Treesearch

The exclusion of anthropogenic fire is a primary factor responsible for the ‘mesophication’ of eastern oak (Quercus) forests and resultant oak regeneration problems. Consequently, the reintroduction of fire is increasingly used to promote the establishment and growth of oak and hickory (Carya) and control competition from shade-tolerant species (e.g., red maple (Acer rubrum)) in the forest understory. In this study, we examined the effects of fire frequency on the abundance of prominent species in the woody regeneration layer in oak-dominated forests of eastern Kentucky. Treatments...

Phytophthora lateralis causes root rot of Port-Orford cedar (Chamaecyparis lawsoniana; POC) in native forests of northwest California and southwest Oregon and in landscape plantings of horticultural Chamaecyparis cultivars in the western US and Europe. In spring 2015, following observations of mortality amongst plant groups in two horticultural nurseries in Oregon, P. lateralis was isolated from the roots of two additional conifer species: Microbiota decussata and Juniperus communis. Species identification was confirmed by sequencing the ITS region using ITS4 and ITS6 primers. To substantia...

Infected nursery plants play an important role in the spread of Phytophthora ramorum , the causal agent of sudden oak death and ramorum blight. In order to minimize the risk for disease transmission to new areas, nurseries are inspected regularly for P. ramorum , and federal regulations require the eradication of infested plants and the disinfestation of nursery soil and equipment. The National Ornamentals Research Site at Dominican University of California (NORS-DUC) is a federally funded research nursery devoted to testing and developing environmental friendly management options for...

The National Ornamentals Research Site at Dominican University of California (NORS-DUC) was founded in the year 2009 by a Farm Bill grant to study Phytophthora ramorum in a sophisticated research nursery that reflects an authentic commercial nursery setting (www.dominican.edu/norsduc). NORS-DUC goals are to develop practical solutions for containment, remediation, and eradication of quarantine pathogens in nurseries and to reduce the risk of long-range spread of pests through infested nursery stock shipments. Research at NORS-DUC is conducted by a team of permanent staff as well as by P....

Soil solarization has been shown to be an effective tool to manage Phytophthora spp. within surface soils, but estimating the minimum time required to complete local eradication under variable weather conditions remains unknown. A mathematical model could help predict the effectiveness of solarization at different sites and soil depths. Prior research on solarization efficacy has focused on the minimum temperature and exposure time required to kill pathogens, and most mathematical models of the effects are based on cumulative temperature over time. However, two additional factors, soil...

CALinvasives is a web-based relational database and content management system (CMS) cataloging the statewide distribution of invasive pathogens and pests and the plant hosts they impact. The database has been developed as a collaboration between the Forest Pathology and Mycology Laboratory at UC Berkeley and Calflora. CALinvasives will combine information on the dispersal potential of pathogen and pest threats, the current location of each, the hosts threatened, and their distribution, making it possible to assess the risk posed by each existing and emerging threat to California’s native...

Bait tests are very helpful for diagnosis of Phytophthora in for example soil, substrate, water, sediment, and rootball samples (Werres and others 2014). By attracting the motile zoospores of the Phytophthora species with the baits these pathogens can be separated from other organisms. Bait tests are simple and cost effective and - compared with other diagnostic techniques - they are much more independent on the varying sample quality. Furthermore, bait tests can be used for evaluating big sample quantities. Within the preparation of laboratory accreditation according to ISO standard...

The genus Phytophthora contains some of the most notorious plant pathogens affecting nursery crops. Given the recent emergence of the sudden oak death pathogen Phytophthora ramorum, particularly in association with Rhododendron spp., characterization of Phytophthora communities associated with this host in nursery environments is prudent. Many taxa may present symptoms similar to P. ramorum but we do not necessarily know their identity, frequency, and importance. Here, we present a survey of Phytophthora taxa observed from seven nurseries in the U.S. state of Oregon. Incidence and diversity...

Current regulations under the August 6, 2014 USDA APHIS Official Regulatory Protocol (Confirmed Nursery Protocol: Version 8.2) for Nurseries Containing Plants Infected with Phytophthora ramorum mandates the sampling of water in affected nurseries to demonstrate they are free of P. ramorum. Currently, detection of P. ramorum in these samples requires baiting periods followed by pathogen growth and/or expensive nucleic acid molecular detection methods. A rapid detection tool would greatly reduce the time, cost, and effort needed to demonstrate that nurseries are free of P. ramorum. To meet...

The National Ornamentals Research Site at Dominican University of California (NORS-DUC) is a research nursery that was established in 2009 to study invasive plant pathogens like Phytophthora ramorum, causal agent of sudden oak death and ramorum blight. In order to fulfill federal and state regulations, the possible movement of pathogens from the research site must be monitored using a sentinel plant system with host plants of P. ramorum (Rhododendron, Camellia, and Viburnum). Symptoms on the sentinel plants are studied using culturing, immunoassays, and sequence analysis. Symptom developmen...