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...
Disease control of soilborne pathogens by biological control agents
(BCAs) is often inconsistent under field conditions. This inconsistency
may be partly influenced by pathogen diversity if there is a differential
response among pathogen species and isolates to selected BCAs. The
responses of 148 Pythium isolates obtained from soil at three...
Phytophthora cinnamomi is a soilborne pathogen that causes root rot disease of highbush blueberry (Vaccinium corymbosum L.). When new installations of susceptible blueberry cultivars are infected with P. cinnamomi, plants often fail to grow significant new tissue, greatly reducing yields over the life of the planting. Chemical fungicides are available...
The Pacific Northwest produces over 95% of the nation’s processed red raspberries, valued at over $65 million. Two of the major soilborne pathogens effecting the production of raspberry in this region are the oomycete Phytophthora rubi, which causes root rot in red raspberry plants, and the plant-parasitic nematode Pratylenchus penetrans,...
Winter squash (Cucurbita maxima) grown in Oregon’s Willamette Valley for edible seed, frozen foods, and fresh markets is susceptible to an undiagnosed soilborne disease. Diseased squash fields exhibit symptoms of stunting, root and crown rot, vascular discoloration, and late-season wilt, which in extreme cases can lead to total crop failure....
Mefenoxam and fosetyl-Al are common fungicides used to supplement
disease control of Pythium damping-off and root rot in forest nurseries
of the western United States. However, it is unknown whether fungicide-resistant Pythium isolates are present or whether new fungicide
and biological treatments might also provide supplemental disease
control. Isolates of...
Pythium species are common soilborne oomycetes that occur in forest nursery soils throughout the United States. Numerous species have been described from nursery soils. However, with the exception of P. aphanidermatum, P irregulare, P. sylvaticum, and P ultimum, little is known about the potential for other Pythium species found in...
Meadowfoam (Limnanthes alba L.) is a herbaceous winter spring annual grown as a commercial oilseed crop. The meal remaining after oil extraction from the seed contains up to 4% of the glucosinolate glucolimnanthin. Degradation of glucolimnanthin yields toxic breakdown products, and therefore the meal may have potential in the management...
Phytophthora cinnamomi Rands is a ubiquitous soilborne pathogen associated with root rot in many woody perennial plant species, including highbush blueberry (Vaccinium corymbosum). To identify genotypes with resistance to the pathogen, cultivars and advanced selections of highbush blueberry were grown in a greenhouse and either inoculated or not with propagules...