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1.
A.J.A. Vinten D.R. Lewis D.R. Fenlon K.A. Leach R. Howard I. Svoboda I. Ogden 《Soil Use and Management》2002,18(3):223-231
Abstract. Slurry from farm animals may contaminate water supplies, rivers and bathing waters with faecal coliforms, such as Escherichia coli . Where animals harbour the O157 strain the hazard to human health is particularly high, but both the hazard level, and the low incidence and sporadic nature of the excretion of E. coli O157 make it difficult to study this strain under field conditions. The survival of total E. coli and of E. coli O157 were compared in the laboratory for two soils under controlled temperature and moisture. E. coli O157 die-off rate was the same as or quicker than for total E. coli . This result meant that field experiments studying the fate of total E. coli should give a satisfactory evaluation of the risk of water contamination by the O157 strain. In four field experiments at three sites, slurry containing total E. coli numbers of 2.2 × 104 to 5.7 × 105 colony forming units per mL (c.f.u. mL–1 ) was applied to drained field plots. Field die-off was faster than expected from laboratory experiments, especially in one experiment where two weeks dry weather followed application. In all but this experiment, the first drain flow events after slurry application led to very high E. coli concentrations in the drains (103 to 104 c.f.u. mL–1 ). E. coli O157 was present in the slurry used for two of the experiments (33 c.f.u. per 100 mL in each case). However the proportion of E.coli O157 was very low (about 1 in 105 ) and it was not detected in the drainage water. After the first week E. coli drainage water numbers decreased rapidly but they were 1–10 c.f.u. mL–1 for much of the sampling period after slurry application (1–3 months). 相似文献
2.
Characteristics and host range of tomato powdery mildew 总被引：4，自引：0，他引：4
The anamorphic state of a powdery mildew, which first appeared on tomato in the UK in 1987, currently listed as Erysiphe orontii (anamorph Oidium violae ), was examined microscopically on both tomato and alternative hosts. Host range studies were also carried out. In 1993–95, species and cultivars of plants from 26 of the 30 families listed as hosts of E. orontii were inoculated with tomato powdery mildew in the glasshouse and assessed for susceptibility on a 0–3 scale based on degree of sporulation and growth. Thirteen families contained species or varieties that were susceptible and a total of 80 varieties, including many economically important Cucurbitaceae and Solanaceae, supported sporulation to some extent (susceptibility score 1–3). Necrosis was not a constant feature of plants exhibiting resistance, as it could accompany sporulation on some susceptible varieties. Microscopic measurements showed that conidial size, conidiophore length, conidiophore foot-cell length and width, and the number of cells distal to the foot-cell were remarkably constant between samples of powdery mildew taken from tomato each year and from the various alternative hosts. Based on the production of conidia singly, the presence of nipple-shaped to moderately lobed appressoria, and occurrence of straight conidiophores, it is concluded that this fungus on tomato should more correctly be named Oidium lycopersicum until the sexual stage is discovered. The highly polyphagous nature of this powdery mildew would suggest that it represents a potential risk to UK agriculture and horticulture, but the failure to recover any powdery mildew from 120 samples of potato, including varieties Cara and Maris Piper, on which the tomato powdery mildew could sporulate in the glasshouse, suggests that environmental factors may play a key role in preventing establishment of this powdery mildew on alternative hosts on a commercial scale in the field. 相似文献
3.
Crane M Norton A Leaman J Chalak A Bailey A Yoxon M Smith J Fenlon J 《Pest management science》2006,62(1):5-19
EU Directive 91/414/EEC requires there to be no unacceptable effects on the environment from the use of pesticides. This paper reports the views of direct stakeholder groups and results from an opinion survey of more than 2000 members of the general public on what in practice should constitute acceptable and unacceptable effects of pesticides. Stakeholders in focus groups were concerned with the potential effects of pesticides on animal and plant population viability and micro-organism function but recognized that a trade-off exists between the potential economic advantages of responsible pesticide use and the potential disadvantages of individual poisoning events. The public opinion survey showed that although pesticides are widely used in homes and gardens, their use on farm crops remains of concern to the public. Concerns are greatest on issues of human health and food quality but potential environmental effects are also an issue for a substantial number of people, particularly if attractive species could be affected. 相似文献
4.
