PREDICTING POTENTIAL ASCOSPORE DOSE OF VENTURIA INAEQUALIS (CKE) WINT IN COMMERCIAL APPLE ORCHARDS OF NEW HAMPSHIRE (MODELING, EPIDEMIOLOGY, DISEASE MANAGEMENT)

A theoretical model (Prot. Ecol. 5:103-125) was the framework of a study of factors affecting the number of Venturia inaequalis ascospores per m(\u272) orchard floor per season (PAD) in New Hampshire apple orchards. PAD was calculated as the product of scab lesions per m(\u272) leaf tissue at leaf fall, pseudothecia per lesion, asci per pseudothecium, the proportion of the orchard floor covered by leaf litter at bud break, and ascospores per ascus. Disease incidence and the proportion of lesions that formed mature ascocarps were strongly correlated; lesion fertility was directly proportional to disease incidence at leaf fall. Most lesions from commercial orchards did not produce mature ascocarps. However, even when disease incidence was near zero, approximately 3% of the lesions formed mature ascocarps. Mechanisms were discussed by which sexual reproduction could occur when the probability of pairing of compatible mating types was remote. Infertile lesions were associated with aborted ascocarps as observed by Keitt and Palmiter (Amer. J. Bot. 25:338-345). The number of asci per ascocarp and the number of ascocarps per lesion did not differ on McIntosh, Cortland, or Delicious leaves. Leaves decayed primarily during winter and only slowly from bud break to petal fall. PAD varied from 13 to 44,544 ascospores/m(\u272)/season in orchards where 0.04% and 9.32% of the leaves were infected the previous autumn, respectively. A model proposed by Van der Plank was used to compute time differences ((DELTA)t) in the onset of scab epidemics based on differences in PAD. Spray programs for apply scab could be delayed by 2-22 days in commercial orchards depending on PAD and the value of Van der Plank\u27s infection rate (r)

Distributions d'auto-amorçage exactes ponctuelles des courbes ROC et des courbes de coûts

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Ascospore release by Venturia inaequalis during periods of extended daylight and low temperature at Nordic latitudes

Darkness suppresses ascospore release in Venturia inaequalis, but the impact of light levels during the extended twilight and dusk that typify Nordic spring conditions is poorly understood. Volumetric spore traps were operated at two different locations in Norway over several years. During the season of asocspore release (approximately 1 April to 30 June), on 25 occasions when rain started during night (after 23:00h and before 04:00h) and leaves remained wet until at least midnight the following day, the cumulative percentage of spores trapped at sunrise did not exceed 1%, irrespective of temperature. Three hours after sunrise, cumulative ascospore release reached 0.8%, 3.0%, and 8.1% at temperatures of 0 to 5°C, 5 to 10°C, and >10°C, respectively, and 50% release occurred at 11, 9, and 8h after sunrise. Additional field and laboratory studies indicated that the protracted dawn and dusk of Nordic latitudes, either alone or in combination with low temperatures, does not substantially alter previously reported patterns of ascospore releas

DMI Fungicides on Apples: Survival of the Apple Scab Pathogen in Sprayed Leaves, Late-Season Scab, and Sustainability of DMI Use in IPM Programs

NYS IPM Type: Project ReportDMI fungicides such as Rubigan and Nova represent a class of widely used and highly effective pest management tools in New York's apple IPM programs. Our recent research has indicated some potentially serious problems attending the continued use of DMI fungicides

An in vitro and in vivo evaluation of peroxyacetic acid as an alternative sanitizer for wine barrels

Peroxyacetic acid is a common sanitizer used in the food and wine industry, but its use as a sanitizer for wine barrels has not been reported. We are reporting the findings for in vitro studies using three different concentrations of peroxyacetic acid (0, 60, and 120 mg/L) as sanitization challenges against seven strains of wine spoilage yeast representing three different species: Dekkera /Brettanomyces bruxellensis (three strains), Saccharomyces cerevisiae (three strains) and Zygosaccharomyces bailii (one strain). In vitro sensitivity to peroxyacetic acid concentration varied within and between species. A post hoc study (in vivo ) using the highest concentration from the in vitro studies (120 mg/L) as well as 200 mg/L was performed to validate a sanitization method for wine barrels. Exposure of barrels to 200 mg/L of peroxyacetic acid for one week resulted in no detectable levels of wine spoilage microorganisms after treatment. These findings are crucial for establishing protocols to assure the maximum reduction of microbial contaminants

A Next-generation Marker Genotyping Platform (AmpSeq) in Heterozygous Crops: A Case Study for Marker-assisted Selection in Grapevine

