No abstract

Potato virus Y (PVY) is one of the most important of the potato viruses, but little is known about the impact on yield of seedborne infection levels below 100%. Blending infected and healthy seed from different seed lots introduces the variable of performance differences between the seed lots, which may obscure the effect of virus alone. Seed lots containing various levels of seedborne PVY (0, 2, 10, 20, and 50% incidence of infected tubers) were created by combining in different proportions seed pieces from healthy and infected tubers from the same seed source. These seed lots were planted in replicated field plots at the University of Idaho Parma R & E Center in Parma, ID from 1995 to 1997. Regression analyses on data from the three consecutive seasons indicate that seedborne PVY has virtually the same negative impact on yield for all three cultivars.

Previous studies have shown that Potato virus Y (PVY) reduces yield in many cultivars. Typical foliar symptoms can include veinal necrosis, leaf drop, and a mosaic pattern sometimes accompanied by leaf roughness. Infection by PVY in Russet Burbank produces identifiable PVY symptoms, whereas cv. Russet Norkotah expresses mild, almost latent symptoms. Yield also is influenced by nitrogen fertilizer levels. This research was conducted to determine whether increased nitrogen mitigates yield reduction caused by PVY. Russet Norkotah, CO80011-5, and Russet Burbank were used in replicated plots of non-PVY-infected and PVY-infected plants at three nitrogen levels in 1995 and 1996. There was a significant yield reduction between PVY-negative and PVY-positive plots in all cultivars, at most nitrogen levels. PVY yield reduction was similar (approximately 38%) in the mild symptom expression clones of Russet Norkotah and CO80011-5, whereas the yield reduction in Russet Burbank, which exhibits typical symptom expression, was 63.5%. We conclude that increased nitrogen can influence total yield, but does not significantly mitigate the yield reduction due to PVY infection.

Invasive species policy is an economic issue. People affect the spread of invasive species, and these invaders affect people. This review discusses bioeconomic modeling using endogenous risk theory to capture the idea of jointly determined ecological and economic systems. This perspective adds precision to risk assessment and cost-benefit estimation. Bioeconomic modeling can help increase the chance of developing policies that promote better invasive species protection at lower cost. Several key points emerge. Differentiating between import- and export-related externalities determines the ability of agents to manage risk. A manager has four general economic strategies to mitigate invasive species risk and associated damages: prevention, eradication, control, and adaptation. When flexibility and timing play a critical role, a real options framework becomes the more appropriate analytical framework relative to traditional cost-benefit analysis. For many invasive species, valuation exercises will involve eliciting preferences to delay in the inevitable invasion and spread.

Purpose The purpose of this paper is to examine the relationship between employees’ perceptions of organizational support for employee health (OSEH) and employees’ turnover intention and job performance, with a focus on the possible mediating roles of affective commitment and wellness program participation in these relationships. Design/methodology/approach Data were collected from surveys of employees at a public university that provides employees with a variety of wellness program options. Conditional procedural analysis was conducted to test the model. Findings Results showed that employees’ perceptions of OSEH positively related to both turnover intention and job performance and that affective commitment fully mediated the relationships between OSEH perceptions and both dependent variables. Research limitations/implications Cross-sectional data were collected on OSEH, affective commitment, employees’ intent to remain in the organization and job performance. Future studies based on panel data would be helpful to establish the causal relationships in the model. Practical implications Our findings show that employees’ perceptions of OSEH are likely to affect behavioral outcomes through affective commitment, suggesting that managers should ensure that employees are aware of organizational support for health promotion. Our findings also suggest that organizations move beyond a focus on design of wellness programs to include an emphasis on the overall OSEH. Originality/value This research study is the first empirical examination on the two possible channels through which organizational health support may influence employees’ intent to remain and job performance – participation in wellness programs and affective organizational commitment. The results are of value to researchers, human resource management managers, employees and executives who are seeking to develop practices that promote employee health at the workplace.