scholarly journals Phytophthora Introductions in Restoration Areas: Responding to Protect California Native Flora from Human-Assisted Pathogen Spread

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1291
Author(s):  
Susan J. Frankel ◽  
Christa Conforti ◽  
Janell Hillman ◽  
Mia Ingolia ◽  
Alisa Shor ◽  
...  
Keyword(s):  
Work Group ◽  
Pilot Project ◽  
Phytophthora Species ◽  
Plant Production ◽  
Native Plant ◽  
Collective Actions ◽  
Hybrid Species ◽  
Native Flora ◽  
Nursery Stock ◽  
Plant Nursery

Over the past several years, plantings of California native plant nursery stock in restoration areas have become recognized as a pathway for invasive species introductions, in particular Phytophthora pathogens, including first in the U.S. detections (Phytophthora tentaculata, Phytophthora quercina), new taxa, new hybrid species, and dozens of other soilborne species. Restoration plantings may be conducted in high-value and limited habitats to sustain or re-establish rare plant populations. Once established, Phytophthora pathogens infest the site and are very difficult to eradicate or manage—they degrade the natural resources the plantings were intended to enhance. To respond to unintended Phytophthora introductions, vegetation ecologists took a variety of measures to prevent pathogen introduction and spread, including treating infested areas by solarization, suspending plantings, switching to direct seeding, applying stringent phytosanitation requirements on contracted nursery stock, and building their own nursery for clean plant production. These individual or collective actions, loosely coordinated by the Phytophthoras in Native Habitats Work Group ensued as demands intensified for protection from the inadvertent purchase of infected plants from commercial native plant nurseries. Regulation and management of the dozens of Phytophthora species and scores of plant hosts present a challenge to the state, county, and federal agriculture officials and to the ornamental and restoration nursery industries. To rebuild confidence in the health of restoration nursery stock and prevent further Phytophthora introductions, a voluntary, statewide accreditation pilot project is underway which, upon completion of validation, is planned for statewide implementation.

scholarly journals PhytophthoraSpecies Are Common on Nursery Stock Grown for Restoration and Revegetation Purposes in California

Plant Disease ◽  
2019 ◽  
Vol 103 (3) ◽  
pp. 448-455 ◽  
Author(s):  
S. Rooney-Latham ◽  
C. L. Blomquist ◽  
K. L. Kosta ◽  
Y. Y. Gou ◽  
P. W. Woods
Keyword(s):  
North America ◽  
Phytophthora Species ◽  
Molecular Techniques ◽  
Crown Rot ◽  
Native Plant ◽  
Nursery Stock ◽  
Plant Nursery ◽  
Root And Crown Rot ◽  
Symptomatic Tissue ◽  
First Time

Phytophthora tentaculata was detected for the first time in North America in 2012 in a nursery on sticky monkeyflower plant (Diplacus aurantiacus) and again in 2014 on outplanted native plants. At that time, this species was listed as a federally actionable and reportable pathogen by the USDA. As a result of these detections, California native plant nurseries were surveyed to determine the prevalence of Phytophthora species on native plant nursery stock. A total of 402 samples were collected from 26 different native plant nurseries in California between 2014 and 2016. Sampling focused on plants with symptoms of root and crown rot. Symptomatic tissue was collected and tested by immunoassay, culture, and molecular techniques (PCR). Identifications were made using sequences from the internal transcribed spacer (ITS) rDNA region, a portion of the trnM-trnP-trnM, or the atp9-nad9 mitochondrial regions. Phytophthora was confirmed from 149 of the 402 samples (37%), and from plants in 22 different host families. P. tentaculata was the most frequently detected species in our survey, followed by P. cactorum and members of the P. cryptogea complex. Other species include P. cambivora, P. cinnamomi, P. citricola, P. hedraiandra, P. megasperma, P. multivora, P. nicotianae, P. niederhauserii, P. parvispora, P. pini, P. plurivora, and P. riparia. A few Phytophthora sequences generated from mitochondrial regions could not be assigned to a species. Although this survey was limited to a relatively small number of California native plant nurseries, Phytophthora species were detected from three quarters of them (77%). In addition to sticky monkeyflower, P. tentaculata was detected from seven other hosts, expanding the number of associated hosts. During this survey, P. parvispora was detected for the first time in North America from symptomatic crowns and roots of the nonnative Mexican orange blossom (Choisya ternata). Pathogenicity of P. parvispora and P. nicotianae was confirmed on this host. These findings document the widespread occurrence of Phytophthora spp. in native plant nurseries and highlight the potential risks associated with outplanting infested nursery-grown stock into residential gardens and wildlands.

