Silicon,biological seed treatment and cutting reduce the intensity of leaf spot diseases affecting Lolium multiflorum

Italian ryegrass is a major pasture crop cultivated mainly for feeding cattle in southern Brazil. The choice of crop is based on nutritional quality and the shortage of pastures that occur during the winter in the southernmost part of Brazil. In this region, the production of biomass and seeds are threatened by diseases, in particular fungal diseases that affect the foliage. In this study we identified and monitored the natural occurrence of a complex of leaf spotting diseases and evaluated the effects of combined management practices to reduce the intensity of foliar diseases: seed treatment with Trichoderma atroviride, soil amendment with silicon and cutting frequency (none, one or two cuts). Three diseases were present in a two-season experiment: grey leaf spot (Pyricularia oryzae), brown leaf spot (Bipolaris sorokiniana) and parrot's eye leaf spot (Cercospora sp.). Grey leaf spot had the highest severity, regardless of treatment, during the first season, and was the only disease present in the following season. Grey leaf spot dominated, and plants receiving only one cut were more prone to P. oryzae infection. The treatments with silicon or T. atroviride reduced the relative disease by 40% to 80%, in relation to untreated and uncut regimes. This study showed the main leaf spot diseases associated with L. multiflorum. Moreover, it demonstrates for the first time in the region the effectiveness of reducing leaf spot via the application of silicon in the soil, inoculation of seeds with T. atroviride and managing the cutting regime.     

Variation of trace element accumulation by iron-manganese nodules from Dystric Cambisols with and without contamination

Journal of Soils and Sediments - The aim of this study was to characterize the influence of soil contamination on the trace element accumulation in nodules, inter-element relationships inside the...     

An Indigenous Virulent Strain of Erwinia amylovora Lacking the Ubiquitous Plasmid pEA29

ABSTRACT An atypical strain of Erwinia amylovora was isolated near an outbreak of fire blight at a nursery in Spain in 1996. It was obtained from a Crataegus plant showing typical symptoms and was identified as E. amy-lovora by biochemical tests and enrichment-enzyme-linked immuno-sorbent assay, but not by polymerase chain reaction using primers based on the pEA29 sequence. Nevertheless, with primers from chromosomal regions, the isolate gave the expected amplification band. This strain carries one plasmid of approximately 70 kb, with no homology with the 29-kb plasmid common to all pathogenic strains, or with a large plasmid present in some E. amylovora strains. Growth of the strain in minimal medium without thiamine was slower compared with cultures in the same medium with thiamine, a characteristic typical of strains cured of the 29-kb plasmid. Nevertheless, aggressiveness assays on pear, apple, and Pyracantha plants and in immature pear fruit showed that this strain exhibited a virulence level similar to other strains containing pEA29. To the best of our knowledge, this is the first report of the isolation from naturally infected plant material of a pathogenic strain of E. amylovora without pEA29, but with a plasmid of approximately 70 kb not previously described.     

Frequency of Phaeosphaeria nodorum, the Sexual Stage of Stagonospora nodorum, on Winter Wheat in North Carolina

ABSTRACT Ascocarps of Phaeosphaeria nodorum, which causes Stagonospora nodorum blotch (SNB) of wheat, have not been found by others in the eastern United States despite extensive searches. We sampled tissues from living wheat plants or wheat debris in Kinston, NC, each month except June from May to October 2003. Additional wheat samples were gathered in Kinston, Salisbury, and Plymouth, NC, in 2004 and 2005. For the 3 years, in all, 2,781 fruiting bodies were dissected from the wheat tissues and examined microscopically. Fruiting bodies were tallied as P. nodorum pycnidia or ascocarps, "unknown" (not containing spores, potentially P. nodorum or other fungi), or "other fungi." In the 2003 sample, asco-carps of P. nodorum were present each month after May at a frequency of 0.8 to 5.4%, and comprised a significantly higher percentage of fruiting bodies from wheat spikes than of those from lower stems and leaves. Ascocarps also were found at frequencies <10% in some wheat debris samples from 2004 and 2005. Analysis of the nucleotide sequences of internally transcribed spacer regions of 18 genetically distinct North Carolina isolates from 2003 suggested that all were P. nodorum, not the morphologically similar P. avenaria f. sp. triticea. Neither the 18 isolates from 2003 nor a set of 77 isolates derived from 2004 Kinston leaf samples gave reason to suspect a mating-type imbalance in the larger P. nodorum population (P >/= 0.4). We conclude that, in North Carolina, sexual reproduction plays a role in initiation of SNB epidemics and the creation of adaptively useful genetic variability, although its relative importance in structuring this population is uncertain.     

Detection of antibiotic residues and association of cefquinome residues with the occurrence of Extended-Spectrum β-Lactamase (ESBL)-producing bacteria in waste milk samples from dairy farms in England and Wales in 2011

Waste milk samples from 103 farms in England and Wales were examined for the presence of β-lactam antibiotics and ESBL-producing Enterobacteriaceae. Approximately 10 months after the initial sampling, further waste milk, environmental and faecal samples from farms shown to be positive for CTX-M Escherichia coli were investigated further. Isolates with an ESBL phenotype were tested by PCR for the presence of bla_CTX-M, bla_OXA, bla_SHV and bla_TEM genes. Isolates positive for bla_CTX-M were sequenced to determine CTX-M type. Representative isolates were further examined by PFGE, plasmid replicon typing and serotyping. Of particular interest, 21.4% of waste milk samples contained residues of the cephalosporin cefquinome, which was significantly associated with CTX-M bacteria. Such bacteria occurred in 5.8% of the waste milk samples (including 3.9% CTX-M E. coli). CTX-M types identified were 1, 14, 14b and 15, but none of the E. coli were serotype O25, the serotype of the human pandemic strain.     

Yersinia pseudotuberculosis infection in a suckler calf in the United Kingdom: a case report

Enterocolitis caused by Yersinia pseudotuberculosis was identified by bacterial culture and histopathology in a 5-month old suckler calf. No other significant enteric pathogens were detected. Diagnosis of this condition can be missed if selective media are not used for bacteriology and if histopathology is not attempted or the alimentary tract is unsuitable for examination. This is the first case report of Y. pseudotuberculosis infection in a calf in the United Kingdom.     

The Effect of Vitamins on Weight Gain and Organ Production in the Sea Urchin,Lytechinus variegatus (Echinodermata: Echinoidea)

We investigated the requirements for a commercial vitamin premix in diets of Lytechinus variegatus. Small L. variegatus (ca. 28 mm diameter) were collected from Saint Joseph Bay, Florida, and acclimated to laboratory conditions (32 ppt salinity, 22 C, 12:12 photoperiod) for 3 wk, then placed individually into plastic mesh cages (n = 16 per treatment). Sixteen urchins were dissected to obtain initial weights of organs (gut, gonad, test). Each treatment was fed one of five semipurified diets supplemented with levels of a commercial shrimp vitamin premix ranging from 0 to 0.9% dry weight. At 4‐wk intervals, wet weights and test diameters were measured. At 16 wk, urchins were dissected and organs weighed. Significant weight gain and 100% survival was observed with all diets. At 16 wk, urchins fed 0% vitamin premix exhibited no noticeable pathology but had significantly less weight gain than those fed the 0.6% vitamin premix. Those fed the 0.6% vitamin premix had significantly greater weight gain than all other diets (P < 0.0001). Gonad weights increased in all treatments, but did not vary significantly. Under the conditions of this study, L. variegatusexhibited a satisfactory nutritional response. Experiments are planned to determine specific dietary vitamin requirements for L. variegatus.