Temperature and Effects of Seed-borne Botrytis cinerea or Alternaria linicola on Emergence of Linseed (Linum usitatissimum) Seedlings

Experiments were done at temperatures from 5 to 20 C to investigate the effects of infection of linseed seed (cv. Antares) by Botrytis cinerea or Alternaria linicola on seedling emergence and to study transmission of the pathogens from seed to seedlings. In one experiment with freshly harvested seed, the maximum percentage emergence decreased linearly as the incidence of B. cinerea in seed increased from 0 to 83% at 18 C day/12 C night temperatures. In another experiment, the decrease in percentage emergence of seed associated with infection by B. cinerea. the transmission of the pathogen to seedlings to produce disease symptoms on their hypocotyls and the incidence of post-emergence death all increased as temperature decreased from 20 to 5 C. However, the decrease in percentage emergence of seed associated with infection by A. linicola and the transmission of the pathogen to seedlings to produce cotyledon lesions both increased as temperature increased from 5 to 20 C. There was little effect of either pathogen on the time from sowing to 36% of maximum emergence, which decreased with increasing temperature. In a subsequent experiment at 10 C comparing seed infected with B.cinerea or A. linicola. using the same seed sources as in the previous experiments, infection by A. linicola decreased emergence more than infection by B. cinerea , even though the incidence of A. linicola in the seed was smaller. Analyses of position and parallelism suggested that regressions of maximum percentage emergence (logitransformed) against temperature were fitted best by non-parallel lines for seed infected by B. cinerea or A. linicola.     

A study of the longevity of the seed-borne parasites of flax in relation to the storage of the seed

From 1939 to 1947 observations were made on the longevity of Colletotrichumlinicola Pethybr. & Laff., Polyspora Lini Laff., Botrytis cinerea F t ., and Phoma sp. occurring to different extents as seed-borne parasites of naturally contaminated samples of flax seed held under ordinary conditions of storage. The results obtained, together with the germination capacity of the seed estimated on different occasions during storage, are given and show that the longevity of the fungi considered varies within the following limits: Colletotrichum linicola , 26–69 months, Polyspora Lini , 16–55 months, Botrytis cinerea , 16–40 months and Phoma sp. 27–43 months. The data provide grounds for suggesting that the higher the percentage number of seeds contaminated with Polyspora Lini the longer will be the time taken for the death of the parasite to occur. As the time taken for the deactivation of the parasites is normally much longer than that for which flax seed for sowing purposes can be safely stored, prolonged storage of the seed does not commend itself as a likely method for securing the control of the diseases caused by seed-borne fungi. The germination capacity of the seed was normally found to be seriously impaired by the time all the parasites had died.     

Survival and seed to seedling transmission of Alternaria linicola on linseed

Alternaria linicola survived as thick-walled chlamydospores in hyphal or conidial cells on infected linseed stem debris, either on the soil surface or buried in the soil, during the period between the harvest of linseed and sowing of the following crop (September - April). Conidia produced on these debris under favourable conditions were not only viable but also pathogenic to young linseed seedlings. Infected stem debris increased the incidence of infected seedlings which emerged from infected seed (incidence of A. linicola 1% to 28%), especially if the debris was on the soil surface rather than buried. A. linicola also survived between successive linseed crops on infected volunteer linseed plants which survived the low temperatures in winter and on the weed Veronica persica. A. linicola was more effectively transmitted from infected seeds to seedlings at temperatures 15–25°C than at 10°C. The incidence of the disease on seedlings which emerged from infected seed was positively correlated with the amount of seed-borne inoculum, whereas the proportion of seedlings which emerged was negatively correlated with the incidence of A. linicola on the seed.     

The relation between the contamination of flax seed with Polyspora Lini Laff. and Colletotrichum linicola Pethybr. & Laff. and the incidence of disease in the crop

Using naturally contaminated seed it is shown that the incidence of the seedling, stem-break and browning phases of attack by Polyspora Lini Laff. in flax crops is related to the contamination of the seed with the parasite, the relationship being closer at low or moderate than at high levels of seed contamination. Heavy attacks of the disease did not occur when the number of contaminated seeds was less than 5%. A similar relationship was found to exist between the contamination of seed with Colletotrichum linicola Pethybr. & Laff. and the incidence of seedling blight in the crops.     

