Foot and mouth disease and bluetongue: differences and similarities

On 26th of july 2007 a new case of bluetongue was notified in the Netherlands and on 2nd of august 2007 foot-and-mouth disease was diagnosed in Surrey, England, which raised the threat of having both infections simultaniously in one area. Bluetongue and foot-and-mouth disease have a different pathogenesis, but symptoms may resemble each other at a later stage of infection. The pathogenesis and possible clinical symptoms of both infections are discussed and illustrated with pictures.     

Salvinia plants in trade: what species are we actually talking about?

Incorrect labelling of plants in trade and misidentification are widespread. Likewise, in trade numerous names are being used for the ornamental aquatic plant known as ‘Kariba weed’, but rarely the correct scientific name Salvinia molesta Mitch. For inspection services of EPPO member countries, correct identification of S. molesta has become important since the species was added to the EPPO A2 List and the List of Union concern in accordance with EU regulation 1143/2014 based on an EPPO Pest Risk Analysis (PRA) for the species. Inspections and a targetted survey of Salvinia plants in trade in the Netherlands were performed and additional material was obtained from wild sources in South Africa, Hungary and the United States. Specimen identification was verified by comparison with the herbarium collection at Naturalis Biodiversity Center in Leiden and with the sequences available in NCBI GenBank database. This paper provides the tools to correctly identity the relevant Salvinia species.     

Water requirement of Aloe vera in a dry caribbean climate

Summary As hardly any data can be found on the water requirement and yield response to water of Aloe vera, an irrigation experiment on transplanted aloe poles was conducted on the Caribbean island of Aruba. Compared to non-irrigated treatments irrigation shows a positive influence on growth, number of developed leaves, raw gel figure and gel production per plant. The amount of irrigation water to apply can be best calculated based on crop coefficients (K_c) between 0.20 and 0.30. Treatment based on a K_c value higher than 0.30 did not further increase production. A lysimeter study conducted over a relatively short period revealed that the crop coefficient for Aloe vera varied between 0.25 and 0.40 which is characteristic of the so-called agave/pineapple group.     

Analysis of the uncertainty associated with the estimation of nitrogen losses from farming systems

This work describes the analysis of the uncertainty linked to the annual direct and indirect losses of different nitrogenous compounds at the scale of a group of farms. The nitrogen (N) forms taken into account are: ammonia (NH₃), nitric oxide (NO), nitrous oxide (N₂O), dinitrogen (N₂) and nitrate (NO₃). The gaseous N emissions for the different components of the farms are estimated with a selection of adapted emission factors. The NO₃ losses at the farm scale are calculated as the difference between the surplus of the farm-gate N balance and the gaseous N emissions.     

Effect of salinity on water stress, growth, and yield of maize and sunflower

Maize and sunflower were grown in tanks filled with loam and clay, and were irrigated with water of three different levels of salinity. Predawn leaf-water potential and stomatal conductance were used as parameters for water stress. The predawn leaf-water potential of maize was higher than that of sunflower, but the effect of salinity and soil texture on the predawn leaf-water potential was the same for both crops. The stomatal conductance of sunflower was much higher and more severely affected by salinity and soil texture than the stomatal conductance of maize.

Although salinity had a more serious effect on the development of leaf area and canopy dry matter of sunflower, its effect on evapotranspiration and grain yield was the same for both crops. Soil texture had a stronger effect on the development of leaf area and canopy dry matter of sunflower, which also appeared in the evapotranspiration and grain yield, indicating that sunflower is more sensitive to drought than maize.     

Finding niches for whole-farm design models – contradictio in terminis?

Whole-farm design models quantitatively analyze the effects of a variety of potential changes at the farm system level. Science-driven technical information is confronted with value-driven objectives of farmers or other social groupings under explicit assumptions with respect to exogenous variables that are important drivers of agricultural systems (e.g., market conditions). Hence, farm design is an outcome of objective specification and the potential of a system. In recent publications, whole-farm design modelling has been proposed to enhance (farm) innovation processes. A number of operational modelling tools now offers the opportunity to assess the true potential of whole-farm design modelling to enhance innovation. In this paper, we demonstrate that it is not trivial to find niches for the application of goal-based farm models. Model outcomes appeared not to match questions of farm managers monitoring and learning from their own and other farmers’ practices. However, our research indicates that whole-farm design modelling possesses the capabilities to make a valuable contribution to reframing. Reframing is the phenomenon that people feel an urge to discuss and reconsider current objectives and perspectives on a problem. Reframing might take place in a situation (i) of mutually felt dependency between stakeholders, (ii) in which there is sufficient pressure and urgency for stakeholders to explore new problem definitions and make progress. Furthermore, our research suggests that the way the researcher enters a likely niche to introduce a model and/or his or her position in this niche may have significant implications for the potential of models to enhance an innovation process. Therefore, we hypothesize that the chances of capitalizing on modelling expertise are likely to be higher when researchers with such expertise are a logical and more or less permanent component of ongoing trajectories than when these researchers come from outside to purposefully search for a niche.