Insecticide efficacy and emergence timing of the Douglas-fir twig weevil.

The Douglas-fir twig weevil (Cylindrocopturus furnissi Buchanan) (Coleoptera: Curculionidae) has recently emerged as a significant pest of Christmas trees grown in the Pacific Northwest United States. The larvae girdle and disfigure twigs, which adversely affects tree marketability. Trees produced for export are also routinely destroyed for phytosanitary reasons when C.

Physical characteristics of soil-biodegradable and nonbiodegradable plastic mulches impact conidial splash dispersal of Botrytis cinerea.

Botrytis cinerea causes gray mold disease of strawberry (Fragaria ×ananassa) and is a globally important pathogen that causes fruit rot both in the field and after harvest. Commercial strawberry production involves the use of plastic mulches made from non-degradable polyethylene (PE), with weedmat made from woven PE and soil-biodegradable plastic mulch (BDM) as emerging mulch technologies that may enhance sustainable production. Little is known regarding how these plastic mulches impact splash dispersal of B.

Detection and Molecular Phylogenetic-Morphometric Characterization of Causal Agent of Gray Bulb Rot of Tulips and Bulbous Iris.

Gray bulb rot of tulips and bulbous iris is caused by the soil-borne fungal pathogen, (). Sclerotia present in infected bulbs, as well as overwintering sclerotia in soil and field debris, are the primary sources of infection. A method for accurate and sensitive detection of from soil and infected bulbs, and estimation of inoculum threshold levels, is needed for the management of disease caused by this pathogen.

First report of leaf blight caused by Phytophthora ramorum on periwinkle (Vinca minor) in Washington State, USA.

Phytophthora ramorum (Werres, De Cock & Man in't Veld) was recovered from symptomatic foliage of periwinkle at a botanical garden in WA in March 2015. Symptoms were tan colored lesions with a dark brown margin visible on both surfaces of the leaf and were found on wounds or around leaf margins. Periwinkle is native to Europe and is commonly used for ground cover in ornamental landscapes.

Genetic analysis reveals unprecedented diversity of a globally-important plant pathogenic genus.

Genus Botrytis contains approximately 35 species, many of which are economically-important and globally-distributed plant pathogens which collectively infect over 1,400 plant species. Recent efforts to genetically characterize genus Botrytis have revealed new species on diverse host crops around the world. In this study, surveys and subsequent genetic analysis of the glyceraldehyde-3-phosate dehydrogenase (G3PDH), heat-shock protein 60 (HSP60), DNA-dependent RNA polymerase subunit II (RPB2), and necrosis and ethylene-inducing proteins 1 and 2 (NEP1 and NEP2) genes indicated that Botrytis isolates collected from peony fields in the United States contained more species diversity than ever before reported on a single host, including up to 10 potentially novel species.

A Novel Phagomyxid Parasite Produces Sporangia in Root Hair Galls of Eelgrass (Zostera marina).

The objective of this study was to identify the parasite causing the formation of root hair galls on eelgrass (Zostera marina) in Puget Sound, WA. Microscopic and molecular analyses revealed that a novel protist formed plasmodia that developed into sporangia in root hair tip galls and released biflagellate swimming zoospores. Root hair galls were also observed in the basal section of root hairs, and contained plasmodia or formed thick-walled structures filled with cells (resting spores).

Interactions Between Root Rotting Phytophthora, Abies Christmas Trees, and Environment.

Defining host-pathogen interactions between species of root-rotting Phytophthora and Abies in Christmas tree production areas is important for tailoring management activities on a regional scale and for developing molecular tools for identifying resistant host species. Classifying Abies species as resistant or susceptible is complicated by regional variation in abundance and aggressiveness of Phytophthora species and the influence of environment on symptom expression and host vigor. Because previous studies performed to assess host response to Phytophthora root rot (PRR) have focused on one or a few species of either the host or pathogen, a multifactorial experiment was conducted to assess the responses of seven species of Abies challenged with three isolates each of four Phytophthora species under contrasting temperature conditions.

Characterization of phenotypic variation and genome aberrations observed among Phytophthora ramorum isolates from diverse hosts.

Background: Accumulating evidence suggests that genome plasticity allows filamentous plant pathogens to adapt to changing environments. Recently, the generalist plant pathogen Phytophthora ramorum has been documented to undergo irreversible phenotypic alterations accompanied by chromosomal aberrations when infecting trunks of mature oak trees (genus Quercus). In contrast, genomes and phenotypes of the pathogen derived from the foliage of California bay (Umbellularia californica) are usually stable.

Botrytis euroamericana, a new species from peony and grape in North America and Europe.

A novel species of Botrytis isolated from peony in Alaska, USA, and grape in Trento District, Italy, was identified based on morphology, pathogenicity, and sequence data. The grape and peony isolates share sequence homology in the glyceraldehyde-3-phosphate dehydrogenase (G3PDH), heat shock protein 60 (HSP60), DNA-dependent RNA polymerase subunit II (RPB2), and necrosis- and ethylene-inducing protein 1 and 2 (NEP1 and NEP2) genes that place them in a distinct group closely related to B. aclada, a globally distributed pathogen of onions.

