A follow up study on antibodies against Lawsonia intracellularis in mares and foals from two breeding farms in Germany

Equine proliferative enteropathy (EPE) caused by Lawsonia (L.) intracellularis is an emerging disease in foals, particularly in North America. Since a case report in Germany exists, the objective of this study was to examine the incidence of L. intracellularis-antibodies in healthy horses from two German breeding farms. In group 1, serum samples from 24 (year 1) and 16 (year 2) Haflinger mares and their foals were taken. In group 2, over a period of five months, serum samples of six warmblood mares and foals were collected monthly from birth until the foals became seronegative. Serum samples were tested using an ELISA system. Results are expressed as Percentage of Inhibiton (PI). All adult mares (100%) of both groups were seropositive at each point in time (PI-value > 30). In group 1,7/24 foals (29.2%) in year 1 and 4/16 foals (25%) in year 2 had antibodies.The seropositive foals from year 2 had the same dams as the seropositive foals from year 1. In group 2 five of six foals were seropositive after birth. Antibodies decreased from March to July in mares and foals. In July, all five foals tested negative for the first time between the ages of 82 and 141 days (median 115 days). PI-values of mares were significantly correlated with PI-values of their foals. Higher PI-values were seen in younger foals and early in spring. Loss of antibodies in foals at the age of three to five months could be a risk factor for infection and appearance of EPE.     

Genetic variability of PRRS virus in Austria: consequences for molecular diagnostics and viral quantification

Porcine reproductive and respiratory syndrome virus is a virus with a relatively high level of sequence variation, especially between the European and the American-type strains. This high degree of sequence variations will influence the accuracy of results obtained by molecular diagnostic methods, especially if mutations are located in the primer or probe binding regions of PCR or real-time PCR based assays. In order to provide the basis for the development of an accurate, region-tailored assay we have analysed samples obtained from several Austrian pig herds using a series of RT-PCR assays. Subsequent sequencing of the PCR products from ORF5 and phylogenetic analysis revealed the occurrence of both the European and the American-type of porcine reproductive and respiratory syndrome virus in Austria. Since vaccination with the American-type vaccine is not authorized in Austria the import of vaccinated animals is the most likely explanation for the occurrence of these strains. The study highlights the importance of a detailed study on the sequence variations occurring in the region of interest before the development of a reliable PCR-based assay.     

Photochemical transformation of thiophanate-methyl and thiophanate to alkyl benzimidazol-2-yl carbamates

The systemic fungicides thiophanate-methyl (TPM) and thiophanate (TPE) were transformed in aqueous solutions on glass by irradiation with u.v. and sunlight to the more effective fungitoxic substances methyl benzimidazol-2-yl carbamate (MBC) and ethyl benzimidazol-2-yl carbamate (EBC), respectively. The thiophanate fungicides were not converted when incubated in the dark. The photochemical transformation of TPM and TPE to the corresponding alkyl benzimidazol-2-yl carbamates increased with the exposure time of u.v. irradiation. However, no light catalysed reactions occurred when both fungicides were irradiated with u.v. light in the solid state. The residue of TPM and TPE on leaves of cotton plants following spray application were transformed by the energy of sunlight to the more fungitoxic MBC and EBC.     

Gesundheitsgefährdung durch chemische Pflanzenschutzmittel

Ohne Zusammenfassung     

Measuring forest damage of ungulates: what should be considered

Principles and criteria for the objective assessment of ‘damage' are presented as a basis for objective discussion and to promote targeted research. The topic will be considered from three different viewpoints – theoretical background, silviculture, and nature conservation. Examples of methods to assess ‘damage' are given, as are the criteria and indicators for target values for growing stock.

The objective existence of damage must be established by comparing the current status against a target. Only if the present status no longer permits achievement of the desired target can damage be claimed. The same is true for verification of ‘benefit' resulting from an impact leading to a favorable status. Establishing the degree of browsing damage on forest regeneration allows forecasts of damage to be made, but the actual damage can only be determined at a future time, for example when the timber is harvested or when the function of the forest is seen to have been compromised. The earlier the forecast is made the more uncertain it is, because the compensatory responses of the forest can only be forecast to a limited extent. Silvicultural targets depend on the requirements of both, the forest owner and the public. Main indicators for assessing ungulate damage on forest regeneration are total tree density, species composition, and height structure. From the viewpoint of nature conservation the determination of target values is particularly difficult. The measurement of damage involves choosing the most relevant indicators of favorable condition of woodland habitats and assessing these in the field. With adequate resources this can be done quantitatively using a wide range of standard field measurement techniques. Alternatively, where resources are limited, it can be done qualitatively by scoring different areas for a range of indicators. As yet, such qualitative methods are in their infancy. Specific research is now being undertaken in some European countries.     

Development of ZWIPERO, A Model Forecasting Sporulation and Infection Periods of Onion Downy Mildew based on Meteorological Data

The weather-based forecasting model ZWIPERO was developed by the German Weather Service and determines the risk of sporulation and infection of Peronospora destructor quantitatively based on actual as well as predicted weather data (temperature, relative humidity, leaf wetness, precipitation). The model allows precise planning of disease monitoring and infection-related application of fungicides. ZWIPERO is a more complex mathematical model than the previously published models for downy mildew. In order to operate ZWIPERO independently of the actual field location and season, the time of sunrise and sunset of the location are exactly determined by a subroutine. Another subroutine provides simulated microclimatic input variables based on local production data as well as actual and hourly predicted (up to 4 days) standard weather data. Starting at the time of 'sunrise + 7 h', ZWIPERO calculates the number of sporangia produced, the time of onset of sporangia release, as well as the number of infections possible and the number of sporangia which may survive the day for each 24-h time step. Field evaluations of sporulation periods of downy mildew showed that the simulated micrometeorological input variables are reliable. As the actual plant development, the susceptibility and the disease incidence in the field are not taken into account, ZWIPERO has to be considered primarily as a decision support system for extension services and growers.