Karpography: a generic concept of quality for chain analysis and knowledge transfer in supply chains

As with other areas of science, supply chain analysis suffers from the fact that practitioners of its different component disciplines often find it exchange results and methods of analysis. For fresh produce supply chains a key issue is how to unite the elegant mathematical work on the physiology of quality change with the more qualitative methods of social science that are applied to the analysis supply chain management. This paper explores the possibility of utilising approaches which are widely used in demography to unify concepts of quality modelling and supply chain efficiency in the fresh produce sector. A key feature of demographic (or karpographic) models is that they use the average properties of individuals to model the behaviour of cohorts (or batches) and thus have a direct means of including biological variance within their scope. We illustrate the potential of matrix projection models to provide a simple way to unite mathematical analyses of keeping quality and subjective and qualitative analyses of supply chain efficiency. Among other results, the paper demonstrates a rational basis for the assumption, which has been adopted in recent policy changes to the EU food and agriculture policy, that short (or local) supply chains are, ceterus paribus, superior to longer ones. The analytical approach suggested spans the gap between theoretical modelling and knowledge transfer in a single step and requires no more to allow parameterisation than the elicitation of subjective probability estimates from supply chain participants on the transition of produce from one quality class to another.Quality, modelling, matrix model, variance, supply chain, probability, Agribusiness,

A diffusion model for the adoption of agricultural innovations in structured adopting populations

We introduce a new model for examining the dynamics of uptake of technological innovations in agricultural systems, using the adoption of zero-till wheat in the rice-wheat system in Haryana state, India, as a case study. A new equation is derived which describes the dynamics of adoption over time and takes into account the effect of aggregation (e.g. on a spatial and/or cultural basis) in the adopting population on the rate of adoption. The model extends previous phenomenological models by removing the assumption of homogeneity in the non-adopting fraction of the population. We show how factors affecting the per capita rate of adoption can be captured using cognitive mapping and simulate the dynamics of the adoption process.Bass curve, adoption, innovation, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Aspects of the biology of Brassica/Alternaria host/pathogen systems

The main purpose of this study was to further an understanding of host-pathogen interactions and th e role of phytotoxins in the host relationships of Altemaria brassicae(Berk.) Sacc. and Alternariabrassicicola(Schw.) Wilts., using microscopical, biochemical, and statistical approaches. A further aim was to assess the taxonomic positions of A.brassicae and A.brassicicola within the Altemaria along with their attributes and behaviour patterns in relation to other members of the anamorph-genus.OOn the leaf surfaces of host plants A.brassicae and A.brassicicola showed broadly similar patterns of development but with some features which distinguished them. T he larger spores of A.brassicae typically produced two to three germ -tubes whereas A.brassicicola gave rise to only one. A.brassicae generally produced m ore extensive extra-matrical growth with hyphal branching and appressoria in intercalary as well as terminal positions; hyphae of A.brassicicola produced very few branches and usually terminated in appressoria. For both fungi appressoria were formed most frequently near to or over anticlinal walls of epidermal cells. Smaller numbers of appressoria were formed over periclinal walls and, in the case of A.brassicae, over stomata. The extra-matrical development of both species was m ore or less similar on contrasting host leaf surfaces, although A.brassicae showed somewhat reduced germ -tube numbers and stomatal penetrations on leaves with a pronounced waxy bloom. M arked differences in behaviour on different hosts or between hosts and non-hosts were evident only after penetration. In the case of A.brassicae unsuccessful penetrations were associated with only localised deposition of callose in the cell wall of the challenged cell, while with A.brassicicolaun successful penetration events were associated with cell wall responses which occurred in whole single cells.In comparing A.brassicae and A. brassicicola with other Altemaria species varying in their host range and degree of parasitism, all exhibited essentially similar patterns of extra-matrical behaviour on leaves, culminating in the formation of appressoria. Distinctive host relationships were evident only in the post-penetration phase.From successful penetrations A.brassicae produced a short sub-cuticular phase whereas A.brassicicola appeared to penetrate to intracellular position in the epidermis. Subsequent colonisation involved intercellular hyphal growth and extensive callose formation in host cell walls in response to both species.Biochemical studies on different Altemaria species indicated that each produced a diverse range of metabolites which may exhibit fungitoxic and phytotoxic activity. In the present study cytotoxicity of the extracts was low. T he studies failed to identify host-specific phytotoxicity, as only crude extracts were used, but the critical role of a host specific toxin, or resistance suppressor, is postulated in the initial establishment of infection.In considering genetical variation within A.brassicae and A.brassicicola, there is little evidence of marked physiological specialisation in either species. However, in testing a small number of isolates against a dicarboximide fungicide, A.brassicae showed slight and A.brassicicola showed marked intraspecific variation in fungicide insensitivity. In testing for sensitivity to fungicides the isolates of A.brassicae used w ere found to exhibit distinctive colony growth characteristics.Multivariate statistical techniques were applied to morphological, biochemical, and pathogenic characters to examine phylogenic relationships between selected species of Altemaria.Studies of the taxonomic relationships of the Altemariaspecies are constrained by the absence of teleomorphs, but certain genera within the Pleosporaceae are suggested to accommodate this group of toxigenic, leaf spotting, facultative parasites / saprophytes

