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111.
Dr. Joachim Kakau Dorothee Abdel-Kader Petra Müller Karl-Heinz Pastrik Luitgardis Seigner 《Gesunde Pflanzen》2004,56(4-5):111-115
From 1999 to 2001, field trials were carried out to find out weather there is a risk of the causal agent of Bacterial Ring Rot of potato (Clavibacter michiganensis ssp. sepedonicus) to be transmitted to the leaves of healthy potato plants via contaminated machinery and equipment during the vegetation period and if so weather the bacteria are transported into the newly formed tubers. Two methods were chosen. Firstly, a sharp-edged metal bar contaminated with a bacterial suspension was drawn through the leaves of potato plants up to 6 times during the vegetation period. Secondly, a suspension of the pathogen was directly injected into the stems of potato plants. The harvested tubers were tested in all trials, leaves were additionally tested in the trial with the contaminated metal bar. The pathogen was not found in any trial. Therefore the risk for the transmission of the Ringrot agent to the leaves of potato plants with contaminated machinery might be very low. 相似文献
112.
Hewicker-Trautwein M Feldmann M Kehler W Schmidt R Thiede S Seeliger F Wohlsein P Ball HJ Buchenau I Spergser J Rosengarten R 《The Veterinary record》2002,151(23):699-703
During an outbreak of pneumonia and arthritis in beef calves and young cattle on a large farm in north-west Germany, Mycoplasma bovis and Mycoplasma californicum were isolated from tracheobronchial lavage fluids and synovial fluids. The microbiological findings in dead and living animals and the immunohistochemical demonstration of M californicum antigen in lung and arthritic joint tissue, indicated that under poor housing conditions and possibly other predisposing factors, this mycoplasma, like M bovis, can colonise the respiratory tract and may be able to cross the respiratory mucosal barrier to spread through an infected animal and cause systemic infections that may contribute to severe arthritis. 相似文献
113.
Wehebrink T Kemper N grosse Beilage E Krieter J 《Berliner und Münchener tier?rztliche Wochenschrift》2008,121(1-2):27-32
The aim of this study was to determine the prevalence of Campylobacter spp. and Yersinia spp. in a total of 1,040 faecal samples taken from animals at different ages from four farrowing and twelve fattening herds. In the farrowing unit, faeces were collected from 68 sows (faecal samples) and 256 suckling piglets (rectal swab samples). Further samples were collected from 362 growing and 354 finishing pigs (rectal swab samples). Additionally, 56 feed and environmental samples were collected. During the slaughtering process, 122 pigs and their carcasses respectively, were sampled three times. Finally, 86 meat and minced meat samples were taken from 34 retail stores. Campylobacter spp. were isolated in sows (33.8 %), piglets (80.9 %), growing (89.2 %) and finishing (64.7 %) pigs. Yersinia spp. were detected in growing (15.2 %) and finishing (13.3 %) pigs only. After twelve hours of chilling neither Campylobacter spp. nor Yersinia spp. were detected. In raw meat samples, Campylobacter spp. were isolated from one liver sample and Yersinia enterocolitica from two meat samples. Common slaughter techniques and hygiene procedures may be effective tools to reduce the risk of contamination and recontamination of meat products since Campylobacter spp. and Yersinia spp. were found only sporadically in raw meat samples. 相似文献
114.
Hornok S Edelhofer R Joachim A Farkas R Berta K Répási A Lakatos B 《Acta veterinaria Hungarica》2008,56(1):81-88
Blood samples were collected from 330 cats in Hungary in order to evaluate their seroconversion to Toxoplasma gondii and Neospora caninum using the indirect fluorescent antibody test (IFAT). The overall prevalence of toxoplasmosis was 47.6%, the prevalence being 22.4% among urban, 50% among suburban and 61.3% among rural animals. Significantly more cats had high IFAT titres (1:640 to 1:5120) in the countryside. Female cats were more frequently infected with T. gondii than males (53.3% vs. 39.3%), and seropositivity increased with the age of animals. The prevalence (0.6%) and titre (1:40) of antibodies to N. caninum was low. Sixty-two cats were also screened for seroconversion to feline infectious peritonitis (FIP) virus. Higher titres to T. gondii were more frequently detected among FIP-positive cats, but this difference was non-significant due to the small number of cats with concurrent infection. 相似文献
115.
