"Responding to Pine Wilt Disease Spread with Control Research... Protecting 1.6 Billion Pine Trees"

Research on the control of pine wood nematode disease is playing a foundational role in enhancing the effectiveness of on-site control measures. Since the initial outbreak of the disease in Korea, control research has been continuously conducted in phases and has been effectively utilized by the Korea Forest Service in establishing control policies.

Provided by Korea Forest Service

According to the Korea Forest Service and the National Institute of Forest Science on the 4th, pine wood nematode disease is caused by pine wood nematodes approximately 1 mm in size that penetrate pine tree tissues, blocking the flow of moisture and causing the pine trees to wither. The nematodes typically parasitize vector beetles such as the pine sawyer beetle and the northern sawyer beetle, entering the tree through wounds created when these beetles gnaw on the bark. Due to the characteristic that infected pine trees die 100%, the disease has earned the nickname “Pine AIDS.”

The first discovery of pine wood nematode disease in Korea was in 1988 in Busan. Since the initial detection, it is estimated that about 15 million pine trees have been infected. The damage peaked in 2014 with 2.18 million dead trees, then gradually decreased to 1.37 million in 2016, 690,000 in 2018, and 310,000 in 2021, before increasing again to 380,000 in 2022, indicating a resurgence in spread.

The Korea Forest Service and the National Institute of Forest Science have conducted research in three phases to prevent damage from pine wood nematode disease, achieving significant results.

Work to crush infected trees is in full swing at the pine wilt disease control site. Photo by Korea Forest Service

◆ Phase 1 Research (1989?2009) = This period saw a steady increase in infected trees, focusing intensively on “basic ecology and control technology development” of pine wood nematode disease.

At that time, guidelines for crushing, incinerating, and fumigating felled trees were established as the foundation for controlling the disease by removing infected trees. The low-toxicity fumigant “metam sodium (25%)” was also utilized to treat the rapidly increasing volume of felled trees.

The “clear-cutting” control method, which involves removing both infected and nearby uninfected trees to achieve control effects, was proposed during Phase 1 research. Additionally, studies on the life cycle of vector beetles supported the Korea Forest Service in determining the optimal timing for field control. The selection of highly effective preventive tree injection agents, “abamectin” and “abamectin benzoate,” also contributed to enhancing on-site control effectiveness during this phase.

◆ Phase 2 Research (2010?2015) = In 2014, the National Institute of Forest Science focused on “diversifying field support control technologies” to manage the surge of dead trees (2.18 million).

To reduce the volume of felled trees stored on-site, additional registrations were made for fumigants “dimethyl disulfide” and “metam sodium (42%),” and large-scale fumigation methods were developed to utilize dead trees. The insecticide “acetamiprid” was selected for large-area aerial control (which was suspended from February last year), and eco-friendly control research using vector beetle “pheromone traps” was conducted simultaneously.

Other achievements of Phase 2 include developing ground application methods for control agents and selecting the preventive tree injection agent “milbemectin,” which has a six-year residual effect, thereby establishing flexible field response strategies through various control technology developments.

◆ Phase 3 Research (2016?2023) = From 2016, damage from pine wood nematode disease gradually decreased. Research during this period focused on advancing surveillance, diagnosis, and control technologies. The duration of effectiveness for preventive tree injection agents was diversified between 2 to 4 years, and the selection of “combined tree injections” (such as abamectin benzoate + acetamiprid) capable of simultaneously controlling nematodes and vector beetles was achieved in Phase 3.

A representative achievement of this period was the development of a “portable gene-based pine wood nematode disease diagnostic kit” that can determine infection status within 30 minutes on-site without the need to transport samples to separate research institutions.

Phase 3 also initiated research on “breeding and distribution of nematode-resistant superior individuals” and established a “precision drone” pesticide application method to replace large-area aerial spraying, eliminating blind spots in severely damaged areas and leading-edge forest management.

Conceptual Diagram of Pine Wilt Disease Control Strategy. Provided by the Korea Forest Service

It is true that a series of achievements have been made through the phased research process that has continued since 1989. The National Institute of Forest Science, recognizing signs of a renewed spread of pine wood nematode disease, plans to set and pursue additional mid- to long-term research projects with a sense of urgency.

The mid- to long-term research projects include ▲“Advanced surveillance technology research” enabling rapid and accurate monitoring of wide areas through the agricultural and forestry satellite to be launched next year ▲“Damage spread characteristic research” to establish customized control strategies for special control zones such as Dalseong in Daegu, Pohang in Gyeongbuk, and Miryang in Gyeongnam ▲“Environmental risk assessment research of pesticides” to address concerns about environmental hazards ▲“Eco-friendly control technology research” ▲and the creation and distribution of clone preservation sites through propagation of nematode-resistant superior individuals.

Kim Incheon, Director of the Forest Pest Control Division at the Korea Forest Service, said, “We will do our best to produce highly effective research results for the field and policy of pine wood nematode disease to protect Korea’s 1.6 billion pine trees.”

This content was produced with the assistance of AI translation services.