​Bacterial Streak and Bulb Rot of Onion​

2021 ◽  
Keyword(s):  
Bulb Rot

scholarly journals Incidence and Etiology of Postharvest Fungal Diseases Associated with Bulb Rot in Garlic (Alllium sativum) in Spain

Foods ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1063
Author(s):  
Laura Gálvez ◽  
Daniel Palmero
Keyword(s):  
Negative Impact ◽  
Fusarium Species ◽  
Fungal Species ◽  
Postharvest Disease ◽  
Dry Rot ◽  
Fusarium Dry Rot ◽  
Causative Agents ◽  
Postharvest Handling ◽  
Pathogenicity Tests ◽  
Bulb Rot

In recent years, different postharvest alterations have been detected in garlic. In many cases, the symptoms are not well defined, or the etiology is unknown, which further complicates the selection of bulbs during postharvest handling. To characterize the different symptoms of bulb rot caused by fungi, garlic bulb samples were collected from six Spanish provinces in two consecutive years. Eight different fungal species were identified. The most prevalent postharvest disease was Fusarium dry rot (56.1%), which was associated with six Fusarium species. Fusarium proliferatum was detected in more than 85% of symptomatic cloves, followed by F. oxysporum and F. solani. Pathogenicity tests did not show a significant correlation between virulence and mycotoxin production (fumonisins, beauvericin, and moniliformin) or the mycelial growth rate. Penicillium allii was detected in 12.2% of the samples; it was greatly influenced by the harvest season and garlic cultivar, and three different morphotypes were identified. Stemphylium vesicarium and Embellisia allii were pathogenic to wounded cloves. Some of the isolated fungal species produce highly toxic mycotoxins, which may have a negative impact on human health. This work is the first to determine the quantitative importance, pathogenicity, and virulence of the causative agents of postharvest garlic rot in Spain.

scholarly journals First Report of a Garlic Bulb Rot Caused by Erwinia persicina in Europe

Plant Disease ◽  
2015 ◽  
Vol 99 (5) ◽  
pp. 723 ◽  
Author(s):  
L. Gálvez ◽  
J. Gil-Serna ◽  
M. García-Díaz ◽  
D. Palmero
Keyword(s):  
First Report ◽  
Garlic Bulb ◽  
Bulb Rot ◽  
Erwinia Persicina

Phylogeny and identification of Pantoea species associated with bulb rot and bacterial leaf blight of onion crops in Uruguay

Plant Disease ◽  
2021 ◽  
Author(s):  
Stefanie De Armas ◽  
Guillermo Alesio Galván ◽  
María Inés Lapaz ◽  
Pablo González-Barrios ◽  
Esteban Vicente ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Complex Disease ◽  
Bacterial Species ◽  
Housekeeping Genes ◽  
Leaf Blight ◽  
Rrna Gene ◽  
Breeding Lines ◽  
Gene Sequence Analysis ◽  
Bulb Rot ◽  
Physiological Tests

Onion is among the most consumed vegetables in Uruguay, grown in the Northwestern and Southern regions of the country. The onion supply presents interannual variations associated with significant postharvest losses, mainly caused by bacterial rots. Besides bulb rotting, onion leaf lesions as well as infections on seed-stalks during seed production may be devastating for some varieties under conducive conditions. This research aimed to identify the causal agents of bulb rots and leaf blight of onion crops in Uruguay. Symptomatic bulbs, seeds-stalks and leaves were collected from commercial fields from 2015 to 2020. Bacterial colonies were isolated and identified at genera level using physiological tests and 16S rRNA gene sequence analysis. A collection of 59 Pantoea spp. isolates was obtained (11 from bulbs and 48 from leaves and seeds-stalks). Multilocus sequence analysis (MLSA) using four housekeeping genes (rpoB, gyrB, leuS and fusA) allowed the assignment of the isolates to five Pantoea species: P. ananatis, P. agglomerans, P. allii, P. eucalypti and P. vagans. The last two species were not previously reported as onion pathogens elsewhere. The ability to cause disease symptoms was tested by leaf inoculation and red onion scale assays. Pantoea ananatis isolates showed the highest aggressiveness in both assays. Specific isolates from P. allii (MAI 6022), P. eucalypti (MAI 6036), P. vagans (MAI 6050), and Pantoea sp. (MAI 6049) ranked the second in aggressiveness on onion leaves, while only three isolates belonging to P. eucalypti (MAI 6036 and MAI 6058) and P. agglomerans (MAI 6045) exhibited the same scale clearing phenotype as P. ananatis. Leaf inoculation assays were also performed on a set of eight onion cultivars and breeding lines. Overall, P. ananatis MAI 6032 showed the highest aggressiveness in all tested cultivars, followed by P. eucalypti MAI 6036. The presence of new reported bacterial species leads to complex disease management and highlights the need for further studies on virulence factors and the epidemiology of these pathogens.

scholarly journals The Bacterium Pantoea ananatis Modifies Behavioral Responses to Sugar Solutions in Honeybees

