A disease of sweet cherry (Prunus avium L.) known as "cherry
rosette" has threatened production of cherries in Oregon. In 1961
this disease was observed in widely separated orchards. Rosette
occurred in isolated trees or in spreading patterns, often from
identified single trees or from one section of an orchard....
Verticillium wilt of hops in Oregon, caused by Verticillium
dahliae Kleb., was first reported in 1956. Later, V. albo-atrum
Reinke & Berth. was also isolated from infected hop plants, and thus
both species of the fungus were shown to be the causal agents of the
disease in Oregon.
The purpose...
Verticillium dahliae Kleb. causes a wilt disease of peppermint.
Attempts to control the disease by soil fumigation, crop rotation,
flaming of stubble, and deep plowing have met with only limited success.
Development of resistant varieties through conventional breeding
procedures is difficult because commercial peppermint is male-sterile.
Several strains of commercial...
The fungus Phoma menthae Strasser causes black lesions and
cankers on stems and rhizomes of Mentha piperita L. The purpose
of this thesis was to: 1) study the production of polygalacturonase
(PG) and macerating enzymes (ME) by P. menthae in vivo and in
vitro, 2) study the effects of phenolic...
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...