Rust-proofing wheat for a changing climate

This paper offers projections of potential effects of climate change on rusts of wheat and how we should factor in a changing climate when planning for the future management of these diseases. Even though the rusts of wheat have been extensively studied internationally, there is a paucity of information on the likely effects of a changing climate on the rusts and their influence on wheat production. Due to the lack of published empirical research we relied on the few published studies of other plant diseases, our own unpublished work and relevant information from the vast literature on rusts of wheat to prepare this overview. Three broad areas of potential risks from a changing climate were described: increased loss from wheat rusts, new rust pathotypes evolving faster and the reduced effectiveness of rust resistances. Increased biomass of wheat crops grown in the presence of elevated CO₂ concentrations and higher temperatures will increase the leaf area available for attack by the pathogen leading to increased inoculum production. If changed weather conditions were to accelerate the life cycle of a pathogen, the increased inoculum can lead to severe rust epidemics in many environments. Likewise should the effects of climate change result in more conducive conditions for rust development there will also be a corresponding increase in the rate of evolution of new pathotypes which could increase the rate of appearance of new virulences. The effectiveness of some rust resistance genes is influenced by temperature and crop development stage. Climate change may directly or indirectly influence the effectiveness of some resistance genes but this can not be ascertained due to a complete lack of knowledge. Since disease resistance breeding is a long term strategy it is important to determine if any of the important genes may become less effective due to climate change. Studies must be made to acquire new information on the rust disease triangle to increase the adaptive capacity of wheat under climate change. Leadership within the Borlaug Global Rust Initiative (BGRI) is needed to broker research on rust evolution and the durability of resistance under climate change.     

Height,competition and yield potential in winter wheat

Summary A monogenic dominant male sterility is used for hybrid production in autumn and winter cauliflower. The ratio of male sterile plants in the backcross progenies of autumn cauliflower was 1:1 over five years (1987–1991). However, a significant deficit of male sterile plants was observed in the winter type over the same period.The influence of the temperature on the male sterile phenotype was studied within backcross progenies planted inside polythene tunnels. Six classes of phenotype were defined during the flowering period (from May to November). At low temperature, some male sterile plants developed partial to complete male fertility, whereas at high temperature, male fertile plants became male sterile.Segregation among the progenies of self-pollinated unstable male sterile plants did not deviate from the expected 3:1 ratio. Plants homozygous for the male sterility allele have been revealed by test crosses with a male fertile plant.For use in seed production, stable male sterile plants are vegetatively maintained; however, crossing lines isogenic except at the MS locus would allow male sterile plants to be raised from seed.     

Comparison of core needle biopsy and fine-needle aspiration of enlarged peripheral lymph nodes for antemortem diagnosis of enzootic bovine lymphosarcoma in cattle

OBJECTIVE: To determine whether antemortem core needle biopsy and fine-needle aspiration of enlarged peripheral lymph nodes could be used to distinguish between inflammation and lymphosarcoma in cattle. DESIGN: Prospective study. ANIMALS: 25 cattle with enlarged peripheral lymph nodes. PROCEDURES: Antemortem biopsies of the selected lymph nodes were performed with an 18-gauge, 12-cm core needle biopsy instrument. Fine-needle aspirates were performed with a 20-gauge, 4-cm needle. Specimens were analyzed by pathologists who were unaware of clinical findings and final necropsy findings, and specimens were categorized as reactive, neoplastic, or nondiagnostic for comparison with necropsy results. RESULTS: Sensitivity and specificity of core needle biopsy ranged from 38% to 67% and from 80% to 25%, respectively. Sensitivity of fine-needle aspiration ranged from 41% to 53%, and specificity was 100%. Predictive values for positive test results ranged from 77% to 89% for core needle biopsy and were 100% for fine-needle aspiration. Predictive values for negative test results were low for both core needle biopsy and fine-needle aspiration. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that core needle biopsy and fine-needle aspiration can aid in the antemortem diagnosis of bovine enzootic lymphosarcoma. Results of fine-needle aspiration of enlarged peripheral lymph nodes were more specific and more predictive for a positive test result than were results of core needle biopsy.     

Amphibian orientation: an unexpected observation

The study of homing movements of displaced newts (Taricha rivularis) revealed unexpected features of the migratory behavior of amphibians. Newts leaving the breeding stream in the spring move not directly uphill but at an angle carrying them upstream. When they emerge after summer estivation this tendency is not evident in captures made during the autumn and winter. During the latter period, however, newly metamorphosed frogs (Rana boylii) show the same pronounced upstream migration that characterizes T. rivularis in the spring.     

Grand banks and j-anomaly ridge: a geological comparison

Geological and geophysical evidence supports the hypothesis that the J-anomaly ridge was a part of the Grand Banks in (late) Early Cretaceous time.     

Acid precipitation in the Western United States

Precipitation chemistry data from a rural area at an elevation of 2900 meters near the Continental Divide in Colorado show unexpectedly low pH values for bulk precipitation. A significant downward trend in pH over the last 3 years is associated with increasing amounts of nitric acid in precipitation.