The extent of the competitive effect of wild oats on winter wheat
yield was estimated in field studies on three commercial wheat farms in
the Willamette Valley. The morphological development of the wild oat
plants was also documented.
Wild oats were removed from stands of wheat in six different treatments;...
Race identification of stripe rust (Puccinia striiformis West. )
is influenced by environment, pathogen variability and host age.
Isolates of stripe rust were collected in the Pacific Northwest and
characterized on two sets of differential varieties; the "Oregon" and
the United States. Six of the seven isolates tested on the...
In vitro tests showed mycelial growth of Pyrenochaeta
terrestris was inhibited by root and bulb extracts from the pink root
resistant onion cultivar Nebuka, but not by extracts from the susceptible
Southport White Globe. The active principle was shown to be
fungistatic rather than fungicidal. It is present in both...
Trifluralin (a, a, a - trifluoro -2, 6 -dinitro-N, N-dipropyl-ptoluidine)
is effective in controlling downy brome (Bromus tectorum
L.) and wild oat (Avena fatua L.) but does not severely affect the
growth of wheat (Triticum aestivum L.). Studies were conducted
using germination chamber and greenhouse facilities to investigate
possible factors...
Root rot of ponderosa pine caused by Armillaria mellea was
studied in a pine forest that had been under management for 30 years
in Klickitat County, Washington. Information sources included
disease survey, detailed observation and description of specific
disease situations, and examination of roots in situ and removed.
Roughly circular...
In 1967, Lophodermella morbida Staley and Bynum, a recently described
hypodermataceous needle-cast fungus, became destructively
epidemic in a knobcone pine (Pinus attenuata Lemm.) plantation in
Del Norte County, California, and in several ponderosa pine (P.
ponderosa Laws.) plantations in western and southwestern Oregon.
This thesis presents information on this currently...
Self-interactions (effects of reinoculation with the same nematode)
in Meloidogyne hapla and Heterodera schachtii on Beta vulpris at
different levels of inocula with various population combinations were
studied. In M. hapla, the only significant increase of galls was
noted in treatments when 250+250 larvae were inoculated at 10-day
intervals. Longevity...
Studies were conducted on the mechanisms contributing to
resistance in broccoli, Brassica oleracea italica, to the garden
symphylan, Scutigerella immaculata (Newport). Differences in
resistance to symphylan injury were shown between five selected
broccoli cultivars. The hybrid cultivars, Crusader, Green Duke
and Bravo, showed a higher level of resistance to symphylans...
The seasonal development and habits of Labops hesperius Uhler
were studied in rangeland seeded to intermediate wheatgrass (Agropyron
intermediurn (Host) Beauv. ) in Baker County, Oregon, The
first nymphs appeared on March 22, and required about one week to
complete each of the five nymphal stadia. Most small nymphs stayed...
Footrot of wheat (Cercosporella herpotrichoides Fron) is a
major disease of winter wheat in certain areas of the world having a
cool, damp winter and early spring climate. In Oregon, it is an
economic problem in the higher rainfall wheat-growing areas in the
eastern portion of the state. This study...