An accreditation program to produce native plant nursery stock free of Phytophthora for use in habitat restoration

2021 ◽  
Author(s):  
Tedmund J. Swiecki ◽  
Elizabeth A. Bernhardt ◽  
Susan J. Frankel ◽  
Diana Benner ◽  
Janell Hillman
Keyword(s):  
Best Management Practices ◽  
Habitat Restoration ◽  
Management Practices ◽  
Pilot Program ◽  
Native Plant ◽  
Best Management ◽  
Nursery Stock ◽  
Plant Nursery ◽  
Nursery Production ◽  
Integrated Program

Widespread Phytophthora infections have been discovered in nursery stock used in California restoration plantings. In response, nursery Phytophthora best management practices (NPBMPs) designed to exclude Phytophthora from nursery plants were developed to address the need for clean planting stock in restoration projects. A pilot program to implement the systematic use of the NPBMPs, Accreditation to Improve Restoration (AIR), was developed and started in 2018. As of 2020, 13 northern California restoration nurseries have been evaluated and five have met all the program requirements. In 564 tests conducted over four years with a sensitive leachate baiting protocol, no Phytophthora was detected from over 20,000 nursery plants produced in compliance with the NPBMPs. In comparison, Phytophthora was detected in 25% of tests conducted on partially-compliant stock, and in 71% of tests from nurseries following few or no NPBMPs. The AIR pilot program has demonstrated that container stock free of detectable Phytophthora can be reliably produced by adhering to an integrated program of clean nursery production practices. To obtain Phytophthora-free plants for habitat restoration, informed clients were willing to pay increased costs required to produce NPBMP-compliant nursery stock.

scholarly journals Phytophthora pathogens threaten rare habitats and conservation plantings

2020 ◽  
pp. 53-65
Author(s):  
Susan J. Frankel ◽  
Janice Alexander ◽  
Diana Benner ◽  
Janell Hillman ◽  
Alisa Shor
Keyword(s):  
Plant Species ◽  
Sudden Oak Death ◽  
Native Plant ◽  
Botanic Gardens ◽  
Nursery Stock ◽  
Plant Nursery ◽  
Container Plant

Phytophthora pathogens are damaging native wildland vegetation including plants in restoration areas and botanic gardens. The infestations threaten some plants already designated as endangered and degrade high-value habitats. Pathogens are being introduced primarily via container plant nursery stock and, once established, they can spread to adjacent areas where plant species not previously exposed to pathogens may become infected. We review epidemics in California – caused by the sudden oak death pathogen Phytophthoraramorum Werres, De Cock & Man in ‘t Veld and the first USA detections of P. tentaculata Kröber & Marwitz, which occurred in native plant nurseries and restoration areas – as examples to illustrate these threats to conservation plantings.

scholarly journals A Comparison of Irrigation-Water Containment Methods and Management Strategies Between Two Ornamental Production Systems to Minimize Water Security Threats

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2558 ◽  
Author(s):  
Andrew Ristvey ◽  
Bruk Belayneh ◽  
John Lea-Cox
Keyword(s):  
Water Quality ◽  
Irrigation Water ◽  
Capital Investment ◽  
Plant Pathogens ◽  
Production Systems ◽  
Water Security ◽  
Plant Production ◽  
Water Quantity ◽  
Return Water ◽  
Plant Nursery

Water security in ornamental plant production systems is vital for maintaining profitability. Expensive, complicated, or potentially dangerous treatment systems, together with skilled labor, is often necessary to ensure water quality and plant health. Two contrasting commercial ornamental crop production systems in a mesic region are compared, providing insight into the various strategies employed using irrigation-water containment and treatment systems. The first is a greenhouse/outdoor container operation which grows annual ornamental plants throughout the year using irrigation booms, drip emitters, and/or ebb and flow systems depending on the crop, container size, and/or stage of growth. The operation contains and recycles 50–75% of applied water through a system of underground cisterns, using a recycling reservoir and a newly constructed 0.25 ha slow-sand filtration (SSF) unit. Groundwater provides additional water when needed. Water quantity is not a problem in this operation, but disease and water quality issues, including agrochemicals, are of potential concern. The second is a perennial-plant nursery which propagates cuttings and produces field-grown trees and containerized plants. It has a series of containment/recycling reservoirs that capture rainwater and irrigation return water, together with wells of limited output. Water quantity is a more important issue for this nursery, but poor water quality has had some negative economic effects. Irrigation return water is filtered and sanitized with chlorine gas before being applied to plants via overhead and micro-irrigation systems. The agrochemical paclobutrazol was monitored for one year in the first operation and plant pathogens were qualified and quantified over two seasons for both production systems. The two operations employ very different water treatment systems based on their access to water, growing methods, land topography, and capital investment. Each operation has experienced different water quantity and quality vulnerabilities, and has addressed these threats using a variety of technologies and management techniques to reduce their impacts.

