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Plant, Pest & Disease
Plant Pest and Disease

Plant, Pest & Disease

Overview

Effective management of plant pests and diseases is critical to protecting both the nursery industry and our natural ecosystems. Regulatory actions, including quarantines and compliance agreements, play a crucial role in mitigating the spread of harmful pests and pathogens that can devastate plant species and disrupt trade.

At the Oregon Association of Nurseries (OAN), we work closely with state and federal agencies such as the USDA Animal and Plant Health Inspection Service (APHIS) to ensure that our members have the resources and support they need to navigate these complex regulations. From emerging threats like the Box Tree Moth and Phytophthora austrocedri to long-standing concerns like Sudden Oak Death and Emerald Ash Borer, OAN remains at the forefront of advocacy, research coordination, and education to safeguard the future of the industry.

This page provides updates on key legislative and regulatory developments, including quarantine measures, compliance guidelines, and the latest research efforts. Our goal is to keep growers informed and equipped to protect their operations while adhering to current regulations.

Quarantine Notices

CURRENT & EMERGING THREATS

Box Tree Moth

Voracious feeders, and in large numbers, they can strip the plants of their leaves entirely. Once defoliated, the caterpillars move on to feeding on the bark, which can ultimately kill the plant. Boxwoods are widely used as ornamental evergreen shrubs in landscapes across the United States. Learn more at aphis.usda.gov

What to look for:

  • Appearance: A box tree moth starts out as a lime-green caterpillar, with black stripes, white spots, hairs, and a shiny black head. Adult box tree moths generally have white wings with a thick brown border.
  • Brown leaves and defoliation: Missing sections of leaves or skeletonized leaves
  • Caterpillars and webbing: Young caterpillars hide among twigs and leaves, which can grow up to 1.5 inches.
  • Frass: Sawdust-like excrement from insects
  • Pupa: May be wrapped in webbing
  • Adult moths: They're difficult to spot, as they're most active at night.

View USDA APHIS signs and symptoms of box tree moth photo gallery

Latest news:

Phytophthora austrocedri

Phytophthora austrocedri is a soil and water-borne pathogen infecting woody species of the Cupressaceae family. Its center of origin is unknown. It was first reported causing widespread dieback and mortality of Austrocedrus chilensis in southern Argentina in 2007 by Greslebin and Hansen and subsequently reported causing extensive dieback and mortality of Juniperus communis in northern Britain.

It attacks conifers of the Cupressaceae family, including Austrocedrus, Juniperus, Chamaecyparis and Cupressus and potentially others. It also has the attention of Jared LeBoldus, forest pathologist at OSU, because it has serious implications for forest Cupressaceae including cypress, juniper, and cedar. Thus, there’s an incentive to keep it from spreading in nature as well as nurseries.

Dr. Nik Grunwald at the USDA Agricultural Research Service, an expert in Phytophthora species, will be leading a multiagency group of researchers coordinating a response to the recent detection of P. austrocedri in Oregon.

What to look for:

  • Discolored foliage: The first sign of decline in juniper is that the foliage will turn brown or reddish over some branches or most of the crown. The pathogen may attack the stem or individual branches, causing patches of bronze-colored foliage amongst healthy green foliage.
  • Discolored inner bark: When the outer bark of the tree is cut away at the infested area, it will reveal discolored inner bark, or phloem. The diseased tissue is usually a cinnamon brown color with yellow brownish lesion edges. Resin islands may be present. Healthy tissue, on the other hand, will be white.

Latest news:

Resources:

Latest updates on DiggerMagazine.com

Emerald Ash Borer

The emerald ash borer (EAB), an invasive wood-boring beetle from Asia, is responsible for the death and decline of tens of millions of ash trees in North America. EAB lays its eggs in the bark crevices of ash trees. The eggs hatch and the larvae burrow into the tree where they feed. This feeding is what damages the trees. We have detected EAB infestations in 36 States and the District of Columbia.

EAB is difficult to detect early when pest populations are small because damage to the trees is hidden under the bark and tree decline is gradual. The beetle is well-suited to our climate, is a good flyer, and spreads naturally. People contribute to the long-distance spread of the beetle when they move EAB-infested ash firewood, logs or nursery stock. EAB was first detected in North America in 2002 in southeast Michigan. Learn more

What to look for:

  • Appearance: EAB adults are metallic green with a coppery-red abdomen and about one-half inch long.
  • Signs of infestations: EAB larvae burrow into the tree and feed on the inner bark and phloem and creating S-shaped markings. They pupate in winter and emerge as adults in spring, leaving D-shaped exit holes. The adults remain active until the end of summer.
  • Activity: Adult beetles live for about three weeks. They are most active during the day, particularly when the weather is warm and sunny. To weather storms, they move to protected locations in bark crevices or cling to foliage.
  • Damage: Symptoms of an infestation may include dead branches near the top of ash trees, excessive branching on tree trunks and vertical cracks in tree bark.
  • Woodpecker Activity: Woodpeckers peel off the outermost layers of bark and punch their beaks through the remaining bark to eat larvae. If you see an increase in woodpecker activity, you may have EAB-infested trees.

