Conifers in Crisis: �� scientist seeks solutions to widespread needle blight

John Thomason, a Mississippi State research technician, teaches Riley Simms, a junior forestry major from Tuscaloosa, Alabama, to measure tree core rings to track impacts of disease severity and management, like prescribed fire, on tree growth. (Submitted photo) — From right to left: John Thomason, a Mississippi State research technician, teaches Riley Sims, a junior forestry major from Tuscaloosa, Alabama, how to measure tree core rings to track impacts of disease severity and management, like prescribed fire, on tree growth. (Photo by John Riggins)

STARKVILLE, Miss.—Timber is a pillar of Mississippi’s economy. The third largest commodity in the state, it supports more than 70,000 jobs and produces an economic impact of approximately $13 billion for Mississippi. Despite the strength of the state’s trees and the industries resting on their sturdy limbs, a mysterious threat has taken root in pine stands across Mississippi, turning large swaths of pine forests brown.

Pictured is pine blight in a Mississippi forest (Submitted photo) — Pictured is pine blight in a Mississippi forest (Photo by John Riggins)

A Mississippi State scientist is on the scene, searching for answers.

John Riggins, professor in the Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, works diligently to understand why pine needle blight—a complex of several fungal species that kills pine needles, reducing tree health—is raging like wildfire through loblolly pine stands across Mississippi, Alabama and other Southeastern states.

The Mississippi Agricultural and Forestry Experiment Station entomologist contributes to a multi-state partnership established by the USDA Forest Service Southern Research Station, or SRS, to address recent reports of needle diseases throughout the Southeast.

“These pathogens are native but, historically, have not caused problems in stands of mature loblolly pine,” Riggins said. “In the past, this was only a problem in young longleaf seedlings and in nursery settings.”

Riggins is aware of anecdotal needle blight reports as far back as 2016. Today, he and his team assess the complex problem to determine its scope, when and where it occurs, the specific species of blight pathogens and their effects. They also investigate the potential roles of insects or other pathogens, which may take advantage of blight-stressed trees.

“Dr. Riggins’s work contributes to a regional research network that SRS initiated to effectively investigate the distribution, epidemiology and management strategies for loblolly pine needle diseases,” said Rabiu Olatinwo, SRS research plant pathologist. “The network will ultimately benefit the region's forest ecosystems, products sector and economy.”

Riggins and his team—including scientists from the Mississippi Forestry Commission, Auburn University, University of Georgia, Louisiana Tech and the University of Florida—initially approached the problem from a bird’s eye view—examining numerous satellite images of the pine stands. From those images, they are creating a map depicting affected acreage. They also partner with the �� Geosystems Research Institute in obtaining drone footage.

Kennedy Brooks, senior forestry major from Laurel, uses a laser hypsometer to measure tree height. (Submitted photo) — Kennedy Brooks, senior forestry major from Laurel, uses a laser hypsometer to measure tree height. (Photo by John Riggins)

The team, including students from �� and visiting scientists from France and Italy, gathers ground-based data, such as tree height and diameter measurements, growth from tree ring data and the openness of the canopy, using photogrammetric techniques. These efforts verify and quantify information from the remotely sensed images. Georeferenced data are uploaded from the field using cellphone apps.

The study also aims to identify onsite pathogens in real time, using what Riggins calls “tailgate genetics.” The scientists gather infected needle samples, processing and placing them into a battery-operated loop-mediated isothermal amplification, or LAMP, machine to identify DNA of suspected pathogens. In addition, strategically placed motorized traps collect spores from the air. A partnering Florida lab barcodes and quantifies the DNA.

Riggins said tree stands statewide are turning brown again as the fungus leaves its overwintering phase. Results will trickle in throughout the year. Historically, needle blight in mature longleaf pine stands was controlled with prescribed fire, and this winter, team partners will conduct controlled burns in loblolly stands to test this potential solution.

The �� scientist is developing outreach materials for landowners and managers, with expected availability later this year. For now, Riggins advises those seeing potential signs of blight to contact him, the MFC or their county extension office.

“We urge stakeholders to remain calm and know that while we can’t get answers overnight, we are working on them as quickly as we can,” Riggins said. “Forestry is a huge economic driver in the Southeast, and our working forests also provide essential services like recreation, clean air and drinking water. We’re trying to conserve and protect our environment as well as our industries.”

Scientists in the Mississippi Agricultural and Forestry Experiment Station conduct applied research to discover solutions to complex natural resource issues. To find out more about the station, visit mafes.msstate.edu.

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