Monitoring Using a Sentinel Plant System Reveals Very Limited Aerial Spread of Phytophthora ramorum From Infected Ornamental Plants in a Quarantine Research Nursery

Pastalka, Tomas; Rooney-Latham, S.; Kosta, Kathleen; Suslow, Karen; Huffman, Vernon; Ghosh, Sibdas; Schweigkofler, Wolfgang

doi:10.1094/php-rs-16-0050

Cited by 3 publications

(1 citation statement)

References 19 publications

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“…Lewis [42] and Parke and Lewis [43] found that P. ramorum could be translocated in the vascular system of rhododendrons when planted in potting soil inoculated with the pathogen. Natural infections with Phytophthora species on sentinel plants at NORS-DUC were observed only during the rainy season with a spike from January to March, with no symptom development during the dry summer months [44]. Non-symptomatic growth of P. ramorum in the foliage of woody plants has been reported by Denman et al [45] and McCartney et al [46].…”

Section: Qpcr Test Confirmationmentioning

confidence: 76%

Use of Foliar Chemical Treatments to Induce Disease Resistance in Rhododendrons Inoculated with Phytophthora ramorum

Ramsey¹,

Freebury

Newman

et al. 2022

Glob. J. Agric. Innov. Res. Dev

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A field study was conducted at the National Ornamental Research Site at Dominican University California (NORS-DUC). The study goal was to evaluate three chemical inducers applied as foliar treatments for controlling Phytophthora ramorum, on Rhododendron x ‘Cunningham’s White’ nursery plants. The inducers were chlorine dioxide (ElectroBiocide), hydrogen peroxide (OxiDate 2.0), and acibenzolar-s methyl (Actigard). Water samples from the electrostatic sprayer were measured for three physicochemical water properties. Visual assessment of plant foliage, based on the Horsfall- Barratt scale, was conducted at three and five months after chemical treatments. Foliar fluorescence (Fv/Fm) was measured over three dates. The success of P. ramorum inoculations were determined using qPCR methods. Visual assessment across both months showed no signs of P. ramorum infection or chemical injury symptoms. However, P. ramorum infection vis-à-vis qPCR analysis was confirmed. The September Fv/Fm results revealed that all the chemical inducer treatments were equivalent to the water treatment, except for Actigard. The qPCR results were in general agreement with the Fv/Fm results indicating that the rhododendrons were successfully inoculated with P. ramorum but were non-symptomatic. The electrostatic sprayer ionized the water droplets, resulting in increased Fv/Fm values for the water treatments 90 days after application. There was a three-month delay in fluorescence responses to the most effective chemical applications, indicating that woody plants may need to be monitored over the long term to determine accurate responses to foliar treatments.

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Section: Qpcr Test Confirmationmentioning

confidence: 76%

Use of Foliar Chemical Treatments to Induce Disease Resistance in Rhododendrons Inoculated with Phytophthora ramorum

Ramsey¹,

Freebury

Newman

et al. 2022

Glob. J. Agric. Innov. Res. Dev

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Transmission of the Invasive Pathogen Phytophthora ramorum from Symptomatic to Healthy Host Plants During a Five-Year Period in California

Schweigkofler

Pastalka

Abeysekara

et al. 2022

Plant Health Progress

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Reliable data on the transmission of airborne plant pathogens are crucial for the development of epidemiological models and implementation of management strategies. The short-distance vertical transmission of the forest pathogen Phytophthora ramorum from a symptomatic California bay laurel (Umbellularia californica) to healthy containerized rhododendrons (Rhododendron caucasicum × R. ponticum var. album) was monitored for five winters (2016/17 to 2020/21) in a field experiment in Northern California. Transmission events were observed during four winters at a frequency of 1 to 17 per season, but not during the extremely dry winter of 2020/21, and were positively correlated to total rainfall rates. The first leaf symptoms were detected around mid-December and reached the highest numbers in January of most years. Only limited symptom development was observed in the spring, with the last detections in May. The exposure time (the time between the first rainfall after placing a bait plant under the bay laurel and development of symptoms) varied between 3 and over 150 days, with an average between 14 and 21 days. P. ramorum was detected from water samples collected from the canopy of the symptomatic California bay laurel. No horizontal pathogen spread was detected from symptomatic to healthy rhododendrons placed at a distance of 2 to 6 m.

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Monitoring the Reoccurrence of Fire Blight and the Eradication Efficiency of Erwinia amylovora in Burial Sites of Infected Host Plants Using Sentinel Plants

Park¹,

Song²,

Vu³

et al. 2022

Res. Plant Dis

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The fire blight caused by Erwinia amylovora (Ea) was first reported in 2015 in Korea, and the disease has rapidly spread to 22 regions until 2021. In Korea, all host plants in the apple and pear orchards where fire blight occurred should be eliminated and buried by the Plant Protection Act. To prevent the spread of the disease, all burial sites were prohibited from planting the new host plants for the next three years. To confirm the eradication efficiency of Ea and the reoccurrence of fire blight, the surveillance facilities were established on three burial sites from 2019 to 2020 in Anseong-si, Gyeonggi-do, and Chungju-si, Chungcheongbuk-do. As host plants, five apple trees of fire blight-susceptible cultivar ‘Fuji’, were planted in each facility. All facilities were enclosed with fences and nets and equipped with two CCTVs, motion sensors, and several other sensors for recording weather conditions to monitor the environment of the sentinel plants in real-time. The sentinel plants were checked for the reoccurrence of fire blight routinely. Suspicious plant parts were collected and analyzed for Ea detection by loop-mediated isothermal amplification polymerase chain reaction and conventional polymerase chain reaction. Until November 2022, Ea has not been detected in all sentinel plants. These results might support that the burial control of infected plants in soil works efficiently to remove Ea and support the possibility to shorten the prohibition period of host plant establishment in the burial sites.

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Monitoring Using a Sentinel Plant System Reveals Very Limited Aerial Spread of Phytophthora ramorum From Infected Ornamental Plants in a Quarantine Research Nursery

Cited by 3 publications

References 19 publications

Use of Foliar Chemical Treatments to Induce Disease Resistance in Rhododendrons Inoculated with Phytophthora ramorum

Use of Foliar Chemical Treatments to Induce Disease Resistance in Rhododendrons Inoculated with Phytophthora ramorum

Transmission of the Invasive Pathogen Phytophthora ramorum from Symptomatic to Healthy Host Plants During a Five-Year Period in California

Monitoring the Reoccurrence of Fire Blight and the Eradication Efficiency of Erwinia amylovora in Burial Sites of Infected Host Plants Using Sentinel Plants

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