Insects ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 692
Author(s):  
Ricarda Scheiner ◽  
Sina Strauß ◽  
Markus Thamm ◽  
Gerard Farré-Armengol ◽  
Robert R. Junker
Keyword(s):  
Behavioral Responses ◽  
Fruit Rot ◽  
Plant Fitness ◽  
Forest Trees ◽  
Agricultural Crops ◽  
Emerging Pathogen ◽  
Pantoea Ananatis ◽  
Low Concentrations ◽  
High Concentrations ◽  
Bulb Rot

1. Honeybees, which are among the most important pollinators globally, do not only collect pollen and nectar during foraging but may also disperse diverse microbes. Some of these can be deleterious to agricultural crops and forest trees, such as the bacterium Pantoea ananatis, an emerging pathogen in some systems. P. ananatis infections can lead to leaf blotches, die-back, bulb rot, and fruit rot. 2. We isolated P. ananatis bacteria from flowers with the aim of determining whether honeybees can sense these bacteria and if the bacteria affect behavioral responses of the bees to sugar solutions. 3. Honeybees decreased their responsiveness to different sugar solutions when these contained high concentrations of P. ananatis but were not deterred by solutions from which bacteria had been removed. This suggests that their reduced responsiveness was due to the taste of bacteria and not to the depletion of sugar in the solution or bacteria metabolites. Intriguingly, the bees appeared not to taste ecologically relevant low concentrations of bacteria. 4. Synthesis and applications. Our data suggest that honeybees may introduce P.ananatis bacteria into nectar in field-realistic densities during foraging trips and may thus affect nectar quality and plant fitness.

A Bulb Rot of Vidalia Sweet Onion Caused by Botrytis tulipae in Georgia

Plant Disease ◽  
1994 ◽  
Vol 78 ◽  
pp. 1218A ◽  
Author(s):  
D. R. Sumner
Keyword(s):  
Bulb Rot

scholarly journals Effects of Postharvest Onion Curing Parameters on the Development of Sour Skin and Slippery Skin in Storage

Plant Disease ◽  
2012 ◽  
Vol 96 (10) ◽  
pp. 1548-1555 ◽  
Author(s):  
B. K. Schroeder ◽  
J. L. Humann ◽  
L. J. du Toit
Keyword(s):  
Curing Temperature ◽  
Storage Duration ◽  
Inoculum Concentration ◽  
Burkholderia Gladioli ◽  
Duration Of Storage ◽  
Bacterial Rot ◽  
Bulb Rot ◽  
Sour Skin ◽  
And Storage ◽  
Limited Duration

The influence of postharvest curing temperature and duration on development of slippery skin (caused by Burkholderia gladioli pv. alliicola) and sour skin (caused by B. cepacia) in onion (Allium cepa) bulbs during storage was evaluated by inoculating bulbs of the storage cultivars ‘Redwing’ and ‘Vaquero’ with each of the pathogens after harvest, curing the bulbs at 25, 30, 35, or 40°C for 2 or 14 days, and storing the bulbs at 5°C for 1, 2, or 3 months. Noninoculated bulbs and bulbs injected with sterile water served as control treatments. The onion bulbs were from drip-irrigated, commercial onion crops grown in the semiarid Columbia Basin of central Washington in 2009 and 2010. Each bulb was cut through the point of inoculation from the neck to the basal plate to assess severity of bulb rot (percentage of cut bulb surface area with bacterial rot symptoms) after 1, 2, or 3 months of storage. Bulb rot severity in the 2009–10 and 2010–11 trials was negligible for noninoculated bulbs (mean of 4.0 and 4.5%, respectively) and bulbs injected with water (6.2 and 10.1%, respectively) compared with bulbs inoculated with B. cepacia (34.6 and 39.8%, respectively) and B. gladioli pv. alliicola (20.7 and 27.4%, respectively). Bulbs inoculated with B. cepacia developed significantly more severe rot than those inoculated with B. gladioli pv. alliicola, even though a 10-fold greater inoculum concentration was used for B. gladioli pv. alliicola, demonstrating the more aggressive nature of B. cepacia compared with B. gladioli pv. alliicola. Severity of bulb decay caused by B. cepacia or B. gladioli pv. alliicola was affected significantly (P < 0.05) by season (trial), cultivar, curing temperature, curing duration, and storage duration, with significant interactions among these factors. In both trials and for both pathogens, bulb rot was significantly more severe the greater the curing temperature and the severity of bulb rot was significantly greater when bulbs were cured for 14 versus 2 days prior to cold storage. Overall, the severity of bulb rot was greater with a longer duration of storage after curing. This increase in bulb rot severity, which resulted from an increase in curing temperature and duration, was significantly greater for Vaquero than Redwing and significantly greater for bulbs inoculated with B. cepacia than B. gladioli pv. alliicola. The results suggest that postharvest curing at temperatures <35°C for a limited duration can significantly reduce the severity of sour skin or slippery skin in storage.

