Biological control of Fusarium oxysporum f. sp. lycopersici     

A. DE  CAL  S. PASCUAL  I. LARENA  P. MELGAREJO 《Plant pathology》1995,44(5):909-917

Fungi known to produce lytic enzymes were used in an attempt to control wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici (FOL). Some of the fungal species (Penicillium oxalicum, Penicillium purpurogenum and Aspergillus nidulans) damaged hyphae of FOL in vitro and reduced the numbers of microconidia in the soil. Treatments with fungi did not result in a reduction in either chlamydospores of FOL in soil or populations of FOL in the rhizosphere of tomato. P. oxalicum was the most effective agent of biocontrol, and it reduced disease severity in both non-autoclaved (20% decrease) and sterile soil. In sterile soil, P. oxalicum reduced disease with different levels of severity (27% decrease at high levels and 50% decrease at low levels). Disease control by A. nidulans and P purpurogenum was only achieved when disease severity was low in sterile soil (55% and 45%, respectively).  相似文献   

Biological diversity of citrus tristeza virus (CTV) isolates in Spain   总被引：5，自引：1，他引：5  

J. F. BALLESTER-OLMOS  J. A. PINA  E. A. CARBONELL  P. MORENO  A. HERMOSO DE  MENDOZA  M. CAMBRA  L. NAVARRO 《Plant pathology》1993,42(2):219-229

A survey of citrus tristeza virus (CTV) isolates was carried out in most citrus-growing areas in Spain. Twenty-two isolates were selected by geographical origin, cultivar of source tree, and symptoms observed on the host or in preliminary tests, and were biologically characterized.
A wide range of variation in transmissibility by aphids and symptom intensity on nine different indicator species or scion-rootstock combinations was observed among CTV isolates. Mexican lime. Citrus macrophylla , and to a lesser extent citron were the most useful hosts for characterizing these isolates, and leaf symptoms and stem pitting were the most discriminating traits. Positive correlation was observed between symptoms induced on Mexican lime and C. macrophylla , but not between the symptoms induced on these indicators under greenhouse conditions and the homologous symptoms on plants grown in the screenhouse. Some of the traits studied enabled us to establish relatively well-defined groups of isolates, but in most cases a continuous range of variation was obtained and no clear group could be defined.  相似文献   

Windborne spread of ergot disease (Claviceps africana) in sorghum A-lines in Zimbabwe     

D. E. FREDERICKSON  P. G. MANTLE  W. A. J. DE  MILLIANO 《Plant pathology》1993,42(3):368-377

Ergot disease spread rapidly in Zimbabwe amongst replicated plots of male-sterile sorghum A-lines, from a group of centrally situated and precociously inoculated plants. Prominent secondary conidiation by the pathogen, Claviceps africana , on the surface of exuded honeydew provided airborne spores which were trapped in a Burkard continuous spore trap and showed diurnal peaks of concentration in air close to the primary source of inoculum. The rate of disease spread ( r =0·2; range 0·14–0·58) closely matched that recorded for other plant pathogens such as Phytophthora infestans and Puccinia graminis tritici , and it is concluded that the characteristic secondary conidia of C. africana were the principal epidemiological agents within the experimental area. Ergot spread by windborne secondary conidia has significant epidemiological and economic implications for sorghum hybrid breeding in southern Africa.  相似文献   

Racial diversity and complexity in regional populations of Erysiphe graminis f.sp. hordei in France over a 5-year period   总被引：2，自引：3，他引：2  

D. ANDRIVON  C. DE  VALLAVIEILLE-POPE 《Plant pathology》1993,42(3):443-464

The evolution of race patterns in three French regional populations of the barley powdery mildew pathogen Erysiphe graminis f.sp. hordei over a 5-year period showed rapid adaptation to newly introduced host resistance genes. In all three regions, the main change consisted of the replacement of initially abundant races by pathotypes differing markedly from them by their virulence gene combinations. This explained the increase in diversity during the first 3 years of the survey, when the second group of pathotypes became more common in the populations, and its subsequent decrease due to the decline of the first group of races. The mean number of virulence genes per isolate did not vary noticeably over time in the three populations, remaining at about four out of 12 genes tested. However, the distribution of the isolates into virulence complexity classes was greatly modified, fitting a binomial distribution by the end of the study, although significant deviations were apparent in the first 2 years (1986 and 1987). The data indicate that selection, migration and recombination are the most important factors shaping race structure and evolution in powdery mildew populations, and that mutation is of limited significance. No convincing evidence was obtained for the existence of stabilizing selection sensu Vanderplank as the mechanism limiting virulence complexity. Implications regarding spatial and temporal deployment of race-specific resistance genes to control powdery mildew are discussed.  相似文献   

