Search results for "Blight"
showing 10 items of 30 documents
Exploring new roles for the rpoS gene in the survival and virulence of the fire blight pathogen Erwinia amylovora
2014
Erwinia amylovora causes fire blight in economically important plants of the family Rosaceae. This bacterial pathogen spends part of its life cycle coping with starvation and other fluctuating environmental conditions. In many Gram-negative bacteria, starvation and other stress responses are regulated by the sigma factor RpoS. We obtained an E. amylovora rpoS mutant to explore the role of this gene in starvation responses and its potential implication in other processes not yet studied in this pathogen. Results showed that E. amylovora needs rpoS to develop normal starvation survival and viable but nonculturable (VBNC) responses. Furthermore, this gene contributed to stationary phase cross-…
Impact of Green Manure and Vermicompost on Soil Suppressiveness, Soil Microbial Populations, and Plant Growth in Conditions of Organic Agriculture of…
2015
The impact of organic amendments on the soil microorganisms and plant growth and health in conditions of organic agriculture of Northern temperate climate was analyzed. Some case studies dealing with green manure or vermicompost amendments are discussed giving deeper analyses of the vermicompost impact on plant growth. The first case study is about the impact of green manure on soil microbial populations and soil suppressiveness against such pathogens as late blight, potato scab, and black scurf of potato in organic agriculture. The second case study is about the use of vermicompost in organic starch potato cultivation. Significantly higher numbers of all groups of analyzed cultivable micro…
Blight Caused by Sclerotium rolfsii on Potted Ornamental Citrus in Sicily.
2019
Approximately 140,000 container-grown ornamental citrus plants are produced each year in the province of Catania (eastern Sicily). In the spring of 2006, a severe blight was observed in a commercial nursery in Catania on 2-month-old rooted cuttings of lemon (Citrus limon (L.) Burm.) and calamondin (× Citrofortunella mitis (Blanco) J. W. Ingram & H. E. Moore). Approximately 80% of the nursery stock of 2,000 cuttings was affected. Cuttings were grown in 7.5-cm2 pots made with compressed peat and wood pulp at 28 to 30°C with 95 to 100% relative humidity on benches in a greenhouse, The pot mix was composed of peat, perlite, and soil (2:1:2). Cuttings showed a dark brown necrotic lesion at …
Cellular, physiological, and molecular adaptive responses of Erwinia amylovora to starvation.
2013
Erwinia amylovora causes fire blight, a destructive disease of rosaceous plants distributed worldwide. This bacterium is a nonobligate pathogen able to survive outside the host under starvation conditions, allowing its spread by various means such as rainwater. We studied E. amylovora responses to starvation using water microcosms to mimic natural oligotrophy. Initially, survivability under optimal (28 °C) and suboptimal (20 °C) growth temperatures was compared. Starvation induced a loss of culturability much more pronounced at 28 °C than at 20 °C. Natural water microcosms at 20 °C were then used to characterize cellular, physiological, and molecular starvation responses of E. amylovora. Ch…
Ecological role of mycotoxins produced by Fusarium graminearum : consequences of the presence of deoxynivalenol (DON) in crop residues on the soil mi…
2012
Fusarium graminearum is a plant pathogenic fungus, causing devastating disease “Fusarium head blight” (FHB) in cereals including wheat and maize. It also contaminates the grains with mycotoxins including deoxynivalenol (DON) which are toxic to human and animals. This disease has resulted in the serious losses in grain yield and quality. We established through a first bibliographic review that during off season fungus survives saprophytically on the crop residues (ecological habitat) and serves as primary inoculum for the next season crop. However, we noticed also that the literature was poor about the role mycotoxins could play in the establishment of F. graminearum in such a habitat. The m…
First Report of Leaf Spot and Blight Caused by Ralstonia pickettii on Bird of Paradise Tree in Italy
2008
Bird of Paradise tree (Strelitzia alba (L. f.) Skeels) is an ornamental perennial tropical plant grown in southern Italy. In the summer of 2006 and 2007, a widespread, severe leaf disease was observed on seedlings and 1- to 2-year-old plants in two glasshouses located in eastern Sicily. Disease incidence ranged from 10 to 25%. Symptoms on the leaves consisted of dark brown-to-black stripes of varying length and found between the lateral veins. Lesions sometimes coalesced into a large area of necrotic tissue. Symptomatic tissues were ground in a drop of sterile distilled water (SDW) with a scalpel. Suspensions were streaked on King's medium B (KB), nutrient agar, and yeast extract nutrient …
First Report of Botrytis Blight on Medinilla magnifica and Various Species of Mandevilla and Allamanda in Italy.
2019
Medinilla magnifica Lindl., Mandevilla splendens (Hook.) Woodson, the hybrid Mandevilla × amoena ‘Alice du Pont’ (pink allamanda), and various species of Allamanda, such as A. cathartica L. and A. blanchetii A. DC. (purple allamanda), are grown in Sicily as ornamentals. After a frost in early December 2001, a sudden wilt of container-grown cuttings of these tropical species was observed in a plastic-covered production greenhouse, with ≈30% of M. magnifica plants and 70% of Mandevilla and Allamanda plants affected. Medinilla plants (≈35 cm high) had been rooted in trays and transplanted individually in 30-cm-diameter pots. Allamanda (recently rooted cuttings) and Mandevilla (well-establishe…
Investigation of the resistance of different varieties of buckwheat to infectious diseases after the pre-sowing treatment of seeds and vegetating pla…
2016
In the work it was investigated the influence of sodium humate, biological products "Vermisol", "Vitasym" and "Bioeco-funge-1" on buckwheat lesion of Botrytis bunch rot, Downy mildew, Ascochyta blight, bacteriosis, burn virus and a complex of diseases after pre-sowing treatment of seeds and vegetating plants of Victoria, Roxolana, Kara-Dag, Rubra, Zelenokvitkova-90,Stepova, Elena, Aelita, Lada and Fagopyrum tataricum Gaertn buckwheat varieties. The prospects of these biological products use under agrocenosis conditions to protect the crops of buckwheat from the complex of diseases were shown. The highest effi- ciency identified for the drug "Bioecofunge-1" which , in addition to protecting …
Exopolysaccharides favor the survival of Erwinia amylovora under copper stress through different strategies.
2010
Erwinia amylovora causes fire blight, a destructive disease of rosaceous plants very difficult to control. We demonstrated that copper, employed to control plant diseases, induces the "viable-but-nonculturable" (VBNC) state in E. amylovora. Moreover, it was previously reported that copper increases production of its main exopolysaccharide (EPS), amylovoran. In this work, the copper-complexing ability of amylovoran and levan, other major EPS of E. amylovora, was demonstrated. Following this, EPS-deficient mutants were used to determine the role of these EPSs in survival of this bacterium in AB mineral medium with copper, compared to their wild type strain and AB without copper. Tot…
Soybean Diseases Caused by Genus Pseudomonas Phytopathenes Bacteria
2019
The rationale and experimental confirmation of the role of the bacteria of the Pseudomonas genus in the pathogenesis of soybean, and the investigation of the biological properties of the main causative agent Pseudomonas savastanoi pv. glycines. Methods. Theoretical generalization, laboratory-model research, phytopathological, microbiological, physiological, biochemical and genetic methods. Results. The largest group of pathogens in different soil-climatic zones of Ukraine consists of bacteria of the genus Pseudomonas was established. Their biological properties have been investigated and the methods for identification of the dominant type of phytopathogenic bacteria causing bacterial blight…