rhapontici ◽  
Central High

Dry yellow pea production has been increasing in the central High Plains. One of the emerging pathogens of pea in the region is Erwinia rhapontici. In a Nebraska disease survey, a pea field exhibited a high incidence of bacterial-like symptoms. Four of the isolates recovered from samples were identified as E. rhapontici by sequencing the 16s rDNA. Similar symptoms to those seen on the field were also reestablished by these strains in pathogenicity tests through rolled towel and greenhouse assays. Accepted for publication 2 June 2016. Published 6 July 2016.

scholarly journals First Report of Aphanomyces Root Rot of Sugar Beet in Nebraska and Wyoming

Plant Disease ◽  
2000 ◽  
Vol 84 (5) ◽  
pp. 596-596 ◽  
Author(s):  
R. M. Harveson
Keyword(s):  
Sugar Beet ◽  
Beta Vulgaris ◽  
Root Rot ◽  
Causal Agent ◽  
High Plains ◽  
Sugar Beets ◽  
Koch’S Postulates ◽  
First Report ◽  
Aphanomyces Cochlioides ◽  
Central High

Sugar beet (Beta vulgaris L.) plants exhibiting dull green and chlorotic foliage were first observed in a field near Dalton, NE, in late July 1999. Root symptoms included distal tip rot with internal, yellow-brown, water-soaked tissues. Isolations on MBV medium (1) consistently yielded Aphanomyces cochlioides Drechs. Water cultures produced primary zoospores that encysted at the tips of sporangiophores, followed by release of secondary zoospores within 12 h. Seedlings inoculated with zoospores began to die 2 weeks after emergence in a greenhouse. Symptoms on hypocotyls began as water-soaked lesions that turned black and thread-like. The causal agent was reisolated from infected seedlings, completing Koch's postulates. The disease was subsequently found in more than 15 separate fields, representing 5 of 11 sugar beet-growing counties in Nebraska and 1 county in Wyoming. In October, plants from the same fields were observed with stunted, distorted roots and superficial, scabby lesions associated with latent A. cochlioides infection. The pathogen could not be isolated from this stage but was confirmed by observing mature oospores within thin, stained sections under a microscope. The sections were additionally mixed with sterile potting soil and planted in the greenhouse with sugar beets. Several weeks after emergence, seedlings began to die, and the pathogen was reisolated. This represents the first report of Aphanomyces root rot and its spread in the Central High Plains. It also confirms that the described latent symptoms on sugar beet are caused by A. cochlioides. Reference: (1). W. F. Pfender et al. Plant Dis. 68:845, 1984.

scholarly journals Coccinonectria pachysandricola, Causal Agent of a New Foliar Blight Disease of Sarcococca hookeriana

Plant Disease ◽  
2019 ◽  
Vol 103 (6) ◽  
pp. 1337-1346 ◽  
Author(s):  
Catalina Salgado-Salazar ◽  
Nina Shiskoff ◽  
Nicholas LeBlanc ◽  
Adnan A. Ismaiel ◽  
Maxton Collins ◽  
...  
Keyword(s):  
Woody Plants ◽  
Causal Agent ◽  
Washington Dc ◽  
Disease Symptoms ◽  
Foliar Blight ◽  
Pathogenicity Tests ◽  
Artificial Inoculations ◽  
Blight Disease ◽  
Genome Assemblies ◽  
Severe Leaf

Woody plants of the Buxaceae, including species of Buxus, Pachysandra, and Sarcococca, are widely grown evergreen shrubs and groundcovers. Severe leaf spot symptoms were observed on S. hookeriana at the U.S. National Arboretum in Washington, DC, in 2016. Affected plants were growing adjacent to P. terminalis exhibiting Volutella blight symptoms. Fungi isolated from both hosts were identical based on morphology and multilocus phylogenetic analysis and were identified as Coccinonectria pachysandricola (Nectriaceae, Hypocreales), causal agent of Volutella blight of Pachysandra species. Pathogenicity tests established that Co. pachysandricola isolated from both hosts caused disease symptoms on P. terminalis and S. hookeriana, but not on B. sempervirens. Artificial inoculations with Pseudonectria foliicola, causal agent of Volutella blight of B. sempervirens, did not result in disease on P. terminalis or S. hookeriana. Wounding enhanced infection by Co. pachysandricola and Ps. foliicola on all hosts tested but was not required for disease development. Genome assemblies were generated for the Buxaceae pathogens that cause Volutella diseases: Co. pachysandricola, Ps. buxi, and Ps. foliicola; these ranged in size from 25.7 to 28.5 Mb. To our knowledge, this foliar blight of S. hookeriana represents a new disease for this host and is capable of causing considerable damage to infected plants.