scholarly journals Wild Bee Conservation within Urban Gardens and Nurseries: Effects of Local and Landscape Management

2019 ◽  
Vol 12 (1) ◽  
pp. 293 ◽  
Author(s):  
Monika Egerer ◽  
Jacob Cecala ◽  
Hamutahl Cohen
Keyword(s):  
Species Richness ◽  
Land Cover ◽  
Plant Species ◽  
Crop Production ◽  
Plant Production ◽  
Native Plant ◽  
Landscape Features ◽  
Wild Bee ◽  
Bee Conservation ◽  
Local Habitat

Across urban environments, vegetated habitats provide refuge for biodiversity. Gardens (designed for food crop production) and nurseries (designed for ornamental plant production) are both urban agricultural habitats characterized by high plant species richness but may vary in their ability to support wild pollinators, particularly bees. In gardens, pollinators are valued for crop production. In nurseries, ornamental plants rarely require pollination; thus, the potential of nurseries to support pollinators has not been examined. We asked how these habitats vary in their ability to support wild bees, and what habitat features relate to this variability. In 19 gardens and 11 nurseries in California, USA, we compared how local habitat and landscape features affected wild bee species abundance and richness. To assess local features, we estimated floral richness and measured ground cover as proxies for food and nesting resources, respectively. To assess landscape features, we measured impervious land cover surrounding each site. Our analyses showed that differences in floral richness, local habitat size, and the amount of urban land cover impacted garden wild bee species richness. In nurseries, floral richness and the proportion of native plant species impacted wild bee abundance and richness. We suggest management guidelines for supporting wild pollinators in both habitats.

scholarly journals Insights from invasion ecology: Can consideration of eco-evolutionary experience promote benefits from root mutualisms in plant production?

AoB Plants ◽  
2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Josep Ramoneda ◽  
Johannes Le Roux ◽  
Emmanuel Frossard ◽  
Cecilia Bester ◽  
Noel Oettlé ◽  
...  
Keyword(s):  
Mycorrhizal Fungi ◽  
Crop Production ◽  
Biotic Interactions ◽  
Plant Production ◽  
Mineral Nutrient ◽  
Gene Pools ◽  
Native Plant ◽  
Crop Domestication ◽  
Mutualistic Symbiosis

Abstract Mutualistic plant–microbial functioning relies on co-adapted symbiotic partners as well as conducive environmental conditions. Choosing particular plant genotypes for domestication and subsequent cultivar selection can narrow the gene pools of crop plants to a degree that they are no longer able to benefit from microbial mutualists. Elevated mineral nutrient levels in cultivated soils also reduce the dependence of crops on nutritional support by mutualists such as mycorrhizal fungi and rhizobia. Thus, current ways of crop production are predestined to compromise the propagation and function of microbial symbionts, limiting their long-term benefits for plant yield stability. The influence of mutualists on non-native plant establishment and spread, i.e. biological invasions, provides an unexplored analogue to contemporary crop production that accounts for mutualistic services from symbionts like rhizobia and mycorrhizae. The historical exposure of organisms to biotic interactions over evolutionary timescales, or so-called eco-evolutionary experience (EEE), has been used to explain the success of such invasions. In this paper, we stress that consideration of the EEE concept can shed light on how to overcome the loss of microbial mutualist functions following crop domestication and breeding. We propose specific experimental approaches to utilize the wild ancestors of crops to determine whether crop domestication compromised the benefits derived from root microbial symbioses or not. This can predict the potential for success of mutualistic symbiosis manipulation in modern crops and the maintenance of effective microbial mutualisms over the long term.

scholarly journals Morphological and Genetic Variation among Four High Desert Sphaeralcea Species

HortScience ◽  
2012 ◽  
Vol 47 (6) ◽  
pp. 715-720 ◽  
Author(s):  
Chalita Sriladda ◽  
Heidi A. Kratsch ◽  
Steven R. Larson ◽  
Roger K. Kjelgren
Keyword(s):  
Genetic Variation ◽  
Geographic Distance ◽  
Morphological Characteristics ◽  
Classification Model ◽  
Consumer Confidence ◽  
Canonical Variate ◽  
Native Plant ◽  
Intermountain West ◽  
Plant Nursery ◽  
Voucher Specimens