Marker-assisted selection (MAS) is often employed in crop breeding programs to accelerate and enhance cultivar development, via selection during the juvenile phase and parental selection prior to crossing. Next-generation sequencing and its derivative technologies have been used for genome-wide molecular marker discovery. To bridge the gap between marker development and MAS implementation, this study developed a novel practical strategy with a semi-automated pipeline that incorporates traitassociated single nucleotide polymorphism marker discovery, low-cost genotyping through amplicon sequencing (AmpSeq) and decision making. The results document the development of a MAS package derived from genotyping-by-sequencing using three traits (flower sex, disease resistance and acylated anthocyanins) in grapevine breeding. The vast majority of sequence reads ( ⩾99%) were from the targeted regions. Across 380 individuals and up to 31 amplicons sequenced in each lane of MiSeq data, most amplicons (83 to 87%) had o10% missing data, and read depth had a median of 220–244 × . Several strengths of the AmpSeq platform that make this approach of broad interest in diverse crop species include accuracy, flexibility, speed, high-throughput, lowcost and easily automated analysis

The seeds of divergence: the economy of French North America, 1688 to 1760

Generally, Canada has been ignored in the literature on the colonial origins of divergence with most of the attention going to the United States. Late nineteenth century estimates of income per capita show that Canada was relatively poorer than the United States and that within Canada, the French and Catholic population of Quebec was considerably poorer. Was this gap long standing? Some evidence has been advanced for earlier periods, but it is quite limited and not well-suited for comparison with other societies. This thesis aims to contribute both to Canadian economic history and to comparative work on inequality across nations during the early modern period. With the use of novel prices and wages from Quebec—which was then the largest settlement in Canada and under French rule—a price index, a series of real wages and a measurement of Gross Domestic Product (GDP) are constructed. They are used to shed light both on the course of economic development until the French were defeated by the British in 1760 and on standards of living in that colony relative to the mother country, France, as well as the American colonies. The work is divided into three components. The first component relates to the construction of a price index. The absence of such an index has been a thorn in the side of Canadian historians as it has limited the ability of historians to obtain real values of wages, output and living standards. This index shows that prices did not follow any trend and remained at a stable level. However, there were episodes of wide swings—mostly due to wars and the monetary experiment of playing card money. The creation of this index lays the foundation of the next component. The second component constructs a standardized real wage series in the form of welfare ratios (a consumption basket divided by nominal wage rate multiplied by length of work year) to compare Canada with France, England and Colonial America. Two measures are derived. The first relies on a “bare bones” definition of consumption with a large share of land-intensive goods. This measure indicates that Canada was poorer than England and Colonial America and not appreciably richer than France. However, this measure overestimates the relative position of Canada to the Old World because of the strong presence of land-intensive goods. A second measure is created using a “respectable” definition of consumption in which the basket includes a larger share of manufactured goods and capital-intensive goods. This second basket better reflects differences in living standards since the abundance of land in Canada (and Colonial America) made it easy to achieve bare subsistence, but the scarcity of capital and skilled labor made the consumption of luxuries and manufactured goods (clothing, lighting, imported goods) highly expensive. With this measure, the advantage of New France over France evaporates and turns slightly negative. In comparison with Britain and Colonial America, the gap widens appreciably. This element is the most important for future research. By showing a reversal because of a shift to a different type of basket, it shows that Old World and New World comparisons are very sensitive to how we measure the cost of living. Furthermore, there are no sustained improvements in living standards over the period regardless of the measure used. Gaps in living standards observed later in the nineteenth century existed as far back as the seventeenth century. In a wider American perspective that includes the Spanish colonies, Canada fares better. The third component computes a new series for Gross Domestic Product (GDP). This is to avoid problems associated with using real wages in the form of welfare ratios which assume a constant labor supply. This assumption is hard to defend in the case of Colonial Canada as there were many signs of increasing industriousness during the eighteenth and nineteenth centuries. The GDP series suggest no long-run trend in living standards (from 1688 to circa 1765). The long peace era of 1713 to 1740 was marked by modest economic growth which offset a steady decline that had started in 1688, but by 1760 (as a result of constant warfare) living standards had sunk below their 1688 levels. These developments are accompanied by observations that suggest that other indicators of living standard declined. The flat-lining of incomes is accompanied by substantial increases in the amount of time worked, rising mortality and rising infant mortality. In addition, comparisons of incomes with the American colonies confirm the results obtained with wages— Canada was considerably poorer. At the end, a long conclusion is provides an exploratory discussion of why Canada would have diverged early on. In structural terms, it is argued that the French colony was plagued by the problem of a small population which prohibited the existence of scale effects. In combination with the fact that it was dispersed throughout the territory, the small population of New France limited the scope for specialization and economies of scale. However, this problem was in part created, and in part aggravated, by institutional factors like seigneurial tenure. The colonial origins of French America’s divergence from the rest of North America are thus partly institutional