scholarly journals First Report of Pink Seed of Common Bean Caused by Erwinia rhapontici

Plant Disease ◽  
2002 ◽  
Vol 86 (8) ◽  
pp. 921-921 ◽  
Author(s):  
H. C. Huang ◽  
R. S. Erickson ◽  
L. J. Yanke ◽  
H.-H. Mündel ◽  
T. F. Hsieh
Keyword(s):  
Common Bean ◽  
Gas Production ◽  
Water Soluble ◽  
Bacterial Suspension ◽  
Bean Plants ◽  
Southern Alberta ◽  
Pathogenicity Tests ◽  
Esculin Hydrolysis ◽  
Erwinia Rhapontici ◽  
Pink Pigment

In 2001, a new disease of common bean (Phaseolus vulgaris L.) caused by Erwinia rhapontici (Millard) Burkh. was detected in seed samples from southern Alberta, Canada. Infected seeds had pink or pinkish-brown lesions on the seed coat. The disease was found in great northern (cv. US1140), pink (cv. Viva), and pinto (cv. Othello) beans at low (<0.1%) frequencies. Isolation from surface-sterilized pink seeds resulted in bacterial cultures, which produced a water-soluble pink pigment on potato dextrose agar (PDA). Seven isolates were tested for physiological characteristics using conventional tests (1) and API 50CHE test strips (bioMérieux Canada, St. Laurent, Quebec), and tested for cellular fatty acids using the MIDI system (Newark, DE). All isolates were gram-negative, motile, facultative anaerobic rods with mucoid colonies and produced a pink pigment on PDA. They were positive for citrate utilization, catalase, methyl red, and Voges-Proskauer, and negative for arginine dihydrolase, lysine and ornithine decarboxylases, urease, gelatin liquification, indole production, oxidase, and gas production. Fatty acid profiles matched with E. rhapontici (approximately 30% each 16:0 and 16:1 ω7c/15:0 iso 2OH; 12% 18:1 ω7c: 8% each 17:0 cyclo and 14:0 3OH/16:1 iso; 4 to 5% each 12:0 and 14:0). Isolates were positive for acid production from: N-acetyl glucosamine, l-arabinose, amygdalin, arbutin, cellobiose, esculin (hydrolysis), d-fructose, d-fucose, d-galactose, β-gentiobiose, d-glucose, glycerol, i-myo-inositol, lactose, maltose, d-mannitol, d-mannose, melibiose, d-raffinose, l-rhamnose, ribose, salicin, d-sorbitol, sucrose, trehalose, and d-xylose. These results match published results for E. rhapontici (4). For pathogenicity tests, each isolate was inoculated in 30 pods from six bean plants (cv. US1140) as described for pink seed of peas (2). Each pod was inoculated with 0.1 ml of bacterial suspension, approximately 109 CFU/ml, by injection through the mid-rib at the basal end. The same number of uninoculated and water-inoculated pods served as controls. Plants were kept in the greenhouse (20 ± 5°C) for 4 weeks, after which isolations were done as described above. In duplicate experiments, all isolates caused lesions on pods extending up to 5 cm from the inoculation point with corresponding discoloration of seeds. The frequency of infected seeds varied among isolates, ranging from 20 to 50%. E. rhapontici was reisolated from seeds with lesions, but not asymptomatic seeds. The study concludes that pink seed of common bean is due to E. rhapontici, a pathogen previously reported on peas in Alberta, Canada (2), and Montana (3). References: (1) D. J. Brenner. Bergey's Manual of Systematic Bacteriology, vol.1, Williams and Wilkens, Baltimore, MD, 1984. (2) H. C. Huang et al. Can. J. Plant Pathol. 12:445, 1990. (3) B. K. Schroeder et al. Plant Dis. 86:188, 2002. (4) L. Verdonck et al. Int. J. Syst. Bacteriol. 37:4, 1987.