Wendy M. Squires F. A. Langton J. S. Fenlon 《The Journal of Horticultural Science and Biotechnology》2013,88(6):661-671
The transplantation phase of narcissus micropropagation was studied using bulbils from bulbing shoots sub-cultured to hormone-free bulbing medium. Transplantation success was enhanced by the incorporation of activated charcoal in the medium, culturing the shoots at a constant 20°C and subjecting bulbils to a period of cold storage at 5°C to overcome dormancy prior to planting out. These measures gave overall figures for transplantation success in a large-scale evaluation experiment of 47.8-81.2% depending on cultivar. Greatest success was achieved using bulbils weighing more than 0.2 g. However, the overall proportion of such bulbils was only 0.19 to 0.20. Early leaf senescence, which limits bulbil growth in culture, appeared to be linked with initial bulbing shoot weight. The beneficial effects on transplantation of using full-strength mineral salts over halfstrength salts and of using one particular clone of cv. St. Keverne, were probably mediated via effects on final bulbil weight. Elevated concentrations of sucrose in the bulbing medium gave no benefit even though final bulbil weight was increased. High sucrose levels gave earlier shoot senescence and increased dormancy. Culture of bulbils in darkness did not effect final bulbil weight but was extremely detrimental to transplantation success. Most unsuccessfully transplanted bulbils showed a foliar growth phase suggesting a premature re-entry into dormancy. With few exceptions, bulbils judged to have been successfully transplanted grew on without problem in their second year. 相似文献
5.
S.R. Adams V.M. Valdeés C.R.J. Cave J.S. Fenlon 《The Journal of Horticultural Science and Biotechnology》2013,88(3):368-373
SummaryExperiments in glasshouse and controlled environment facilities investigated the effect of different fruit removal and lighting/shading treatments on the pattern of tomato yields. While the removal of flowering trusses resulted in a yield loss about eight weeks later, there was little loss in cumulative yield as assimilates were distributed to neighbouring trusses. In the growth room experiment, increased photosynthetic photon flux density (PPFD) for one week resulted in a period of increased yield from 4–6 weeks after the start of the treatment, followed by suppressed yields due to smaller fruits on subsequent trusses. However, neither fruit load nor assimilate availability appeared to be responsible for the fluctuations in yield recorded within the glasshouse crop. In this experiment fruit size remained fairly consistent (except when fruit removal treatments were applied), whereas the number of fruits picked per week exhibited much greater variability. This was the case even when all trusses were pruned to leave five fruits, and so was not due to a cycle in the number of fruits set per truss. The flushes in yield were found to be a consequence of a hastening of fruit maturation. 相似文献
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7.
An outbreak of LI infection in a group of free range horses is described. Three of 4 horses displayed signs of CNS disturbance and 2 of these died after illnesses ranging from 2-12 days duration. In both cases a variable degree of viral polioencephalomyelitis was observed. A virus antigenically indistinguishable from a reference strain of LI virus was isolated from the brain and cervical cord of a 3 y.o. draft mare. Serum samples obtained from 3 of the horses contained HI, CF, precipitating and neutralising antibodies to LI virus, with a rise in antibody titre being demonstrated in 2 animals. 相似文献
8.
A meta‐analysis was undertaken of 51 comparisons of standard polyethylene film with oxygen barrier (OB) film in covering systems for bunker silos, unwalled clamp silos and bales. Mean losses of DM or OM during storage from the top 10 to 60 cm of bunker and clamp silos were 195 g kg?1 for standard film and 114 g kg?1 for OB film systems (41 sets of data, P < 0·001), while mean total losses of DM from baled silage were 76·8 g kg?1 for standard film and 45·6 g kg?1 for OB film systems (10 sets of data, P < 0·001). Top surface silage judged subjectively to be inedible was 107 and 29·6 g kg?1 for standard film and OB film systems respectively (5 sets of data, P = 0·02). Aerobic stability was 75 h for silage stored under standard film system and 135 h for silage stored under OB film system (11 sets of data, P = 0·001). It is concluded that the OB film system reduces losses from the outer layers of silos and from bales and increases the aerobic stability of silage in the outer layers of silos. 相似文献
9.
Listeria monocytogenes contamination is associated with silage that has been subjected to aerobic deterioration. A laboratory ensiling system based on plastic tube silos, which permit aerobic spoilage to take place in a controlled manner, is described. This system gives a high degree of consistency between replicates. Parameters measured over a 90-d ensiling period were pH, L. monocytogenes and Enterobacteriaceae counts and percentage spoilage. The system may be suitable for assessing the effectiveness of additives on parameters, such as aerobic spoilage and L. monocytogenes , which are not easily measurable in field studies. The study confirmed the relationship between the presence of Listeria spp. and Enterobacteriaceae in aerobically spoiled silage, showing that the latter group of bacteria may be useful as indicators of the potential risk of L. monocytogenes contamination of silage. 相似文献
10.
Rapid quantitative assessment of the distribution of Listeria in silage implicated in a suspected outbreak of listeriosis in calves 总被引：11，自引：0，他引：11
D R Fenlon 《The Veterinary record》1986,118(9):240-242
A silage clamp was sampled for the presence of Listeria species. Even though covered by a heavy duty black plastic sheet the top few centimetres of silage were heavily contaminated with Listeria species. In the areas nearest the edges of the sheet the pathogenic species Listeria monocytogenes was found in numbers in excess of 12,000 organisms/g silage. Using the methods of isolation described, pathogenic species of Listeria could be differentiated from non-pathogenic species in three to four days. 相似文献