The herbaceous perennial species in the genus Sphaeralcea have desirable drought tolerance and aesthetics with potential for low-water use landscapes in the Intermountain West. However, taxonomy of these species is ambiguous, which leads to decreased consumer confidence in the native plant nursery industry. The goal of this study was to test and clarify morphological and genetic differentiation among four putative Sphaeralcea species. Morphological characteristics of the type specimens were used as species references in canonical variate analysis to generate a classification model. This model was then used to assign putative species names to herbarium voucher specimens and to field-collected voucher specimens to clarify genetic variation among species. Field specimens were also classified using Bayesian cluster analyses of amplified fragment length polymorphism (AFLP) genotypes. Sphaeralcea coccinea (Nutt.) Rydb. and S. grossulariifolia (Hook. & Arn.) Rydb. formed a composite group morphologically and genetically distinct from the S. munroana (Douglas) Spach and S. parvifolia A. Nelson composite group. Each composite group displayed genetic isolation by geographic distance. Also, morphological traits of S. munroana and S. parvifolia correlated to geographic distance. Taken together these results suggest that our samples represent two sympatric yet reproductively isolated groups. Distinguishing between these two Sphaeralcea composite groups can create greater consumer confidence in plant material developed for use in Intermountain West low-water landscaping.

scholarly journals Phytophthora Species Associated with Plants in Constructed Wetlands and Vegetated Channels at a Commercial Plant Nursery Over Time

2019 ◽  
Vol 29 (6) ◽  
pp. 736-744
Author(s):  
Garrett A. Ridge ◽  
Natasha L. Bell ◽  
Andrew J. Gitto ◽  
Steven N. Jeffers ◽  
Sarah A. White
Keyword(s):  
Plant Species ◽  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Wetland Plants ◽  
Plant Production ◽  
Alternanthera Philoxeroides ◽  
Runoff Water ◽  
Commercial Plant ◽  
Plant Nursery ◽  
Irrigation Runoff

Constructed wetlands have been used for decades in agricultural settings to remediate nutrients and other agrichemicals from irrigation runoff and drainage; however, little is known about the presence and distribution of Phytophthora species within irrigation runoff water being treated in constructed wetlands. Therefore, we collected plant samples from within vegetated runoff collection channels and treatment stages of two constructed wetland systems receiving irrigation runoff at a commercial plant nursery in Cairo, GA, to determine if roots of wetland plants were infested by species of Phytophthora. Samples were collected 12 times, at 1- to 2-month intervals, over a 19-month period, from Mar. 2011 through Sept. 2012. The sample period covered all four seasons of the year, so we could determine if the association of Phytophthora species with roots of specific plant species varied with season. Approximately 340 samples from 14 wetland plant species were collected, and 22 isolates of Phytophthora species were recovered. Phytophthora species were typically isolated from plants in channels receiving runoff water directly from plant production areas; Phytophthora species were not detected on plants where water leaves the nursery. No seasonal patterns were observed in plant infestation or presence of species of Phytophthora. In fact, Phytophthora species were rarely found to be associated with the roots of the wetland plants collected; species of Phytophthora were found infesting roots of only 6.5% of the 336 plants sampled. Species of Phytophthora were not found to be associated with the roots of golden canna (Canna flaccida), lamp rush (Juncus effusus var. solutus), duckweed (Lemna valdiviana), or sedges (Carex sp.) during the study period. The exotic invasive plant species marsh dayflower [Murdannia keisak (33% of samples infested)] and alligatorweed [Alternanthera philoxeroides (15% of samples infested)] were found to have the first and third highest, respectively, incidences of infestation, with smooth beggartick (Bidens laevis) having the second highest incidence of samples infested (22%). Management of invasive species in drainage canals and constructed wetland systems may be critical because of their potential propensity toward infestation by Phytophthora species. Plant species recommended for further investigation for use in constructed wetlands to remediate irrigation runoff include golden canna, marsh pennywort (Hydrocotyle umbellata), pickerelweed (Pontederia cordata), and broadleaf cattail (Typha latifolia). The results from this study provide an important first look at the associations between species of Phytophthora and wetland plants in constructed wetland systems treating irrigation runoff and will serve to further optimize the design of constructed wetlands and other vegetation-based treatment technologies for the removal of plant pathogens from irrigation runoff.

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