Drying off cows: a comparative study with two dry cow products     

Sampimon OC  Vernooij JC  Sol J 《Tijdschrift voor diergeneeskunde》2003,128(16):474-480

From September 1998 to September 1999, at drying off 397 cows on 73 Dutch farms were treated, with two antibiotic containing dry cow products (cloxacillin; penicillin-neomycin). Farms and cows were selected on an increased bulk milk somatic cell count (BMSCC) and individual cow somatic cell count. The objective of the trial was to compare the efficacy of both products under field conditions. Both products proved to be highly effective against streptococci and penicillin sensitive staphylococci. Because of the low incidence of infections caused by Escherichia coli and penicillin resistant staphylococci no conclusions could be drawn on differences in activity for these two pathogens. No significant differences were found between the two products in cure rate of existing infections at drying off, incidence of new infections during the dry period, incidence of clinical mastitis during the dry period and the course of the individual cow cell counts during the trial.  相似文献   

Effect of preculture freezing and incubation on bacteriological isolation from subclinical mastitis samples     

Sol J  Sampimon OC  Hartman E  Barkema HW 《Veterinary microbiology》2002,85(3):241-249

In this study the sensitivity of three methods of isolation of udder pathogens from milk samples from subclinical mastitis cases was compared. For analysis 1827 quarter milk samples were selected. Milk was cultured using a standard culture technique (0.01 ml of fresh milk streaked on a sheep blood agar plate and on Edward's medium). In addition, an inoculum of 0.01 ml of the original milk sample was incubated for 24h at 37 degrees C in broth, followed by culture using the standard culture technique. In the third method, the whole milk sample was frozen for 24h, and then incubated for 24h at 37 degrees C, followed by culture using standard culture technique. The isolation percentage of Staphylococcus aureus was 4.7% for standard culture technique, 14.2% for incubation in broth, and 21.5% for the combination of freezing plus incubation. Isolation percentage of Streptococcus dysgalactiae and Streptococcus agalactiae was highest using the standard culture technique, while isolation rate of Streptococcus uberis was not different among the three methods used. With increasing somatic cell count, the likelihood of S. aureus, S. dysgalactiae and S. uberis isolation increased.Based on the relative sensitivity, defined as the isolation rate using a single technique compared to the isolation rate of the three techniques together, a combination of standard culture technique and freezing plus incubation was most attractive for achieving a high isolation rate of S. agalactiae and S. dysgalactiae. Relative sensitivity of S. uberis isolation was highest using the standard culture technique and incubation in broth, while S. aureus was most often isolated using a combination of incubation in broth and freezing plus incubation. A combination of the three methods increased the isolation rate for S. dysgalactiae, S. uberis and S. aureus. The standard culture technique, together with the combination of freezing plus incubation, can be recommended for isolating major udder pathogens. If S. aureus is the pathogen of main interest, using incubation in broth together with the combination of freezing plus incubation performed best.  相似文献   

COMPUTED TOMOGRAPHIC QUANTIFICATION OF CANINE ADRENAL GLAND VOLUME AND ATTENUATION     

GIOVANNA BERTOLINI  TOMMASO FURLANELLO  DAVIDE DE LORENZI  MARCO CALDIN 《Veterinary radiology & ultrasound》2006,47(5):444-448

We conducted a retrospective study in presumed normal dogs to determine the adrenal gland attenuation and volume values. Multidetector computer tomography (MDCT 16) analysis of the gland was carried out in 48 adult dogs without evidence of adrenal gland disease that underwent CT examination for acute spinal injuries. The mean nonenhanced attenuation value +/- SD of the left adrenal gland was 36.0 +/- 5.3 HU (range: 22.0-42.0 HU). The mean nonenhanced attenuation value +/- SD of the right gland was 34.3 +/- 7.0 HU (range: 20.4-48.6HU). The mean enhanced attenuation value +/- SD were: left gland 101.5 +/- 10.6HU (range: 86.8-128.0 HU), and right gland 97.4 +/- 12.4 HU (range: 58.9-123.6 HU). The mean CT volume +/- SD were: left gland was 0.60 cm3 (range: 0.20-0.95; SD 0.17), and right gland (0.55cm3, range: 0.22-1.01; SD 0.19). Attenuation values and volume data were related to age, weight, and gender, using ANOVA. There was no statistically significant difference between the left and right side or in adrenal measurements, because of body weight class effects. The animal effect was the most important source of variation for all adrenal measurements. Based on our study, CT is an effective method for assessing adrenal characteristics in the dog. Normative CT data are provided to allow estimation of normal adrenal gland size and volume.  相似文献   

