Abundant conidial production occurs from colonized straws and
plants infected with Cercosporella herpotrichoides Fron during the
cool moist months of the growing season. Experiments were
designed to study the survival, inoculum potential and competitive
saprophytic ability of conidia in soil.
Laboratory results indicated that cool moist soil favors the
saprophytic...
Sunflower (Helianthus annuus L., cv. NK894) seedlings, grown hydroponically, were exposed to ozone concentrations of 0.0, 0.1, 0.2, and 0.3 ppm at 60% RH, or 0.0
and 0.3 ppm at 30% and 90% RH, for 6 h/d, for four consecutive days, at ages 15 to 18 days from seeding. Plant...
This dissertation describes the epiphyte communities on tall shrubs in forests of
western Oregon, with a focus on potential effects of management practices on these
communities. Shrubs and other hardwoods have recently gained recognition as
hotspots of diversity for epiphytes in young conifer forests of the region. Yet little is...
The sagebrush steppe ecosystem of the northern Great Basin is severely degraded and continues to decline due in large part to the invasive, non-native annual grasses Bromus tectorum L. (cheatgrass) and Taeniatherum caput-medusae (L.) Nevski (medusahead). Restoration of invasive-dominated areas is difficult, but can be enhanced by adding a carbon...
Phyllopane microorganisms on the leaf surfaces of bean
(Phaseolus vulgaris L. ), hop (Humulus lupulus L. 'Fuggle-H'),
mint (Mentha piperita L. 'Mitcham') and tomato (Lycopersicon
esculentum Mill. ) has been observed by cultural methods. A leaf
impression method was used to examine both actively growing and
inactive propagules present on...
Developmental changes in the storage organ of Brassica
campestris L. were followed from the organization of the embryonic
radicle and hypocotyl to the mature storage organ. Three independent
primary meristems gave rise to the cortex, the stele, and the
root cap-epidermis. The primary development is typical of the
Cruciferae. Cambial...
Comparative morphological and anatomical studies of the dispersal mechanisms
characterizing the wheat complex (Triticum L. and Aegilops L.) have documented
patterns of adaptive radiation which may have significance for evolutionary
relationships. These patterns, which form an array of diverse types of diaspores
among the diploid taxa, appear conceptually to have...