Late blight disease caused by Phytophthora infestans continues to pose a great challenge for potato and tomato growers around the world. Despite the numerous efforts conducted to alleviate the losses caused by this disease, the pathogen's diversity has been a key factor in disease control failures. Continuous monitoring of pathogen traits such as fungicide sensitivity and host preference are essential for selecting the best disease mitigation method. The overall objective of this study was to understand the P. infestans population in the USA. More specifically, my research objectives were: i) To characterize the phenotypes of the most recent and most prevalent strains of P. infestans in the US; ii) To investigate a set of rare and diverse genotypes detected in the northeastern US in 2010 and 2011; iii) To study the phenotypic diversity (mating type, host preference, sensitivity to mefenoxam, the effect of temperature on release of zoospores and the effect of temperature on mycelial growth) of a diverse panel of P. infestans from the US, Mexico and the Netherlands and determine the genetic relatedness among them; iv) To conducted a genome-wide association study to identify genetic markers associated with important phenotypic traits; and v) To investigate the characteristics of mefenoxam acquired resistance. Differences in mating type, mefenoxam sensitivity, pathogenicity on potato and tomato, and zoospore release at different temperatures were identified between the recent genotypes of P. infestans in the US (US-8, US-22, US-23, and US-24). The genetic characteristics of the rare and diverse genotypes detected in the northeastern US were consistent with a recombinant population. The phenotypic analyses conducted on strains from the US, Mexico and the Netherlands, revealed a broad range of phenotypic responses. Eleven association hits for mating type in P. infestans where found with a P

In this personal history, one of the pioneers in population genetics recounts the evolution of his ideas about the effects of genetic variability on a population. Tracing the results of successive experiments over the years, it is, like the author's career, highly original.

In the last four decades of the twentieth century the use of sweetpotato was diversified beyond their classification as subsistence, food security, and famine-relief crop. In developing countries they serve both as human food and for feeding livestock. In Western countries they appeal to health conscious consumers because of their nutritional aspects. The sweetpotato is very high in nutritive value, and merits wider use on this account alone. The book has 2 parts. A general one giving up-to-date information on the history, botany, cultivars, genetic engineering, propagation, diseases and pests, nutritional data and marketing; and a second part presenting data on sweetpotato growing practices in different areas of the world. The information should be useful to researchers, practitioners and crop administrators in different countries.

The present guide is designed to assist professionals and technicians in charge of evaluation trials designed to screen selected potato genotypes for resistance to this disease. The evaluation of breeding families, which is carried out under greenhouse or field conditions, can use the same methodology. The guide can help to organize trials, improve data collection and analysis and introduces new criteria for resistance measurement based on epidemiological principles.