Characterization of Pathogen Airborne Inoculum Density by Information Theoretic Analysis of Spore Trap Time Series Data

In a previous study, air sampling using vortex air samplers combined with species-specific amplification of pathogen DNA was carried out over two years in four or five locations in the Salinas Valley of California. The resulting time series data for the abundance of pathogen DNA trapped per day displayed complex dynamics with features of both deterministic (chaotic) and stochastic uncertainty. Methods of nonlinear time series analysis developed for the reconstruction of low dimensional attractors provided new insights into the complexity of pathogen abundance data. In particular, the analyses suggested that the length of time series data that it is practical or cost-eective to collect may limit the ability to definitively classify the uncertainty in the data. Over the two years of the study, five location/year combinations were classified as having stochastic linear dynamics and four were not. Calculation of entropy values for either the number of pathogen DNA copies or for a binary string indicating whether the pathogen abundance data were increasing revealed (1) some robust dierences in the dynamics between seasons that were not obvious in the time series data themselves and (2) that the series were almost all at their theoretical maximum entropy value when considered from the simple perspective of whether instantaneous change along the sequence was positive

Effects of punctuated heat stress on the grapevine powdery mildew pathogen, Erysiphe necator

Grapevine powdery mildew, caused by the ascomycete Erysiphe necator, is a major threat to grapes worldwide. Despite its global impact on grape production, E. necator is sensitive to adverse environmental conditions, such as excess heat, free water and UV radiation. Using detached leaf co-culture assays, 3-d-old single colonies of E. necator were exposed to 1, 2 or 3 consecutive d of punctuated heat stress. While there was a consistent decrease in colony growth after a single heating event, there were little to no significant effects from subsequent heating events. Similar effects were observed on the latent period of the pathogen, with a large initial effect from the first heat treatment and small marginal effects from subsequent heat treatments. Erysiphe necator colonies growing on live pot-grown plants were affected similarly by consecutive heat stress events. These data suggest that E. necator is more adaptable to environmental stress than previously recognized

The Use and Role of Predictive Systems in Disease Management

Disease predictive systems are intended to be management aids. With a few exceptions, these systems typically do not have direct sustained use by growers. Rather, their impact is mostly pedagogic and indirect, improving recommendations from farm advisers and shaping management concepts. The degree to which a system is consulted depends on the amount of perceived new, actionable information that is consistent with the objectives of the user. Often this involves avoiding risks associated with costly disease outbreaks. Adoption is sensitive to the correspondence between the information a system delivers and the information needed to manage a particular pathosystem at an acceptable financial risk; details of the approach used to predict disease risk are less important. The continuing challenge for researchers is to construct tools relevant to farmers and their advisers that improve upon their current management skill. This goal requires an appreciation of growers’ decision calculus in managing disease problems and, more broadly, their overall farm enterprise management.Keywords: plant pathogen, IPM adoption, diffusion theory, disease control, disease forecastin

Karpography: a generic concept of quality for chain analysis and knowledge transfer in supply chains

As with other areas of science, supply chain analysis suffers from the fact that practitioners of its different component disciplines often find it exchange results and methods of analysis. For fresh produce supply chains a key issue is how to unite the elegant mathematical work on the physiology of quality change with the more qualitative methods of social science that are applied to the analysis supply chain management. This paper explores the possibility of utilising approaches which are widely used in demography to unify concepts of quality modelling and supply chain efficiency in the fresh produce sector. A key feature of demographic (or karpographic) models is that they use the average properties of individuals to model the behaviour of cohorts (or batches) and thus have a direct means of including biological variance within their scope. We illustrate the potential of matrix projection models to provide a simple way to unite mathematical analyses of keeping quality and subjective and qualitative analyses of supply chain efficiency. Among other results, the paper demonstrates a rational basis for the assumption, which has been adopted in recent policy changes to the EU food and agriculture policy, that short (or local) supply chains are, ceterus paribus, superior to longer ones. The analytical approach suggested spans the gap between theoretical modelling and knowledge transfer in a single step and requires no more to allow parameterisation than the elicitation of subjective probability estimates from supply chain participants on the transition of produce from one quality class to another