Entomopathogenic fungi are cosmopolitan microbial pathogens that cause fungous diseases in a wide range of insects via spore infection. Due to their natural enemy status, they have tremendous potential for use as microbial control agents against insect pests, especially subterranean pests for which few management options are available. The clover...
We evaluated genes previously identified from a large scale functional genomics screen for their potential value to help enhance carbon sequestration in planted trees. We used poplar as a model tree species because of its abundant genetic variation, ease of gene transfer, and availability of large databases for genomic, anatomical,...
Orchardgrass (Dactylis glomerata L.) is an important seed crop, but unlike other cool-season perennial grass seed crops such as perennial ryegrass (Lolium perenne L.) and tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.], seed yields have not increased over time so there is considerable room for improvement. Research suggests that plant growth...
The climate of the Pacific Northwest is in flux, and existing forest ecosystems are stressed and poised to shift in fundamental ways, with or without human intervention. This dissertation probes the nature of forest responses to environmental change through investigations of morphology and genetics of three species of alder co-occurring...
Drosophila suzukii (Diptera: Drosophilidae), is a serious pest in soft and stone fruit industries worldwide. The unique serrated ovipositor of female Drosophila suzukii allowed the species to reproduce in intact, ripening fruit before the harvest. Current control methods rely heavily on insecticide application, only becoming less profitable due to the...
The goal of this dissertation is to examine the effectiveness of high intensity-short duration goat browsing for the control of Himalayan blackberry (Rubus armeniacus) and English ivy (Hedera helix), two widespread noxious weeds in the Pacific Northwest.
The effects of goat browsing on Himalayan blackberry vigor, as quantified by densities...
Douglas-fir (Psudotsuga menziesii (Mirb.) Franco) seedlings were outplanted on eight dates (every three weeks from mid-August 2005 through mid-January 2006). On each plant date, seedlings from a conventional dormancy (CONV) induction treatment, including moisture and nutrient stress, and a shortened daylength (SD) treatment were outplanted on three western Oregon sites...
Two experiments were conducted to evaluate the influence of a yeast-derived cell wall preparation (YCW) on forage intake and digestibility, ruminal fermentation characteristics, serum prolactin and prolactin stores, and milk production in beef cattle consuming high-alkaloid tall fescue straw. In Exp. 1, 16 Angus x Hereford ruminally cannulated steers (200...
Quantitative resistance (QR) to disease is usually more durable than qualitative resistance, but its genetic basis is not well understood. We used the barley/barley stripe rust pathosystem as a model for the characterization of the QR phenotype and associated genomic regions. As an intermediate step in the preparation of near-isogenic...
One of the most economically important genes in squash (Cucurbita spp.) is the B gene which conditions precocious depletion of chlorophyll in preanthesis fruit. The B genes are found naturally occurring in at least three of the five domesticated species of Cucurbita, including C. pepo, C. maxima and, most recently...
Grasslands in the Pacific Northwest are characterized by seasonally wet, acidic soils that mainly support cool season grasses and a limited number of legume species. A major limitation to efficient animal production in grass-dominant pastures is the decline in the herbage growth rate and nutritional quality of forage from late...
Xanthomonas hortorum pv. carotae (Xhc) is an epiphytic, plant pathogenic bacterium that causes the disease bacterial blight of carrot (Daucus carota subsp. sativus). Infection with Xhc can result in blighting of leaves and umbels and reduce quality and yield of carrot seed crops. Carrot production in the United States approaches...
This study investigated the effects of diversification strategy through the inclusion of forb and legume based pastures in the feedbase of dairy cows on annual forage production, botanical composition, spring milk yield, N partitioning and methane emissions from dairy cows in Western Oregon. Using a randomized complete block design, 3...
This thesis consists of three manuscripts addressing separate components of barley breeding, plus an introduction and a conclusion summarizing the status of barley in the Pacific Northwest, plus the implications of the research presented in this thesis. In the first manuscript, a package written for the statistical software "R" that...
The following experiment presented herein compared growth, physiological, and reproductive responses of beef heifers with (MI) or without (CON) access to a creep-feeder, as a manner to stimulate metabolic imprinting while nursing their dams. On d 0 of the experiment, 60 Angus × Hereford heifers were ranked by initial BW...
Controlling competing vegetation with the application of herbicides and increased seedling size at planting has been shown to increase seedling survival and growth. These two important reforestation tools have often been studied independently of each other, limiting comparisons that can be made between them. This study utilized a factorial treatment...