ECHOCARDIOGRAPHIC REFERENCE VALUES IN WHIPPETS   总被引：1，自引：0，他引：1  

VALÉRIE BAVEGEMS  LUC DUCHATEAU  STANISLAS U. SYS  RÉ DE RICK 《Veterinary radiology & ultrasound》2007,48(3):230-238

The aim of the study was to establish reference echocardiographic values for whippets, to compare these values with previously published reference values for the general dog population, and to determine whether there is an influence of gender and breeding lines on echocardiographic measurements. Echocardiographic parameters from 105 apparently healthy whippets without cardiac symptoms were used to establish reference values for the breed and to compare these values with two previously reported reference ranges. The coefficients of the allometric equation Y= aM(b), useful to reconstruct normal M-mode and two-dimensional average values for whippets of varying weights, were calculated, as well as the lower and upper limits of the 95% prediction interval. First, we found that whippets have a significantly larger left ventricular diameter, increased left ventricular wall, and interventricular septum thickness than expected, in diastole as well as in systole. Fractional shortening was significantly lower than the reference value. Second, comparing males and females, taking body weight differences into account, females had a significantly larger left ventricular diameter in diastole and systole. Minor differences were found between racing and show pedigree dogs. In conclusion, the results of this study confirm that breed-specific reference values are needed in echocardiography. In whippets, the values found in this study can be used as references in order to avoid overinterpretation of cardiac dilation, hypertrophy, and/or decreased contractility in these dogs.  相似文献   

DOPPLER ULTRASONOGRAPHIC ESTIMATION OF RENAL AND OCULAR RESISTIVE AND PULSATILITY INDICES IN NORMAL DOGS AND CATS     

ROSA NOVELLAS  YVONNE ESPADA  RAFAEL RUIZ DE GOPEGUI 《Veterinary radiology & ultrasound》2007,48(1):69-73

Resistive index (RI) and pulsatility index (PI) are indirect measurements of blood flow resistance that may be used to evaluate vascular changes in renal and ophthalmologic diseases. To our knowledge, no reports are available describing values for renal and ocular PI index in the unsedated dog and ocular RI and PI indices in the unsedated cat. The purpose of this study was to measure normal values for both intrarenal and ocular RI and PI within the same subject in unsedated clinically normal dogs and cats. Twenty-seven dogs and 10 cats were considered healthy by means of physical examination, CBC, biochemical profile, urinalysis, and ultrasonography. Systolic blood pressure was measured by Doppler ultrasonography. Intrarenal and ocular arteries were scanned by pulsed Doppler ultrasonography to calculate RI and PI. No significant differences were noted between the values obtained for the right vs. the left kidney and eye. The upper values of these indices were calculated as mean+2 standard deviations resulting in 0.72 and 1.52 for dog renal RI and PI; 0.7 and 1.29 for cat renal RI and PI; 0.76 and 1.68 for dog ocular RI and PI; and 0.72 and 1.02 for cat ocular RI and PI.  相似文献   

Cellulase Supplementation Does Not Improve the Digestibility of a High-Forage Diet in Horses     

C.I. O''Connor-Robison MS  B.D. Nielsen MS  PhD  R. Morris BS 《Journal of Equine Veterinary Science》2007,27(12):535-538

Six mature Arabian geldings were used in a two-period crossover study to investigate the effects of cellulase supplementation on fiber digestion. Horses were randomly assigned to either a control (CO; n = 3) or a cellulase (CE; n = 3) treatment for the first period and then treatments were switched for period 2. Each period consisted of a 10-day diet adaptation followed by a 3-day total fecal collection. The enzyme mixture contained 40,000 cellulase units/g and was fed at a rate of 3 g/day split evenly between two feedings. During the diet adaptation period, horses had ad libitum access to timothy hay and were also fed 165 g whole oats as a carrier for the supplement. When eating the CO treatment, horses consumed 16% more hay than when on the CE treatment (P = .004). Fecal output also tended to be greater when horses consumed the CO treatment as compared with CE treatment (P = .07). No differences were found between treatments for fecal percent dry matter (DM%), fecal neutral detergent fiber (NDF), fecal acid detergent fiber (ADF), fecal nitrogen (N), or fecal gross energy (GE). There was a trend for horses consuming the CO treatment to digest more NDF than when consuming the CE treatment (34.6% ± 1.5 vs 31% ± 1.5; P = .07). Horses also digested a greater %ADF, %N, and Mcal of energy when consuming the CO treatment than when consuming the CE treatment (P < .05). Cellulase addition to a hay-based horse diet decreased digestion of fiber components.  相似文献