scholarly journals Gene Genealogies and AFLP Analyses in the Fusarium oxysporum Complex Identify Monophyletic and Nonmonophyletic Formae Speciales Causing Wilt and Rot Disease

2000 ◽  
Vol 90 (8) ◽  
pp. 891-900 ◽  
Author(s):  
Robert P. Baayen ◽  
Kerry O'Donnell ◽  
Peter J. M. Bonants ◽  
Elizabeth Cigelnik ◽  
Laurens P. N. M. Kroon ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Dna Sequences ◽  
Mitochondrial Gene ◽  
Elongation Factor ◽  
Small Subunit ◽  
Vegetative Compatibility Groups ◽  
Formae Speciales ◽  
Evolutionary Origins ◽  
Bulb Rot ◽  
Rot Disease

The monophyletic origin of host-specific taxa in the plant-pathogenic Fusarium oxysporum complex was tested by constructing nuclear and mitochondrial gene genealogies and amplified fragment length polymorphism (AFLP)-based phylogenies for 89 strains representing the known genetic and pathogenic diversity in 8 formae speciales associated with wilt diseases and root and bulb rot. We included strains from clonal lineages of F. oxysporum f. spp. asparagi, dianthi, gladioli, lilii, lini, opuntiarum, spinaciae, and tulipae. Putatively nonpathogenic strains from carnation and lily were included and a reference strain from each of the three main clades identified previously in the F. oxysporum complex; sequences from related species were used as outgroups. DNA sequences from the nuclear translation elongation factor 1α and the mitochondrial small subunit (mtSSU) ribosomal RNA genes were combined for phylogenetic analysis. Strains in vegetative compatibility groups (VCGs) shared identical sequences and AFLP profiles, supporting the monophyly of the two single-VCG formae speciales, lilii and tulipae. Identical genotypes were also found for the three VCGs in F. oxysporum f. sp. spinaciae. In contrast, multiple evolutionary origins were apparent for F. oxysporum f. spp. asparagi, dianthi, gladioli, lini, and opuntiarum, although different VCGs within each of these formae speciales often clustered close together or shared identical EF-1α and mtSSU rDNA haplotypes. Kishino-Hasegawa analyses of constraints forcing the monophyly of these formae speciales supported the exclusive origin of F. oxysporum f. sp. opuntiarum but not the monophyly of F. oxysporum f. spp. asparagi, dianthi, gladioli, and lini. Most of the putatively nonpathogenic strains from carnation and lily, representing unique VCGs, were unrelated to F. oxysporum f. spp. dianthi and lilii, respectively. Putatively nonpathogenic or rot-inducing strains did not form exclusive groups within the molecular phylogeny. Parsimony analyses of AFLP fingerprint data supported the gene genealogy-based phylogram; however, AFLP-based phylogenies were considerably more homoplasious than the gene genealogies. The predictive value of the forma specialis naming system within the F. oxysporum complex is questioned.

scholarly journals Microbial Communities Associated with Storage Onion

2018 ◽  
Vol 2 (1) ◽  
pp. 35-41 ◽  
Author(s):  
Svetlana N. Yurgel ◽  
Lord Abbey ◽  
Nancy Loomer ◽  
Rosalie Gillis-Madden ◽  
Melissa Mammoliti
Keyword(s):  
Microbial Communities ◽  
Allium Cepa ◽  
Abiotic Factors ◽  
Fungal Communities ◽  
Pathogenic Microorganisms ◽  
Community Based ◽  
Disease Symptoms ◽  
Onion Bulbs ◽  
Bulb Rot ◽  
Apparently Healthy

Onion (Allium cepa) bulb rot is an important pathological problem worldwide, as it is caused by diverse pathogens, bacterial and fungal. The diversity and structure of microbial communities associated with apparently healthy and diseased onion bulbs were analyzed. The community-based approach allowed identification of a number of potential pathogenic microorganisms associated with onion bulbs affected by disease under storage environments. Enterobacteriaceae, Burkholderia, Gluconobacter, Acinetobacter, Pseudomonas, Citrobacter, Nectriaceae, Botrytis, Wickerhamomyces, Penicillium, and Candida were the most relatively abundant bacterial and fungal taxa in the diseased onion bulb dataset. It was found that these taxa are also widely distributed in the bulbs without apparent disease symptoms. Additionally, several potential fermenters were detected in onion tissue. These data suggest that, in addition to abiotic factors, fermentation plays a role in the storage spoilage of onion bulbs. It was also shown that bacterial and fungal communities differ in their diversity and structure between individual onions affected by bulb rot. The identification of dinoflagellates Symbiodinium in onion bulbs suggested that this eukaryote might have a much broader spectrum of habitats and eukaryotic hosts.

FURTHER EXPERIMENTS ON THE FUSARIUM BULB ROT OF NARCISSUS

1935 ◽  
Vol 22 (4) ◽  
pp. 684-708 ◽  
Author(s):  
LILIAN E. HAWKER
Keyword(s):  
Bulb Rot
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