Latest news:

Resources:

Latest updates on DiggerMagazine.com



MAJOR DISEASES

Sudden Oak Death (SOD)

Phytophthora ramorum is an invasive plant pathogen that causes sudden oak death, ramorum blight, ramorum dieback, and Phytophthora canker diseases. There is no cure for the diseases caused by P. ramorum. Preventing the movement of infected plants and materials is the best way to protect our forests and landscape plants.

The water mold, P. ramorum, is an invasive pathogen that can infect over 100 plant species (319.67 KB). In coastal California and southern Oregon, P. ramorum causes sudden oak death, a disease which has killed millions of trees, primarily tanoak and coast live oak. The pathogen also causes twig and leaf diseases in several common nursery and landscape plants. Learn more

What to look for:

Symptoms vary on different types of plants. They can include:

  • Trunk and branch cankers
  • Brown to black lesions on leaves
  • Twig dieback

OAN continues to work toward a national strategy for pest, plant and disease policies at the national level. Continued work with USDA and APHIS would require a major push at the western region and national levels. Sudden Oak Death (SOD) funding for private forest lands has been requested through USDA funding and could require effort on the appropriation side. 2008-09 funding would be $2.538 million with work necessary toward a line item for the 2010 budget cycle (established in 2009). To date, USDA has contributed $250,000 additional dollars for suppression of SOD. Oregon continues to be a national leader in the development of a systems approach to pest and disease issues facing the nursery industry. OAN is working with its national association, key nursery states and USDA to develop a model approach to deal with current and emerging pest and diseases.

Latest updates on DiggerMagazine.com



Boxwood Blight

Boxwood blight is a disease affecting several host plants including all Buxus species to varying degrees, with B. sempervirens being more susceptible. Other hosts include plants of the genera Pachysandra and Sarcococca. It is caused by Calonectria pseudonaviculata , a soilborne pathogen. Learn more

Latest updates on DiggerMagazine.com





RESEARCH & ADVOCACY

Ongoing Research Efforts

The Oregon Association of Nurseries (OAN) Research Committee plays a crucial role in advancing industry knowledge by identifying and prioritizing key research needs. Through close collaboration with the research community, the committee encourages targeted studies that address the most pressing issues facing nurseries today.

OAN partners with the Oregon Department of Agriculture (ODA) to award annual research grants, supported by a research assessment tied to ODA’s nursery license fees. Additionally, OAN administers the Shade Tree Disease Fund, which is entirely funded by donations from individuals and corporations, with 100% of contributions going toward research projects aimed at combating shade tree diseases.

Nursery Research



OAN's Advocacy Role

It is the core of the association to utilize all advocacy tools to support and defend the industry. This is done on many levels – Oregon Department of Agriculture, US Department of Agriculture – Animal Plant Health & Inspection Service (USDA-APHIS) along with partnerships with researchers at the USDA (Agricultural Research Service), Oregon State University, and industry partners such as the Horticultural Research Institute and AmericanHort. When an issue arises, turf goes out the window and the industry is resolute to problem solve. The OAN has significant reach at the state and national level and serves the membership every day.

Get Involved



RESOURCES FOR GROWERS

Systems Approach to Pest and Pathogen Prevention

Ensuring the health and vitality of nursery stock requires more than just reactive measures—it calls for a proactive, comprehensive strategy. The Oregon Association of Nurseries (OAN) promotes the use of a systems approach to pest and pathogen prevention, which is detailed in our Safe Procurement and Production Manual.

Safe Procurement and Production Manual

The systems approach focuses on evaluating and improving every step of nursery production, from propagation to final shipment, to reduce risks associated with pests and pathogens. By identifying and addressing high-risk areas before issues arise, growers can prevent the introduction and spread of harmful pests, ensuring the long-term health of their plants and the success of their business.

The Safe Procurement and Production Manual is a 106-page guide that outlines best practices for reducing risks throughout the nursery production process. It provides detailed instructions on every aspect of plant production, offering growers the tools to evaluate and optimize their operations.

Download the Safe Procurement and Production Manual

Key resources include:

By following the systems approach outlined in this manual, growers can ensure their operations are equipped to prevent outbreaks, protect their crops, and comply with current regulations.

Pacific Northwest Pest Management Handbooks



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The OAN is committed to supporting the nursery industry through comprehensive advocacy, education, and collaboration on issues related to plant pests and diseases. By working closely with state and federal agencies, research institutions, and our members, we strive to protect plant health and ensure the sustainability of nursery operations across the region.

Through proactive measures like the systems approach, ongoing research initiatives, and strong legislative efforts, OAN helps growers navigate complex regulatory landscapes while safeguarding their crops from harmful pests and pathogens. We invite our members to stay informed through our resources, take advantage of the best practices we promote, and continue contributing to the health of our industry.

Stay up to date on the latest developments and opportunities in plant health management with the OAN Member Update and Pest & Disease Alerts.

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