Treesearch

Phytophthora ramorum has emerged repeatedly as four distinct clonal lineages in North America (lineages NA1, NA2, and EU1) and Europe (EU1 and EU2). Long-distance migration of P. ramorum is known to have occurred via the nursery trade. While most populations sampled in North American forests belong to the NA1 clonal lineage, nurseries have been shown to be infested with three lineages NA1, NA2 and EU1. EU1 and NA2 populations were discovered in environments around nurseries suggesting that nursery infestations could spread in the forest. It is therefore important to monitor populations for...

Phosphites have been used in the control of sudden oak death, however, the precise mode of action of these compounds is not fully understood. In order to study the action of phosphites in the context of naturally occurring host resistance, we designed an inoculation experiment on four open-pollinated tanoak families, previously defined as partially resistant. Stems of treatmentindividuals were sprayed with phosphite, and 7 days later, distal leaves were inoculated with the sudden oak death pathogen, Phytophthora ramorum. Leaves from treated and untreated control plants were harvested for...

Over the past two decades, many treatment methodologies have been proposed to therapeutically treat oaks infected with Phytophthora ramorum, causal agent of sudden oak death. Because of the coastal distribution of P. ramorum, one of the species at greatest mortality risk is coast live oak, Quercus agrifolia. Bark scribing, a treatment technique listed by the University of California Integrated Pest Management program to treat Phytophthora infected citrus trees, seemed to show promise, especially as it had a treatment history going back nearly 100 years. We therefore endeavored to test the...

In recent years, reports of Phytophthora detections have increased from plant production facilities supplying plant stock for restoration projects (Garbelotto and others 2018). When introduced into new natural habitats through infected plant stock, the potential for Phytophthora infection and spread is high. Monitoring of nursery stock is key to reducing new introductions into wildlands, however, sampling in nurseries is currently considered too expensive and complex to be performed on a large scale. This study was undertaken to determine if it would be possible to train ecological scent...

Sudden oak death (SOD), caused by a non-native pathogen Phytophthora ramorum has killed hundreds of thousands of tanoak (Notholithocarpus densiflorus) trees in Curry County, Oregon since it was first detected in 2001. With the expansion of the Phytophthora ramorum state quarantine in 2015, more landowners in Curry County are now under regulations to slow the spread of sudden oak death. Some landowners are under a state quarantine for the first time and in some cases are unaware of the state sudden oak death quarantine regulations. Since 2015, the European lineage (EU1) of P. ramorum has...

Dynamic geospatial simulations are valuable assets for exploring how an invasive pest or pathogen is likely to spread given a range of possible scenarios. In particular, they are powerful for conducting computational experiments to assess how management affects spread, as largescale management experiments may be impractical or unethical. Further, models can be used to generate no-management “control” comparisons, which do not exist with observed datasets. Geospatial simulations such as these have been developed to examine Phytophthora ramorum spread and impacts in California (Cunniffe and...

Phytophthora ramorum, the oomycete pathogen responsible for Sudden Oak Death (SOD) in California and Oregon forests, requires constant vigilance to detect and manage. Prior to 2011, the focus of Oregon-based management was complete eradication of all disease centers through removal of infected plant material. Despite intense eradication procedures, the disease continued to spread. Current Oregon management focuses on reducing the spread of SOD within Curry County, and preventing spread to neighboring counties (Goheen and others 2017).1 4 Previous research published in 2015 focused exclusive...

Sudden Oak Death (caused by Phytophthora ramorum) has been present in the Big Sur region since the mid-1990s (or earlier) and is the primary agent of mortality in tanoaks (Notholithocarpus densiflorus) there. Phytophthora ramorum also causes significant mortality in coast live oak (Quercus agrifolia) and Shreve oak (Quercus parvula var. shrevei) as well as ramorum blight in other species including California bay laurel (Umbellularia californica). A body of work has shown this changes forest composition and species abundance in Big Sur (Metz and others 2011). A plot network consisting of...

Sudden oak death (SOD), caused by Phytophthora ramorum, was first diagnosed as the cause of a lethal canker disease of coast live oak (Quercus agrifolia), California black oak (Q. kelloggii), and tanoak (Notholithocarpus densiflorus) in 2000. Between 2005 and 2009, we initiated multiple field studies to test strategies for reducing SOD impacts in stands of tanoak and susceptible oaks. In oak forests, California bay laurel (Umbellularia californica) is the primary source of P. ramorum inoculum that infects oaks, and proximity to bay greatly increases disease risk (Swiecki and Bernhardt...

It has been long determined that Umbellularia californica (California bay laurel) is the key transmissive host for the sudden oak death pathogen (SOD, Phytophthora ramorum) in mixedoak woodlands, however the parameters of bay to oak disease transmission have not been fully clarified (Garbelotto and others 2003). Here, we concisely present results of three studies: one clarifying the parameters of bay to oak transmission, and two testing whether two cost-effective approaches involving selective removal of a limited number of California bay laurel trees may reduce disease incidence in...