Ecology and Management of Stemphylium Leaf Spot of Spinach

Stemphylium leaf spot of spinach has re-emerged as a disease of economic concern for fresh market, processing, and seed production. The two main causal agents, Stemphylium beticola and S. vesicarium, are seedborne and seed transmitted. The overall objective of this study was to elucidate the biology and epidemiology of these pathogens, and to refine management options for the disease by: i) identifying Stemphylium species and development of their teleomorphs associated with Stemphylium leaf spot in spinach seed crops, and species colonizing seed grown in key countries of seed production; ii) screening spinach cultivars for resistance to S. vesicarium; iii) determining the prevalence of resistance to the fungicides azoxystrobin and pyraclostrobin that have been used widely to control this disease; iv) evaluating genetic differences of pathogenic vs. non-pathogenic seedborne isolates of S. vesicarium; and v) sequencing the genome of S. beticola isolates to complement genomes available for S. vesicarium. Isolates of S. beticola, S. vesicarium, and S. drummondii were pathogenic to spinach, but eight other Stemphylium species associated with spinach were not. Cultivars with resistance to S. vesicarium were identified for fresh market and processing spinach production. In vitro and in vivo assays confirmed resistance to azoxystrobin and pyraclostrobin for all spinach leaf and seed isolates of S. vesicarium tested, but not isolates of S. beticola. Resistant isolates all had the G143A mutation in the cytochrome b gene that confers this resistance. The proportion of seedborne S. vesicarium isolates pathogenic to spinach varied among seed lots, and was negatively correlated with genetic diversity of the isolates. Seed populations of S. vesicarium were structured genetically based on pathogenicity to spinach, not by seed lot or country of seed production. Genotypes of pathogenic S. vesicarium isolates from leaf spots were detected on seed lots used to plant the crops, and seed populations were more diverse genetically than foliar populations. The sequenced genomes of two S. beticola isolates from spinach will facilitate genetic comparison of species that cause Stemphylium leaf spot, and development of molecular detection tools. This research provides new insights into Stemphylium leaf spot of spinach with implications for enhanced management of this disease

Characterisation of damage mechanisms in oxide ceramics indented at dynamic and quasi-static strain rates

Ceramic materials are known to display rate dependent behaviour under impact. Tests to establish the strain-rate dependent variations in damage mechanisms have been carried out on debased alumina, an alumina-zirconia composite, and 3Y-TZP. Materials were indented dynamically and quasi-statically using identical sharp hardened steel projectiles while recording the load profile. Characteristics typical of both sharp and blunt indentation types were observed using scanning electron microscopy and piezospectroscopic mapping. At dynamic strain rates both the depth of the indentation and the residual stress in the material were lower than for quasi-static tests. This was attributed to temperature-induced softening of the projectile. Unusual behaviour was observed in the 3Y-TZP samples due to the reversible transformation from tetragonal to monoclinic crystal structures during mechanical loading. These effects and the observed superior mechanical strength against impact suggest that zirconia or zirconia-composite materials may have advantages over debased alumina for application as ceramic armour materials

A healthy indulgence? Wine consumers and the health benefits of wine

Heart disease is the leading cause of death in the US. Moderate red wine consumption has been linked to a reduction in the risk of death by heart disease and heart attack by 30–50%. With about 600,000 people dying from heart disease in the US each year, red wine has become increasingly popular among health conscious consumers. Wine is often touted for its potential health benefits, but to what extent is “health” a factor when consumers make their consumption decisions for alcoholic beverages? This study aims to further understand how consumers make their beverage choices and to understand the role wine health benefit knowledge plays in the willingness of consumers to purchase wine. The results suggest that consumers value the relationship between food/beverage intake and their health status. Consumers with few health issues were the ones more likely to indicate that they consume wine for health reasons, suggesting a potential market among consumers with known health issues. In addition, consumers who attributed the most health benefits to wine were the ones most likely to drink more wine and pay more for wine if it were health enhanced