Nursery and greenhouse products are economically important agricultural commodities for Oregon and Washington. Nursery crops including tree seedlings can be damaged or killed by soilborne plant pathogens, which can be challenging to manage because of their persistence in soil and limited options for control. Soil solarization is a pre-planting soil...
Phytophthora ramorum continues to cause extensive mortality of tanoaks in southwestern Oregon. Rain readily washes inoculum down through the canopy, causing new infections on the lower parts of the tree and neighboring host plants. Although this aspect of dispersal is well understood, the relative importance of infested soil and leaf...
Phytophthora pini Leonian, recently re-established from P. citricola
I, is a pathogen with a wide range of forest and nursery hosts. It causes foliar
infections in horticultural nurseries in Oregon, where recirculating irrigation
systems are common. Increased use of recirculating irrigation systems may
contribute to disease caused by waterborne plant...
Striga, a genus of obligate parasitic weeds in the family Orobanchaceae, has been
identified as the most important biological factor limiting agricultural productivity in sub-Saharan Africa. Germination of Striga seeds is triggered by strigolactone root exudates
from host plants. Strigolactones also induce hyphal branching in arbuscular mycorrhizal
(AM) fungi, which...
In horticultural nurseries for container-grown plants, production and sales have been threatened by the presence of a quarantined plant pathogen, Phytophthora ramorum (causal agent of sudden oak death). Infested nursery beds are an important source of P. ramorum, which can initiate disease through movement with surface water to infect roots...
The genus Phytophthora comprises numerous plant pathogens in both natural and managed ecosystems. For Phytophthora spp. that infect roots, dispersal occurs in soil water through a combination of advection and swimming of specialized motile propagules (zoospores). Specific biological and physico-chemical processes, however, remain poorly understood, due to difficulties in studying...
Weed management is one of the main challenges for organic agriculture. Soil solarization has been shown to be an effective mitigation strategy for weeds and soil borne plant pathogens but few studies have been conducted in cooler climates such as the Pacific Northwest.
Solarization could be an alternative to chemical controls for soil pathogens and weeds, and it may also influence plant growth factors. Biomass, shoot length, and AMF colonization were examined in red oak (Quercus rubra), Mazzard cherry (Prunus avium), and hawthorn (Crataegus monogyna) at J. Frank Schmidt & Son Co. nursery...
Infestations of container nursery beds by Phytophthora spp. can be persistent and costly. One method of disinfestation that does not require the use of chemicals is soil solarization, which captures energy from the sun to heat soil and thermally inactivate target pathogens. In laboratory temperature gradient experiments, I investigated the...
Interest in measuring soil quality continues to increase worldwide in view of demands on land productivity and the necessity to preserve soil resources, yet identification of suitable indicators for soil quality assessment is still evolving. This study adapted 10 biological, physical, and chemical indicators of soil quality identified by the...