Hermann Stumpe Joachim Garz Wilfried Schliephake Lutz Wittenmayer Wolfgang Merbach 《植物养料与土壤学杂志》2000,163(6):657-662
Investigations carried out at Field F3 of the Halle long‐term fertilization trials using data from 1974 to 1983 showed that with adequate supply of mineral N‐fertilizer soil organic matter (SOM) had no significant effects of yield. Similarly enhanced SOM did not justify a reduction of mineral N (Stumpe et al., 2000). The studies presented here examine the effects of the SOM differences existing after the termination of those trials in 1986 up until 1997 (then mainly differences of hardly decomposable SOM) in comparison to farmyard manuring with enhanced mineral N application (3‐factor‐experiment). As with total SOM, hardly decomposable SOM did not directly affect yields. The effects of FYM treatment observed at lower mineral‐N levels were compensated for by enhanced mineral‐N supply. The direct effect of FYM (40 t ha—1) corresponded to a mineral‐N supply of about 60 kg ha—1 and the residual effect to about 20 kg ha—1. The differences of the C‐content in the soil at the beginning of the present studies continued throughout the experimental period of 12 years. In addition, significant differentiation has been caused by FYM and N fertilization in comparison to unfertilized treatments. The major finding is that differences in SOM content do not lead to yield differences on physically good soils (chernozem‐like soils) if appropriate compensation by mineral‐N fertilization takes place. 相似文献
116.
Changes in the subsoil of long‐term trials in Halle (Saale), Germany,caused by mineral fertilization
Four long‐term mineral fertilization trials (50 years) on a Haplic Phaeozem derived from sandy loess were conducted. Fertilization caused changes to the plough layer (0—25 cm) and to the undisturbed subsoil. Without lime, most remarkable acidification occurred in the plough layer, but only slight effects were evident in the subsoil. Where lime was applied, a considerable amount of Ca‐sulphate was formed. This leached out of the plough layer and accumulated throughout the profile, especially in dry years. Where fertilization was not adequate, there was a substantial contribution of K and P from the subsoil (mainly of its upper parts). Where the supply of these two elements continously exceeded their removal, a distinct increase of available K and P at depths of about 50 cm indicated transfer of both elements to the subsoil. Due to the high fixing capacity of both P and K in layers beneath 50 cm, leaching out of the rooting zone can be ignored. Mg and especially Na, applied with some of the fertilizers, were more mobile than K. 相似文献
117.
Fate of 15N after one single application of labelled N fertilizer in the long-term experiment Eternal Rye Cropping Halle To elucidate the fate of N in the long-term field experiment with continuous rye cropping in Halle, Germany (Haplic Phaeozem derived from sandy loess; mean annual precipitation: 466 mm) micro plots (9 m2) were established within the NPK main plot in 1993 and 1994 and the routine N dose (60 kg N ha—1 a—1) was once applied as 15N labelled fertilizer. In the subsequent four years each micro plot was analyzed for the 15N withdrawn with grain and straw and that remaining in the soil after harvest. Parallel to this, micro plots on the unfertilized main plot received a single dose of 5 kg ha—1 of high-label 15N in order to achieve labelling of the annual N input from the air (˜40 kg ha—1 a—1) and to follow its fate. — In the NPK treatment about one third of the labelled fertilizer N applied (= *N) was taken up by the rye in the first year, while nearly half of it remained in the soil (0—100 cm), and 10—15% was not recovered (most likely lost via leaching). During the following three years the amount of *N remaining in the soil decreased from 32.7 kg ha—1 to 21.5 kg ha—1. However, less than half of the remobilized *N had been taken up by the crop. On the unfertilized plot the uptake of *N was lower at the end of the experiment compared to the NPK plot, while the loss exceeded the comparative figure correspondingly. 相似文献
118.
Journal of Plant Diseases and Protection - Apple scab prediction is based on the model of Mills which describes the risk of Venturia inaequalis infection using leaf wetness duration and air... 相似文献
119.
The efficiency of symbiotic dinitrogen (N2) fixation in Vicia faba L. in combination with 3 different Rhizobium leguminosarum strains was studied in a pot experiment during vegetative and reproductive growth. The objective of the experiments was to assess variability among Rhizobium strains inoculated on single legume species and determine possible reasons for observed variations. Dry matter formation, N2 fixation and the carbon (C) costs of N2 fixation were determined in comparison with nodule free plants grown with urea. Nodule number and the capacity of different respiratory chains in the nodules were also measured. The plants inoculated with the Rhizobium strain A 37 formed less dry matter and fixed less N compared to the other two Rhizobium strains (Vic 1 and A 150). This coincided with a lower number of nodules and higher C costs of N2 fixation. The C costs for N2 fixation were in all cases significantly lower during reproductive growth compared to vegetative growth. Neither the latter nor the differences in C expenditure for N2 fixation between the Rhizobium strains could be explained in terms of differences or shifts in the capacity of different respiratory chains in the nodules. 相似文献
120.
世界有机农业发展的历史回顾与发展动态 总被引:20,自引:0,他引:20
简要回顾了世界有机农业的发展历程。将世界有机农业的发展历程分为产生、扩展和增长3个阶段,介绍了各阶段的代表人物和思想。从有机农业的面积、占耕地比例和有机产品的市场状况,综述了世界有机农业的发展动态,并讨论了世界有机农业进一步发展存在的主要问题。简述了中国有机农业的发展动态、问题和对策。 相似文献