Survival and inoculum potential of conidia and chlamydospores of Fusarium oxysporum f.sp. lini in soil

The kinetics of survival and inoculum potential of Fusarium oxysporum f.sp. lini were studied in soil. Two types of inoculum were compared: microconidia freshly harvested from a laboratory-grown culture and microchlamydospores produced in sterilized soil. Introduced at the same inoculum densities into a natural soil, the two types of inoculum showed similar behavior; the inoculum densities changed little with time, at least during 100 days. However, the two types of inoculum did differ in disease potential. A higher percentage of microchlamydospores than microconidia germinated in the rhizosphere of flax seedlings, and the heterotrophic fluorescein diacetate hydrolysing activity of the microchlamydospores was 100 times higher than that of microconidia. Moreover, the microchlamydospores produced more disease on flax than the microconidia even at a much lower inoculum density.     

A bacteriological investigation of the effectiveness of cleaning and disinfection procedures for toilet hygiene

The bacterial contamination of hospital and institutional toilets and toilet areas which were cleaned daily was investigated. The effect of daily disinfection with hypochlorite or a quaternary ammonium product, or with a continuous-release hypochlorite disinfectant system, based on the chlorine-releasing agent trichloroisocyanuric acid, was determined. The continuous release system produced substantial and sustained reduction in contamination of the toilet itself (water, toilet bowl and rim) and some reduction in contamination of sites surrounding the toilet (seat, floor, and air). By contrast, although daily disinfection produced some reduction in contamination compared with daily cleaning, the reductions were less than that associated with the continuous release system and indicated the inadequacy of daily disinfection and/or cleaning for toilets where effective procedures are required.     

A bacteriological investigation of the effectiveness of cleaning and disinfection procedures for toilet hygiene

S cott , E. & B loomfield , S.F. 1985. A bacteriological investigation of the effectiveness of cleaning and disinfection procedures for toilet hygiene, Journal of Applied Bacteriology 59 , 291–297.
The bacterial contamination of hospital and institutional toilets and toilet areas which were cleaned daily was investigated. The effect of daily disinfection with hypochlorite or a quaternary ammonium product, or with a continuous-release hypochlorite disinfectant system, based on the chlorine-releasing agent trichloro-isocyanuric acid, was determined. The continuous release system produced substantial and sustained reduction in contamination of the toilet itself (water, toilet bowl and rim) and some reduction in contamination of sites surrounding the toilet (seat, floor, and air). By contrast, although daily disinfection produced some reduction in contamination compared with daily cleaning, the reductions were less than that associated with the continuous release system and indicated the inadequacy of daily disinfection and/or cleaning for toilets where effective procedures are required.     

Flax in Neolithic and Bronze Age Greece: archaeobotanical evidence

This paper presents an overview of archaeobotanical finds of Linum usitatissimum from Neolithic and Bronze Age Greece, bringing together published records of this plant as well as some recently retrieved, unpublished finds. In addition, charred flax seed concentrations from five prehistoric sites from the region of Macedonia in northern Greece, are examined in detail. The Neolithic sites are Makriyalos, Mandalo, Arkadikos, Dikili Tash, dated to the Late and Final Neolithic and Archondiko, dated to the end of the Early Bronze Age. Archaeobotanical composition and contextual information are used in order to explore the cultivation and potential uses of flax at each site. By the 5th millennium b.c. a flax weed flora had probably developed in the region. The use of flax seed for oil extraction and flax stems for flax fibre preparation can only be speculated upon and these uses are discussed within the context of other archaeological finds related to plant oil production and weaving. It is also possible that flax may have been used for medicinal purposes. Despite a striking paucity in archaeobotanical remains from southern Greece, textual evidence available from the Mycenean palace archives in Linear B clearly documents the cultivation of flax and flax fibre production.     