Comparison of Five Detection and Quantification Methods for Phytophthora ramorum in Stream and Irrigation Water.

Propagules of Phytophthora ramorum, the causal agent of sudden oak death (SOD) and ramorum blight, can be recovered from infested stream and nursery irrigation runoff using baiting and filtration methods. Five detection methods, including pear and rhododendron leaf baits, Bottle O' Bait, filtration, and quantitative polymerase chain reaction (qPCR) performed on zoospores trapped on a filter were compared simultaneously in laboratory assays using lab or creek water spiked with known quantities of P. ramorum zoospores.

First Report of a New Leaf Blight Caused by Phacidiopycnis washingtonensis on Pacific Madrone in Western Washington and Oregon.

In recent years, a leaf blight disease, consisting of browned, desiccated leaves occurring mainly in the lower parts of the canopy, has been observed during wet springs on Pacific madrone (Arbutus menziesii) in western Washington and Oregon. In May 2009 and 2011, severe outbreaks occurred and symptomatic leaves from madrones growing in the region were sampled to determine the causal agent. Two symptoms, leaf necrosis or blotching along the edges and tips of the leaves, and leaf spot, were observed.

Sydowia polyspora associated with current season needle necrosis (CSNN) on true fir (Abies spp.).

Current season needle necrosis (CSNN) has been a serious foliage disorder on true fir Christmas trees and bough material in Europe and North America for more than 25y. Approximately 2-4 weeks after bud break, needles develop chlorotic spots or bands that later turn necrotic. The symptoms have been observed on noble fir (Abies procera), Nordmann fir (A.

First Report of Phytophthora ramorum Infecting California Red Fir in California.

In May 2005, branches originating from five separate whorls below the terminal on a single California red fir (Abies magnifica) in a mixed grand fir (Abies grandis) and Douglas-fir (Pseudotsuga menziesii) Christmas tree plantation near Los Gatos, CA displayed wilting and dieback of new shoot growth. Brown dieback, delineated by needle loss, extended 6 to 8 cm into 1-year-old and sometimes 2-year-old growth. The ~7-year-old, 1-m tall tree was located near the edge of the plantation, beneath an overstory of California bay laurel (Umbellularia californica) trees that were infected with Phytophthora ramorum.

Population genetic analysis infers migration pathways of Phytophthora ramorum in US nurseries.

Recently introduced, exotic plant pathogens may exhibit low genetic diversity and be limited to clonal reproduction. However, rapidly mutating molecular markers such as microsatellites can reveal genetic variation within these populations and be used to model putative migration patterns. Phytophthora ramorum is the exotic pathogen, discovered in the late 1990s, that is responsible for sudden oak death in California forests and ramorum blight of common ornamentals.

Standardizing the nomenclature for clonal lineages of the sudden oak death pathogen, Phytophthora ramorum.

Phytophthora ramorum, the causal agent of sudden oak death and ramorum blight, is known to exist as three distinct clonal lineages which can only be distinguished by performing molecular marker-based analyses. However, in the recent literature there exists no consensus on naming of these lineages. Here we propose a system for naming clonal lineages of P.

Use of shaking treatments and preharvest sprays of pyrethroid insecticides to reduce risk of yellowjackets and other insects on Christmas trees imported into Hawaii.

Insects are commonly found by Hawaii's quarantine inspectors on Christmas trees imported from the Pacific Northwest. To reduce the risk of importing yellowjacket (Vespula spp.) queens and other insects, an inspection and tree shaking certification program was begun in 1990.

Spread of Heterobasidion annosum in Christmas Tree Plantations of the United States Pacific Northwest.

ABSTRACT The population structure of Heterobasidion annosum in the Pacific Northwest (PNW) Christmas tree plantations was estimated at two spatial scales to assess the relative importance of primary and secondary infection, colonization, and spread of the pathogen. Ninety-three isolates from single trees in 27 discrete mortality pockets and 104 isolates from 12 individual root systems of noble and Fraser fir trees were sampled near Mossyrock, Washington. Isolates were genotyped using somatic compatibility assays and microsatellite markers to determine the spatial scale at which dispersal of single genotypes (genets) was occurring.

Recovery Frequency of Phytophthora ramorum and Other Phytophthora spp. in the Soil Profile of Ornamental Retail Nurseries.

We tested the hypothesis that inoculum of the aboveground exotic plant pathogen Phytophthora ramorum would be limited to the organic layer (top layer of plant debris) of soils at infested retail nurseries located outside of the area where the pathogen has become established in the landscape. To test this hypothesis and compare inoculum levels of P. ramorum with levels of other Phytophthora spp.

Adhesion of Nongerminated Botrytis cinerea Conidia to Several Substrata.

Conidia of the plant pathogenic fungus Botrytis cinerea adhered to tomato cuticle and to certain other substrata immediately upon hydration. This immediate adhesion occurred with both living and nonliving conidia. Adhesion was not consistently influenced by several lectins, sugars, or salts or by protease treatment, but it was strongly inhibited by ionic or nonionic detergents.