Molecular and Pathogenic Characteristics of Paecilomyces formosus, a New Causal Agent of Oak Tree Dieback in Iran

2019 ◽  
Vol 65 (6) ◽  
pp. 743-750 ◽  
Author(s):  
Mohammad Sabernasab ◽  
Samad Jamali ◽  
Alireza Marefat ◽  
Saeed Abbasi
Keyword(s):  
Causal Agent ◽  
Thermophilic Fungi ◽  
Oak Trees ◽  
Tree Dieback ◽  
Pathogenicity Tests ◽  
Oak Tree ◽  
Pathogen Recovery ◽  
Branch Dieback ◽  
Internal Transcribed Spacer Rdna

Abstract Oak dieback is one of the most important diseases that presently affects the Kermanshah oak forests (West Iran). During the period from 2013 to 2015, oak trees exhibiting branch dieback were sampled, and fungal colonies resembling those of the Paecilomyces sp. were obtained from diseased tissues. Based on morphology, physiology, and phylogeny of the internal transcribed spacer rDNA, all isolates were identified as Paecilomyces formosus. Pathogenicity tests in vivo were made on 2-year-old seedlings, potted Q. brantii plants, and excised branch sections under controlled conditions. Inoculated seedlings produced characteristic symptoms, and subsequent pathogen recovery confirmed pathogenicity. We determined these to be thermophilic fungi, which may be related to warming and drought. This is the first report of Paecilomyces formosus as the causal agent of Q. brantii dieback in Iran and the world.

scholarly journals Identification of the causal agent of “pata seca” in pepper crop production areas of Ecuador

2018 ◽  
Vol 44 (4) ◽  
pp. 338-343
Author(s):  
Miguel Angel Quilambaqui Jara ◽  
Antonio Carlos Maringoni
Keyword(s):  
Capsicum Annuum ◽  
Crop Production ◽  
Sclerotium Rolfsii ◽  
Causal Agent ◽  
Economic Losses ◽  
Fusarium Spp ◽  
Pathogenicity Tests ◽  
Production Areas ◽  
Disease Analysis ◽  
Santa Elena

ABSTRACT Cultivation of pepper (Capsicum annuum L.) has high economic relevance in Ecuador. Although the planted area is approximately 5704 ha, its productivity is low (3.17 t ha-1) relative to other countries in the region. In recent years, the spread and the development of a disease that leads the plant to death, known by farmers as “pata seca” and occurring in production zones located in Guayas and Santa Elena Provinces, have caused great economic losses. The aim of this study was to evaluate the effect of “pata seca” on commercial pepper crops during 2013 and 2014 and to identify the causal agent of such disease. Twenty-three farms were visited, where samples and data were collected. “Pata seca” was detected in 79.2% samples, and 53.6% plants had symptoms of this disease. Analysis of the samples collected in 2013 and 2014 indicated that the predominant fungi were Sclerotium rolfsii (31.17%, 49.64%) and Fusarium spp. (29.29%, 32.37%), respectively. Pathogenicity tests confirmed that S. rofsii is the major causal agent.

scholarly journals An Integrated Approach to Cultivar Evaluation and Selection for Imporving Suger Beet Profitability: A Successful Case Study for the Central High Plains

Plant Disease ◽  
2002 ◽  
Vol 86 (3) ◽  
pp. 192-204 ◽  
Author(s):  
R. M. Harveson ◽  
G. L. Hein ◽  
J. A. Smith ◽  
R. G. Wilson ◽  
C. D. Yonts
Keyword(s):  
Integrated Approach ◽  
High Plains ◽  
Successful Case ◽  
Selection For ◽  
Central High
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