Effects of seed coatings with thiamethoxam on germination and flea beetle control in flax

Flea beetles damage the seedlings before and after emergence and later the top of the plants as well, resulting in forking of the stem. This is unacceptable for the flax fibre industry, since it influences fibre quality negatively. Five field trials were carried out in 2001, 2003 and 2004 to assess the control of the flax flea beetles Longitarsus parvulus (Payk) and the large flax flea beetle Aphthona euphorbiae (Schrank) by film coating the seeds with thiamethoxam in fibre flax crops (Linum usitatissimum L.). Seed treatments were compared with untreated seeds and standard post emergence sprays with deltamethrin or parathion-methyl. Film coatings of the seeds with thiamethoxam formulated as 280 g/l, 350 g/l and 600 g/l were used. Thiamethoxam 350 g/l at rates of 9.1 and 18.2 g a.i./kg seed resulted in phytotoxicity, shown by a decrease of emergence. Application of thiamethoxam 350 g/l and 600 g/l at rates of 1.1 g a.i./kg seed and higher resulted in excellent flea beetle control. Application of thiamethoxam 280 g/l at a rate of 1.1 g a.i./kg seed showed no decrease of attack in comparison with the standard spray treatment. Seed treatment with thiamethoxam 600 g/l at 0.6 g a.i./kg showed insufficient protection.     

EFFECTS OF NUTRIENT TREATMENTS ON STEM-BREAK OF FLAX (CAUSED BY POLYSPORA LINI LAFF.)

Flax was grown in prepared composts containing different levels and ratios of nitrogen, phosphorus and potassium. When the cotyledons were inoculated with Polyspora lini Laff. the incidence of the seedling phase of the disease was not influenced by nutrient treatments, all plants being attacked. In such inoculated plants the lowest incidence of the stem-break phase of the disease occurred in composts deficient in phosphorus. Increasing doses of the phosphatic fertilizer were associated with increases in susceptibility to stem-break as well as in plant height and fibre yield. Small additions of the fertilizer produced little effect. In one experiment the incidence of stem-break was directly and very significantly correlated with the percentage of phosphorus in the plants when nitrogen and potassium were held constant. Significant correlations were not found to exist between the incidence of stem-break and the percentage of nitrogen or potassium in plants when the other two appropritate variables were held constant.     

Analysis of the sociodemography of gonorrhoea in Leeds, 1989-93.

OBJECTIVE: To investigate the epidemiology of gonorrhoea in an urban area in the United Kingdom. DESIGN: Analysis of all cases of gonorrhoea with regard to age, sex, ethnic group, and socioeconomic group with 1991 census data as a denominator. SETTING: Leeds, a comparatively large urban area (population around 700,000) in the United Kingdom. SUBJECTS: All residents of Leeds with culture proved cases of gonorrhoea during 1989-95. MAIN OUTCOME MEASURE: Relative risk of gonorrhoea. RESULTS: Sex, age, race, and socioeconomic group and area of residence were all independently predictive of risk of infection. Young black men aged 20-29 were at highest risk, with incidences of 3-4% per year. Black subjects were 10 times more likely than white subjects to acquire infection, and subjects from the most deprived socioeconomic areas were more than four times more likely than those from the most affluent areas to acquire infection. CONCLUSIONS: Different ethnic and socioeconomic groups vary in their risk of infection with gonorrhoea within an urban area. Targeted interventions and screening to reduce the incidence of sexually transmitted disease are now priorities.     

Flax in Sweden: the archaeobotanical, archaeological and historical evidence

The earliest recorded evidence of flax being cultivated in Sweden is from the end of the Bronze Age/beginning of the Iron Age. Later, from ca. a.d. 1100 and onwards, flax became an economically important plant in the country, and during the 12th to 16th centuries there was a substantial increase in the Swedish export of linen to other parts of Europe. Alongside its extensive cultivation, a set of cultural traditions and rituals was eventually built up around flax. The objective of this article is to draw an outline of the history of flax cultivation in Sweden and to present the relevant prehistoric and historic source material. A point of discussion will be the different roles that fibre flax and oil flax played over a long period of time and the problem of seed corn import for the development of domestic fibre flax in the country. The study is based on the prehistoric archaeobotanical record, mainly charred seeds from the Swedish Iron Age (ca. 500 b.c.–a.d. 1050), the archaeological record, documentary evidence and folklore.     

Einfluß der Behandlung von Rübensaatgut mit Rhizosphärebakterien auf den Befall durch Pilze der Gattung Pythium I. Antagonistische Wirkung verschiedener Bakterienisolate gegenüber Pythium spp.