Two studies were conducted to evaluate the influence of supplement composition on intake and digestibility of a low-quality (< 6% CP), cool-season forage, as well as cow performance. Treatments included a non-supplemented control (CON), corn (approximately 8% CP), corn and urea (LU = corn + 0.09 mg/kg BW urea, approximately...
In arid and semi-arid deserts, soils are commonly covered with biological soil crusts. The
study of arid biocrusts and their ecological function has become increasingly common in
the literature over the last several decades. Interestingly, no mention is made of
biological soil crusts in forested ecosystems, raising the question as...
Limnanthes floccosa ssp. floccosa and L. floccosa ssp. grandiflora are two of five subspecies of Limnanthes floccosa endemic to vernal pools in southern Oregon and northern California. Three seasons of monitoring natural populations have quantified that L. floccosa ssp. grandiflora is always found growing sympatrically with L. floccosa ssp. floccosa...
Concern over the increasing proportion of juvenile wood grown in second growth plantations has led to a large amount of research on the effects of common silvicultural practices on wood quality. Lacking is research on the effect of timing and
duration of vegetation control on wood quality near the pith...
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,...
Native populations of forest trees are specifically adapted to the climates they inhabit. The farther trees are moved from their local climates (i.e., as the climatic transfer distance increases), the more growth and survival tend to decrease. The transfer limit is the climatic transfer distance beyond which plantation performance is...
Douglas-fir (Pseudotsuga menziesii) is a widely distributed, ecologically important, and commercially valuable tree species in North America. However, climate change is expected to adversely impact Douglas-fir trees, and assisted migration may become necessary to lessen the effects of climate change. Because drought stress is one of the projected effects of...
Understanding complex traits is a fundamental challenge in plant genetics and a prerequisite for molecular breeding. Tools for trait dissection are markers, maps, and quantitative trait locus (QTL) analysis. Marker-assisted selection (MAS) is an application that integrates these tools. In this thesis research, a new sequence-based marker was evaluated, maps...
Estimates of nitrogen (N) available from long-term application of organic
amendments are required to balance N inputs with crop N requirements. Two studies
were conducted to (1) determine N mineralized from organic amendments (manures
and composts) during year 2 after application, and (2) compare plant-available N
(PAN) determined via in...
The purpose of this research was to develop tools and germplasm for the production of tomatoes (Solanum lycopersicum L.) with high fruit phenolics without the use of genetic engineering. A candidate gene analysis was undertaken to identify genes regulating anthocyanin biosynthesis in tomato fruit (Aft, Abg, atv, and Purple Smudge)....
Phytophthora ramorum is the causal agent of Sudden Oak Death (SOD), which is an economically and environmentally important disease causing up to 80% mortality of tanoaks in Pacific Northwest coastal forests (LeBoldus et al., 2022). There are currently four clonal lineages in the United States and Europe, named North America...
Gaseous transport through soil in the presence of soil
microorganisms has been investigated. More recently, modeling of
gaseous transport in the unsaturated zone has been investigated.
However, the problem of mathematical model of oxygen and carbon
dioxide transport through soil, as affected by the climatic
conditions, the transport of soil...
Meadowfoam (Limnanthes alba) is an oilseed crop with unique chemical characteristics. The ability to identify physiological maturity (PM) and harvest maturity HM of the crop would permit timely harvest of high quality seeds. However, changes of oil contents, fatty acid profile and glucosinolate contents, as well as seed quality during...
Meadowfoam (Limnanthes alba Hartw. ex Benth) seed meal (MSM), a by-product of meadowfoam oil extraction, has a plant defensive compound known as glucosinolate glucolimnanthin (GLN). Myrosinase enzymes present in soil microbes and meadowfoam seeds can convert GLN to glucosinolate breakdown products (GBPs), which demonstrate herbicidal activity and have the potential...
Timber-concrete composite (TCC) solutions originated in the early twentieth century. There has been a renewed interest in TCC solutions in modern mass timber buildings, especially for floor systems. However due to lack of data, design standards, and code acceptance, TCC solutions require that new mass timber solutions be tested, and...
Halyomorpha halys Stål, brown marmorated stink bug or BMSB, is now present in 43 US states. A native of eastern Asia, this pest can feed on ~200 different plant species damaging bark, leaves, buds, stems, and fruits. Many of these plant species include wild plants, ornamentals, and agricultural crops. BMSB...
Intimate associations with reactive metal species permanently protect soil organic matter (SOM) from microbial access and oxidation, contributing to the build-up of organic carbon (C) stocks in soils. It is increasingly recognized, however, that such associations can be reversible and that reactive metal species might even facilitate the oxidation of...