University of Vermont

Mark Mazzola Solves Apple Replant Disease of Pacific Northwest and Gives Back to His Roots

Graduate alum profile

Mark Mazzola, Research Plant Physiologist with the USDA Agricultural Research Service in Wenatchee, Washington
Mark Mazzola, Research Plant Physiologist with the USDA Agricultural Research Service in Wenatchee, Washington

Research Plant Pathologist Mark Mazzola (FOR ’82, MS-FOR ’85) has been elected Fellow of the American Phytopathological Society (APS), the highest award by the Society given annually to less than 0.1% of its members.  For the past 18 years, at the USDA Agricultural Research Service (ARS) in Wenatchee, Washington, Mark has helped re-grow the Pacific Northwest apple industry through development of ecologically-based disease control measures using his education and experience in plant pathology and soil microbial ecology.

Mark is excited about his Fellow award for which he will be recognized at a special ceremony during the APS annual meeting in August. “It represents recognition by my peers of the significance of my accomplishments to the field of plant pathology,” he states. But perhaps more important to him is being able to give back— in acknowledgement of those who helped him to achieve his career goals.

Growing up in a single parent family of nine children in the suburbs of Boston, older brothers introduced Mark to the wonders of the backcountry at Tuckerman’s Ravine in New Hampshire.  Summer work at a state forest through the Youth Conservation Corps incited him to study forestry at UVM in the late 1970s.

Struggling to pay out-of-state tuition his senior year, he took a semester off to work at a local supermarket stocking shelves at night, until former Professor Dale Bergdahl, who saw great potential in Mark, took him under his wing. With Dale’s assistance, Mark applied for and was awarded a small research grant to study a fungus causing a Christmas tree disease, and he worked in Dale’s forest pathology lab while finishing his Bachelor’s degree.

Under Dale’s mentorship, Mark studied this very same balsam fir pathogen for his Master’s research, trapping fungal spores at UVM’s Wolcott Research Forest and learning the life cycle and ecology of the fungus to better aid Vermont Christmas tree growers in managing the disease. Mark’s career was off and running, but he saw the opportunities for employment in forest pathology diminishing nationally and instead switched to studying the ecology of agricultural systems.

With Professor R. James Cook at Washington State University (WSU), Mark worked on biological control of soilborne wheat diseases. After a post-doctoral stint at Kansas State University and another with the USDA ARS Root Disease and Biological Control Research Unit in Pullman, Washington, in 1995 Mark stepped smoothly into his current position at the USDA ARS Tree Fruit Research Laboratory in Wenatchee.

His timing couldn’t have been better…or worse. “The state of the apple growing industry in the Pacific Northwest at that time was hellaciously bad,” describes Mark. “Growers were ripping out trees left and right.  There had been no renovation to the system for many years, and the industry had not moved to new apple varieties to keep up with the worldwide markets and was still producing 70% Red Delicious.”

“The price of apples plummeted and for four or five years, we were in a bad economic situation,” adds Mark.  Growers pulled out thousands of acres of trees and replanted new varieties, and today orchards contain a more diversified mix of apple varieties with only 30 to 35% Red Delicious. 

Unfortunately, there was more to the story. Because of the vast acreage being replanted, a common disease called Apple Replant Disease became an epidemic.

"For me, it was fortuitous,” admits Mark. Replant is caused by a soilborne disease, Mark’s expertise, but no one understood the microbiology actually causing the disease in apple trees.  Growers simply treated soil with environmentally hazardous chemical fumigants such as methyl bromide, now phased out, in hopes of controlling the causal agents.

Mark began with suppositions of past scientists who hinted at certain microorganisms that might be involved.  Conducting selective microbial elimination trials with elevated temperatures or narrow target biocides, Mark looked at growth responses of apple trees and narrowed down the culprits to a few soil fungi and a soil nematode (microscopic roundworm).

Drawing on what he’d learned with wheat pathogens, he began investigating the local soil microbial community to see what natural organisms could be encouraged to suppress the pathogens. Using Brassica seed meal, a bi-product of biodiesel production, as a biological soil amendment in apple orchards, Mark has successfully created a more resilient soil ecosystem, one that suppresses the ability of pathogens to re-infest apple trees and has helped to re-establish the apple industry in the Northwest.

Even more important to him is what he’s achieved by mentoring students, much like Dale did for him.  Mark is an adjunct faculty member in the Plant Pathology and the Crop and Soil Science departments at WSU and has advised many graduate students and postdoctoral associates in his lab, including Antonio Izzo (UVM ’90) now on the faculty of Elon University in North Carolina.

“I have had so many more experiences by working with students,” he says.  “They bring fresh perspectives to the lab and often stimulate me to think about things from a different viewpoint.” Mark’s students come from all over the world, including South Africa where Mark collaborates with faculty at Stellenbosch University in studies of soil microbiology in tree fruit, vineyard, and potato production systems.

Because of Dale’s mentorship, in 2006 when Dale retired from the Rubenstein School, Mark initiated and is the continued benefactor for the Dale Bergdahl Scholarship given annually to a junior Forestry student in financial need who exemplifies Dale’s desired qualities in a student of forestry.  This year’s recipient is Teague Henkle (FOR '14), a licensed pilot, leader of the UVM student chapter of the Society of American Foresters, captain of the UVM Woodsmen Team, and student researcher at the University's Proctor Maple Research Forest where he conducted a study on the tapping of paper birch for syrup.

Mark and his wife Michelle Simpson Mazzola (RM ’83) also contribute to Give UVM, a new scholarship for beyond first-year students at UVM who need financial help to continue with their final years.  “I came from a low income out-of-state family and was personally paying every penny of my UVM education,” explains Mark. “I’d like to help someone else in a similar financial situation.”

Mark and Michelle live in Leavenworth, Washington, where Michelle also works from her business Resource Solutions. Through grant writing, she helps organizations for developmentally disabled adults and works with small communities to develop infrastructure such as hospitals, libraries, and fire stations.  The couple also works closely with Share Community Land Trust to build homes for modest income families, and Mark is on the board of the Leavenworth Community Farmer’s Market.

The couple can step out the back door of their home and go any direction in the heart of the 2.1-million-acre Wenatchee National Forest. They hike, cross-country ski, travel, and return regularly each spring and autumn to enjoy Vermont.