Abstract The influence of a seed-dressing with rhizosphere bacteria on the infection of sugarbeet by fungi of the genus Pythium I. Antagonistic effect of different bacterial isolates towards Pythium spp.
Seed treatment with selectively isolated rhizosphere bacteria from the fluorescent pseudomonad group can protect sugar beet seedlings from damping-off caused by species of Pythium. The antagonistic rhizobacteria were equally effective in different soil substrates, both unsterilized and steam-sterilized. Antagonistic activity of an isolate was similar within seeds of a sugarbeet cultivar but different when different cultivars were compared. The number of bacteria adhering to the seed of eachcultivar which influenced the level of antagonism to Pythium infection, varied with seed morphology. A mixture of the three different isolates did not increase antagonistic activity when compared to the activity of the isolates individually.     

Varietal Resistance of Flax to Disease

Field experiments, using contaminated seed, have been carried out from 1941 to 1947 to study the reaction of a wide range of both fibre and oil varieties of Linum usitatissimum to attack by Polyspora Lini Laff., Colletotrichum linicola Pethybr. & Laff., Phoma sp. and Melampsora Lini (Ehrenb.) LéV. The tests made with Colletotrichum linicola were supplemented by direct inoculation experiments with young seedlings grown under greenhouse or laboratory conditions.
None of the varieties tested proved to be immune to attack by Polyspora Lini, Colletotrichum linicola or Phoma sp. Herkules, Concurrent, Hindi, La Plata, Saginaw x Ottawa 770 B and Winona x Ottawa 770 B were resistant to the stem-break and browning phases of attack by Polyspora Lini ; Bison, Hindi and La Plata were resistant to attacks by Colletotrichum linicola , while Hindi and La Plata showed some resistance to Phoma sp. Immunity or a 'high' measure of resistance to attack by Melampsora Lini was exhibited by Formosa, Stakhanovets, Textilshchik, U.S.S.R. No. 2 (ex Dugejheshchya), Wada, Argentine Selection (C.I. 112), Baladi, Bolley Golden (C.I. 644), Bombay (C.I. 42), Hindi, Italia Roma (C.I. 1005–2), J.W.S. (C.I. 708–1), Koto (C.I. 872), Kenya (C.I. 709–1), La Plata, Newland (C.I. 188), Ottawa 770B (C.I. 355), Pale Blue Crimped (C.I. 647), Tammes Pale Blue (C.I. 333–1), Williston Golden (C.I. 25–1) and C.I. 836.
All varieties did not show the same reactions to stem-break as to the browning phase of attack by Polyspora Lini and similar differences were noted in the case of the uredospore and teleutospore stages of Melampsora Lini. In certain varieties the stems showed a greater resistance to attack by Polyspora Lini or Melampsora Lini than the leaves.
Seeds of all varieties tested in the field experiments became heavily attacked with Polyspora Lini (except in La Plata), Colletotrichum linicola and Phoma sp.     

Autoactive alleles of the flax L6 rust resistance gene induce non-race-specific rust resistance associated with the hypersensitive response

L6 is a nucleotide binding site-leucine rich repeat (NBS-LRR) gene that confers race-specific resistance in flax (Linum usitatissimum) to strains of flax rust (Melampsora lini) that carry avirulence alleles of the AvrL567 gene but not to rust strains that carry only the virulence allele. Several mutant and recombinant forms of L6 were made that altered either the methionine-histidine-aspartate (MHD) motif conserved in the NBS domain of resistance proteins or exchanged the short domain C-terminal to the LRR region that is highly variable among L allele products. In transgenic flax some of these alleles are autoactive; they cause a gene dosage-dependent dwarf phenotype and constitutive expression of genes that are markers for the plant defense response. Their effects and penetrance ranged from extreme to mild in their degree of plant stunting, survival, and reproduction. Dwarf plants were also resistant to flax rust strains virulent to wild-type L6 plants, and this nonspecific resistance was associated with a hypersensitive response (HR) at the site of rust infection. The strongest autoactive allele, expressed in Arabidopsis from an ethanol-inducible promoter, gave rise to plant death dependent on the enhanced disease susceptibility 1 (EDS1) gene, which indicates that the mutant flax (Linaceae) L6 gene can signal cell death through a defined disease-resistance pathway in a different plant family (Brassicaceae).     

