Hazard Analysis for Phytophthora Species in Container Nurseries: Three Case Studies

Abstract

<jats:p><jats:italic>Phytophthora</jats:italic> species cause crop losses and reduce the quality of greenhouse and nursery plants. <jats:italic>Phytophthora</jats:italic> species can also be moved long distances by the plant trade, potentially spreading diseases to new hosts and habitats. Phytosanitary approaches based on quarantines and endpoint inspections have reduced, but not eliminated, the spread of <jats:italic>Phytophthora</jats:italic> species from nurseries. It is therefore important for plant production facilities to identify potential sources of contamination and to take corrective measures to prevent disease. We applied a systems approach to identify sources of contamination in three container nurseries in Oregon, California, and South Carolina. Surface water sources and recaptured runoff water were contaminated with plant pathogenic species at all three nurseries, but one nursery implemented an effective disinfestation treatment for recycled irrigation water. Other sources of contamination included cull piles and compost that were incorporated into potting media, infested soil and gravel beds, used containers, and plant returns. Management recommendations include preventing contact between containers and contaminated ground, improving drainage, pasteurizing potting media ingredients, steaming used containers, and quarantine and testing of incoming plants for <jats:italic>Phytophthora</jats:italic> species. These case studies illustrate how recycled irrigation water can contribute to the spread of waterborne pathogens and highlight the need to implement nursery management practices to reduce disease risk.</jats:p>

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

“…Outplanted nursery stock is not the only means by which restoration sites may become infested by Phytophthora. For example, Phytophthora may be present in materials used in plant installations, such as compost used as mulch [26]. Many restoration sites in California have previous land uses, such as cropland, orchards, Christmas tree farms, or other development, that may have residual Phytophthora infestations [11,27].…”

“…Species detected included P. cactorum, P. xcambivora, P. crassamura, P. syringae, and P. sp. kelmania, all species which have been detected in nursery stock [12,25,26]. No Phytophthora was detected from 34 samples of C. ferrisiae and other plants located upslope or beyond the drainage area below the 1993 planting.…”

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

“…Disease Management Solutions: Parke et al [37] describe how they applied a systems-type hazard analysis to identify sources of contamination for Phytophthora species in three container nurseries in Oregon, California, and South Carolina. Their procedure [37] is a modification of the hazard analysis of critical control points (HACCP) approach designed to ensure food safety in food processing facilities. Critical control points are defined as the best stages in a production process, where significant hazards of pathogen contamination can be prevented or reduced.…”

“…Parke et al [37] noted that surface water sources and recaptured runoff water were contaminated with plant pathogenic species at all three nurseries, but one nursery implemented an effective disinfestation treatment for recycled irrigation water. Other sources of contamination included cull piles and compost that were incorporated into potting media, infested soil and gravel beds, used containers, and plant returns.…”

Clean WateR3: Reduce, Remediate, Recycle—Using Transdisciplinary Science to Help Specialty Crop Producers Conserve Water and Resources

“…The eight articles in this series expand the body of information available to growers, researchers, and extension professionals related to efficient use of water and agrichemicals, contaminant management (pesticide, nutrient, and plant pathogen), the water footprint of plant producers, and opportunities to enhance adoption of water treatment practices. Some of the information resources developed include technologies that can help growers 1) increase water use efficiency and reduce pesticide movement (Abdi and Fernandez, 2019;Poudyal et al, 2019), 2) select effective management practices (Mack et al, 2019), 3) remove contaminants from irrigation runoff (Garcia Chance et al, 2019;Ridge et al, 2019), and 4) understand critical control points for mitigating disease and pesticide movement at grower production facilities (Parke et al, 2019;Ridge et al, 2019). Additional socioeconomic information resources were developed to help research and extension professionals understand how water use (application, consumption, and footprint) changes by region and operation (Knight et al, 2019) and how to identify opportunities to present information to stakeholders to encourage adoption and continued use of underused treatment technologies or practices (Lamm et al, 2019).…”