Virginia Tech secures $5.7 million USDA grant to combat fire blight

Every year, the United States suffers an estimated $100 million in losses of apple, pear, and other pome fruit crops to fire blight, a destructive disease caused by the bacterium Erwinia amylovora. Experts predict more damaging fire blight epidemics in the coming years.

Virginia Tech Assistant Professor Srdjan Acimovic of the College of Agriculture and Life Sciences is leading a team of researchers from seven of the nation’s top apple and pear-producing states in a multipronged effort to help growers manage fire blight at all its stages and stop its spread. The work is supported by a $5.7 million grant from the U.S. Department of Agriculture (USDA) National Institute of Food and Agriculture.

“We want to create the next generation of management tools for fire blight,” Acimovic said. “Our project is the first to address fire blight at all stages of the disease – from blossom blight to shoot blight to cankers on wood. We aim to revolutionize fire blight management, providing sustainable solutions for growers while ensuring the economic and environmental viability of the pome fruit industry."

Apples – whether fresh, canned, juiced, or dried – are the most popular fruit in the U.S. More than 11 billion pounds are grown each year in all 50 states, producing approximately $23 billion annually for the national economy.

However, fire blight takes a significant bite out of growers’ crop yields and profits. Costs of fire blight removal from infected orchards range from $67 to $2,134 per hectare. This is on top of the regular costs for preventive blight control, which can range from $527 to $1,354 per hectare annually. 

In the past decade, a perfect storm of conditions has contributed to fire blight’s rise. Warmer, wetter weather has created a more hospitable environment in which the bacterium can thrive. More profitable high-density orchard planting practices have enabled the disease to spread faster. And first-line treatments have lost their efficacy due to the bacterium’s increased resistance to antibiotics.

Acimovic is a tree fruit and specialty crop pathologist at the Alson H. Smith Jr. Agricultural Research and Extension Center, a Virginia Tech facility in Winchester well-known for its research contributions to plant pathology directly improving the quality, nutrition, health, and safety of the nation’s commercial fruit system.

To help with the project, he’s partnering with experts from Virginia Tech, Carnegie Mellon University, Michigan State University, Washington State University, Oregon State University, Cornell University, the University of Virginia, and Connecticut’s Agricultural Experiment Station. 

“Together, our research team of 15 scientists represents 92 percent of U.S. apple-producing states,” Acimovic said. “Our team will leverage expertise in robotics, machine learning, plant pathology, genetics, diagnostics, epidemiology, microbiomics, molecular biology, disease management, economics, and more to provide growers with critically needed effective control options that address all stages of fire blight disease.”

Fire blight – which earned its name for causing scorched, blackened areas of infection on trees – has three stages. It first appears in the spring, when the bacteria Erwinia amylovora infect blossoms on flowering trees, resulting in blossom blight and fruit loss. From there, the infection spreads to the shoots, causing shoot blight.

Eventually, the bacterium invades the wood tissue of branches and tree trunk causing cankers. Cankers – visible as dead zones of wood bark – harbor deadly bacteria that can hibernate during the winter and spread in the spring to new trees. The canker infections can easily invade the trunk and roots, killing the tree.

Acimovic’s team has multiple objectives for the four-year project:

• Improved fire blight canker mapping and detection. The team will use an unmanned ground vehicle with advanced stereo camera technology to produce detailed 3D orchard maps. They will then train artificial intelligence to recognize and highlight areas with fire blight canker to aid growers in their removal during winter.
• Better understanding of the pathogen behind fire blight. Scientists will work to increase knowledge of Erwinia amarlovora at a molecular level, investigating how it adapts to survive the winter in cankers and then reactivates in the spring to infect new trees.  
• New tools to fight fire blight. Researchers will develop and optimize specific antibacterial enzymes, yeasts, chemicals, and other biocontrol agents that show promise in combating fire blight on flowers and shoots. They also will explore avenues to increase plant immunity and the effectiveness of existing spray treatments.
• Field tests and industry engagement. The team has cultivated a large network of growers from throughout the U.S. who are partnering to test the new management tools and treatments. An advisory board composed of producers and industry stakeholders will offer feedback and guidance throughout the project.
• Economic analysis. Economic feasibility studies and cost modeling will identify the most cost-effective tools for growers resulting from this project.
• Extension and outreach. Extension agents in each participating state will present and share new fire blight management tools, practices, and materials with producers in English and Spanish, using a variety of in-person education programs and media channels. 

“We hope to provide growers with a holistic program for fire blight that enables them to detect and control all fire blight disease stages at once,” Acimovic said. “Our ultimate goal is to provide cost-effective tools to ensure the sustainability of America’s favorite fruit.”