Subpopulation characteristics of egg-contaminating Salmonella enterica serovar Enteritidis as defined by the lipopolysaccharide O chain

Characterization of Salmonella enterica serovar Enteritidis was refined by incorporating new data from isolates obtained from avian sources, from the spleens of naturally infected mice, and from the United Kingdom into an existing lipopolysaccharide (LPS) O-chain compositional database. From least to greatest, the probability of avian isolates producing high-molecular-mass LPS O chain ranked as follows: pooled kidney, liver, and spleen; intestine; cecum; ovary and oviduct; albumen; yolk; and whole egg. Mouse isolates were most like avian intestinal samples, whereas United Kingdom isolates were most like those from the avian reproductive tract and egg. Non-reproductive tract organ isolates had significant loss of O chain. Isogenic isolates that varied in ability to make biofilm and to be orally invasive produced different O-chain structures at 25 degrees C but not at 37 degrees C. Hens infected at a 91:9 biofilm-positive/-negative colony phenotype ratio yielded only the negative phenotype from eggs. These results indicate that the environment within the hen applies stringent selection pressure on subpopulations of S. enterica serovar Enteritidis at certain points in the infection pathway that ends in egg contamination. The avian cecum, rather than the intestines, is the early interface between the environment and the host that supports emergence of subpopulation diversity. These results suggest that diet and other factors that alter cecal physiology should be investigated as a means to reduce egg contamination.     

Agricultural recovery of a formerly radioactive area: II. Systematic proteomic characterization of flax seed development in the remediated Chernobyl area

Molecular characterization of crop plants grown in remediated, formerly radioactive, areas could establish a framework for future agricultural use of these areas. Recently, we have established a quantitative reference map for mature flax seed proteins (Linum usitatissimum L.) harvested from a remediated plot in Chernobyl town. Herein we describe results from our ongoing studies of this subject, and provide a proteomics-based characterization of developing flax seeds harvested from same field. A quantitative approach, based on 2-dimensional electrophoresis (2-DE) and tandem mass spectrometry, yielded expression profiles for 379 2-DE spots through seed development. Despite the paucity of genomic resources for flax, the identity for 102 proteins was reliably determined. These proteins were sorted into 11 metabolic functional classes. Proteins of unknown function comprise the largest group, and displayed a pattern of decreased abundance throughout seed development. Analysis of the composite expression profiles for metabolic protein classes revealed specific expression patterns during seed development. For example, there was an overall decrease in abundance of the glycolytic enzymes during seed development.     

Field and laboratory studies of the susceptibility of the green treefrog (Hyla cinerea) to Batrachochytrium dendrobatidis infection

Amphibians worldwide are experiencing devastating declines, some of which are due to the amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd). Populations in the southeastern United States, however, have not been noticeably affected by the pathogen. The green treefrog (Hyla cinerea) is abundant and widespread in the southeastern United States, but has not been documented to harbor Bd infection. This study examined the susceptibility of H. cinerea to two strains of Bd in the lab and the prevalence of infection in wild populations of this species in southeastern Louisiana. Although we were able to infect H. cinerea with Bd in the lab, we did not observe any clinical signs of chytridiomycosis. Furthermore, infection by Bd does not appear to negatively affect body condition or growth rate of post-metamorphic individuals. We found no evidence of infection in surveys of wild H. cinerea. Our results suggest that H. cinerea is not susceptible to chytridiomycosis post-metamorphosis and probably is not an important carrier of the fungal pathogen Bd in the southeastern United States, although susceptibility at the larval stage remains unknown.     

Hospital Sanitation: the Massive Bacterial Contamination of the Wet Mop

Following the demonstration of massive spread of bacterial contamination throughout the hospital by the wet-mopping techniques in use, quantitative studies were undertaken to determine the source of contamination and to institute measures of control. It was found that mops, stored wet, supported bacterial growth to very high levels and could not be adequately decontaminated by chemical disinfection. Laundering and adequate drying provided effective decontamination, but build-up of bacterial counts occurred if mops were not changed daily or if disinfectant was omitted from the wash-water. Recommendations were based upon the experimental findings.