The European hazelnut (Corylus avellana L.) is a tree nut crop that is important in Oregon, which produces 99% of the United States’ hazelnuts but only 5% of the world’s supply. In order to maintain this market share, farmers in Oregon need cultivars that produce high quality nuts, mature early,...
On a global scale, potato (Solanum tuberosum L.) plays an important role in tackling the threat of food insecurity due to its high yield and broad global acceptance. However, pathogens threaten potato production, causing direct yield loss and rendering potatoes tubers unmarketable. Breeding new cultivars that carry multiple resistances is...
Bacterial blight (Xanthomonas arboricola pv. corylina) (Xac) of hazelnut (Corylus avellana L.) was described first in Oregon in 1915 and is now recognized as a damaging disease of young hazelnut trees worldwide. Stressed hazelnut trees in conditions such as planting on marginal sites, and trees between 1 and 4-years-old are...
Hibiscus and lilacs (Syringa spp.) are economically important nursery crops in the US that accounted for 4.5 million units ($30 million) and 2 million units ($20 million), respectively (USDA, 2016). To maintain and expand the market share of ornamental plants such as lilacs and Hibiscus, novel performance, floral ornamental value,...
Phytophthora root rot decreases availability and quality of rhododendrons produced in the USA. Symptoms of Phytophthora root rot include root necrosis, leaf chlorosis, stunting, and permanent wilt. The purpose of this thesis was to better understand the impact of root damage, soil moisture, nitrogen fertilizer application, and pathogen species on...
Hybridization, polyploidy, and apomixis have made phylogenetic estimation in Rubus challenging. I used target capture to sequence approximately 1000 low copy nuclear loci and the chloroplast genome for 94 accessions representing the genus Rubus and distributed worldwide. Species phylogenies were estimated using two coalescent based methods, ASTRAL-II and SVDQuartets, and...
The cultivated potato (Solanum tuberosum L.) is one of the world’s most important staple crops, ranked fourth after maize, rice, and wheat. While the potato’s success is due largely to its high yield, it also benefits from its broad global acceptance, and its ability to be used by the consumer...
Grape powdery mildew (GPM, causal agent Erysiphe necator) is the most economically important disease of grapevine in the Western U.S. Low levels of GPM infection on clusters (1-5%) can negatively affect wine sensory quality, so intensive fungicide programs are common. This may lead to problems like excessive fungicide use and...
Lilacs are a group of ornamental trees and shrubs in the Oleaceae family consisting of 22 to 30 species. There are six series within genus Syringa: Pubescentes, Villosae, Ligustrae, Ligustrina, Pinnatifoliae, and Syringa. Fertility and cross-compatibility among cultivars, species, and series have yet to be formally investigated. Over three years,...
The water status of grape vine throughout the growing season is a primary determinant of vine vigor and berry composition. The concentrations of volatile compounds and precursors in grape berries are highly influenced by viticultural practices. Imposing a water deficit on the vine during berry development is an important vineyard...