Leaf stripe resistance of spring barley cultivars

Results of six years of screening trials clearly indicate that effective resistance against barley leaf stripe is available, also in modern cultivars. Among the spring barley cultivars that are currently most widely grown in Denmark, Cabaret, Troon, Sebastian, Justina and Brazil appear most resistant, but only Brazil combines a favourable resistance performance (= low mean and standard deviation of environment-adjusted leaf stripe incidence) with a high number of observations (= years of testing). However, the cultivars appearing most resistant over the years are relatively old ones such as Vada, Alabama, Odin and particularly Scarlett, which has been resistant in all years in which it was tested. Amongst the new cultivars, Marigold, Native and SW Immer appear to have the most promising resistance properties so far. However, they have only been tested in two years of which only one had reasonably high infection levels. The results furthermore indicate huge year-to-year variation in infection levels, presumably due to variation in environmental conditions related to leaf stripe infection

Simulating properties of the likelihood ratio test for a unit root in an explosive second order autoregression

This paper provides a means of accurately simulating explosive autoregressive processes, and uses this method to analyse the distribution of the likelihood ratio test statistic for an explosive second order autoregressive process. Nielsen (2001) has shown that for the asymptotic distribution of the likelihood ratio unit root test statistic in a higher order autoregressive model, the assumption that the remaining roots are stationary is unnecessary, and as such the approximating asymptotic distribution for the test in the difference stationary region is valid in the explosive region also. However, simulations of statistics in the explosive region are beset by the magnitude of the numbers involved, which cause numerical inaccuracies, and this has previously constituted a bar on supporting asymptotic results by means of simulation, and analysing the finite sample properties of tests in the explosive region.

High damage potential of seed-borne spot blotch in organically grown spring barley in Denmark

Spot blotch of barley (Bipolaris sorokiniana, perfect state: Cochliobolus sativus) occurs wherever barley is grown but is normally not considered a major problem in Danish barley production. It is therefore not included in routine disease surveys or official variety testing in Denmark. However, recommended seed contamination thresholds are 30% for spring barley and 15% for winter barley. Several spring barley varieties were grown under organic (no seed dressing, mechanical weeding) and conventional (seed dressing with fungicides, herbicide application) production conditions at three sites in Denmark in 2003. The harvested seeds were analysed for contamination levels of seed-borne B. sorokiniana using a blotter method. The percentage of seeds contaminated with B. sorokiniana ranged from about 5 to 95 % and was highly depending on the site, production system and variety. Contamination levels of organically cultivated plots were about twice as high as those of plots receiving conventional treatments. The germinating ability of seeds was highly affected by the level of B. sorokiniana contamination and declined drastically at contamination levels above 60%. This effect appeared to differ among varieties. The 1000-grain weight was not affected by the level of spot blotch contamination of seeds. The results indicate that the importance of spot blotch may be underrated, especially in organic barley production and that the role of varietal resistance should be investigated. More results are expected from ongoing seed analyses

Farming in the "New Economy" : An Australian Perspective

Barriers to trade between countries have reduced through the general Agreement on Tariffs and Trade (GATT) and the World Trade Organisation (WTO). The nature of trade between businesses is also changing dramatically through developments in Information Technology but also due to adoption of quality assurance and new approaches to supply chain management. The impacts of this "New Economy" vary around the world. This paper considers the implications of these developments for Australian farmers. Whilst these changes can be regarded as generally advantageous to Australian farmers, they may be disadvantaged in some areas because of the relatively small size of the Australian farming sector, its geographical dispersion, the advent of a range of new technologies and the structure of agribusinesses. The potential changes to the nature of farming and farm management skills are discussed.Farm Management,

Identification of the age-period-cohort model and the extended chain ladder model

In this paper, we consider the identification problem arising in the age-period-cohort models, as well as in the extended chain ladder model. We propose a canonical parametrization based on the accelerations of the trends in the three factors. This parametrization is exactly identified. It eases interpretation, estimation and forecasting. The canonical parametrization is shown to apply for a class of index sets which have trapezoid shapes, including various Lexis diagrams and the insurance reserving triangles.

Self-Similarity and Lamperti Convergence for Families of Stochastic Processes

We define a new type of self-similarity for one-parameter families of stochastic processes, which applies to a number of important families of processes that are not self-similar in the conventional sense. This includes a new class of fractional Hougaard motions defined as moving averages of Hougaard L\'evy process, as well as some well-known families of Hougaard L\'evy processes such as the Poisson processes, Brownian motions with drift, and the inverse Gaussian processes. Such families have many properties in common with ordinary self-similar processes, including the form of their covariance functions, and the fact that they appear as limits in a Lamperti-type limit theorem for families of stochastic processes.Comment: 23 pages. IMADA preprint 2010-09-0

Resistens hos sorter af hvede og triticale mod stinkbrand og stængelbrand

Danish wheat and triticale varieties have been tested against resistance to common bunt (Tilletia tritici) and stripe smut (Urocystis occulta, only triticale) by artificial inoculation

Threshold levels for seed borne diseases in organic cereals

Seed borne diseases can cause serious problems in organic seed production where there is no control methods implemented in practice. Current practice in organic agriculture is to analyse the seed and to discard the seed lot if the infection by diseases exceeds the threshold levels. There is no tolerance list specific for organic agriculture. In Denmark we use the same threshold values as recommended in conventional agriculture for seed treatment

Nyt bio-middel mod bygbladplet

Cedomon, et nyt biologisk bejdsemiddel mod bygbladplet i byg. Godkendt 2004 i Danmark med dosering 7,5 ml pr. kg byg. Produktet endnu ikke (2006) markedsført

The Effects of Delay and Probabilistic Discounting on Green Consumerism

People have a tendency to discount outcomes that are delayed or probabilistic. In other words, people will sacrifice larger benefits for smaller benefits that are immediate or certain. For many environmentally-friendly (“green”) products, the financial benefits are both delayed and probabilistic. The current study examined how delay and probability, as well as frame and magnitude, influenced consumers’ decisions when comparing a conventional and green product. Participants were recruited from Amazon’s Mechanical Turk and completed one of two experiments. In each experiment participants chose between a conventional product (low initial cost, high operating cost) and green product (high initial cost, low operating cost). Magnitude was manipulated by randomly assigning participants to a light bulb (low magnitude) or water heater (high magnitude) condition. Within each magnitude condition, promotional messages highlighted the increased operating cost of the conventional product (loss frame) or decreased operating cost of the green product (gain frame). Probability was manipulated in experiment one and inferred by the participant in Experiment 2. Results supported the recent finding that delay and probability interact. When probabilities of savings were high, participants were more likely to select the green product. This finding occurred whether probabilities were manipulated (Experiment 1) or inferred (Experiment 2). Framing and magnitude effects were inconsistent across experiments. Marketers promoting green products should take steps to reduce perceived risk associated with green products