UNIVERSITY PARK, Pa. — For almost 40 years, Rob Crassweller, professor of horticulture and extension tree-fruit specialist in Penn State’s College of Agricultural Sciences, has made impactful contributions to education, extension and research.
Crassweller is passing the mantle to a new generation of scientists and extension educators as he embarks on the next chapter of his life — retirement.
“Due to Rob’s leadership, the Penn State Extension tree-fruit extension educational program is considered the preeminent tree-fruit program in the East,” said Rich Marini, professor of horticulture. “His career has been one of service, and his work has been instrumental in bettering the industry, the Department of Plant Science, and the college.”
Crassweller grew up in Columbus, Ohio, where he spent his youth working at the Ohio State University golf courses. The experience inspired him to pursue a career where he could work outdoors. He enrolled at Miami University, in Oxford, Ohio, where he earned a bachelor’s degree in botany. He also holds a master’s degree and a doctorate in horticulture from Ohio State University.
While in graduate school, he had the opportunity to meet faculty from Penn State’s Fruit Research and Extension Center in Biglerville when they visited Ohio State. Crassweller stayed in contact with them while working at his first job at one of the University of Georgia’s agricultural research stations. Those relationships — and an interest in living closer to family in Ohio — prompted Crassweller to join Penn State in 1983.
“The mid-Atlantic tree-fruit industry was a large and prosperous industry, and Penn State was a leading horticulture institution with a strong and well-respected faculty,” he said. “My new colleagues at Penn State were young, dynamic and well known in the mid-Atlantic region.”
Crassweller quickly became a leader in the extension tree-fruit program and served as the program co-chair. He conducted in-service training for county-based extension educators working with tree fruit, participated in field days, led in-state and out-of-state orchard tours, and gave presentations at meetings around the state on related topics.
His extension activities had an international component — Crassweller participated in 16 international assignments, working with fruit growers to implement production practices to improve their operations. He also served as a short-term educator/consultant in Ukraine, Ecuador and Swaziland.
Crassweller melded his applied research and extension activities by participating in several multistate initiatives, including helping to lead a project evaluating apple cultivars that received a research award. He also developed an innovative, computer-aided system for apple thinning, and his studies led to fertilizer recommendations for tree-fruit growers based on leaf-tissue analysis.
In 2013, Crassweller obtained funding to join the Network for Environment and Weather Applications developed by Cornell University. The information provided by weather monitoring stations in the program helps growers determine the proper time to apply chemical apple thinners.
“As a team, we developed the first expert systems for orchard decision management in the country,” Crassweller said. “This effort involved horticulture, plant pathology, entomology and agricultural engineering. Our extension team also developed educational programs that provided breadth and depth of information.”
Countless apple growers have planted orchards throughout the state based on scientific knowledge Crassweller has generated from those projects, noted Ben Keim, of Boyertown, a fifth-generation grower and past president of the State Horticultural Association of Pennsylvania.
“As a colleague and educator, Dr. Crassweller always was very easy to work with,” said Keim, a graduate of the college. “He was able to approach a topic and look at it from all possible sides to figure out what might be the best solution. Horticulture is fascinating; many techniques can achieve the same outcome depending on the grower’s preference.”
Crassweller is editor of Pennsylvania Fruit News and is a contributing writer for Penn State Extension’s Fruit Times newsletter. He also helped coordinate the Penn State Tree Fruit Production Guide, which has evolved from a 50-page publication to more than 500 pages. The guide received several awards from the American Society for Horticultural Science, the most recent one in 2020-21.
Crassweller chairs the tree fruit program for the Mid-Atlantic Fruit and Vegetable Conference, which attracts more than 2,500 growers from many states and Canada annually. He also conceived and initiated the annual Mid-Atlantic Cider Competition and served as treasurer and business manager for the American Pomological Society from 1990 through 2016.
Although he did not have a teaching appointment, Crassweller volunteered to teach a tree-fruit science course. Many of his students went on to careers in the tree-fruit industry as growers, extension educators in Pennsylvania and scientists at other universities. He also advised undergraduate students, many of whom were from fruit-growing families, and stayed connected with them after graduation.
“He is an excellent teacher,” Marini said. “His labs were hands-on — the students visited commercial orchards, made cider, pruned trees and had apple variety fruit tastings. When one of his advisees graduated, Rob attended graduation and presented them with a pomology book.”
Crassweller received many accolades, including the 2018 American Society for Horticultural Science Outstanding Extension Educator Award. The award recognizes an educator who has had a distinguished and outstanding career as an extension specialist in horticultural science for 10 years or more.
He also was selected as a Kellogg Foundation National Leadership Fellow in 1991, received the Outstanding Grower Award from the State Horticultural Association of Pennsylvania in 2014, and the Outstanding Horticultural Educator award from the American Society for Horticultural Science in 2018.
Kari Peter, associate research professor of tree-fruit pathology, who worked with Crassweller for almost a decade, described him as an exceptional leader. She also appreciated his “willingness to step outside of his comfort zone” and be a regular guest on the “Dr. Tree Fruit and Don” podcast, which she co-hosts with tree-fruit extension educator Don Seifrit.
“Rob has so much wisdom and experience, and I value him as a mentor,” Peter said. “He always is willing to answer questions, share his knowledge and be a go-to for resources. He has a great rapport and is well respected among the tree-fruit growers in the state and beyond. We congratulate him on his well-earned retirement.”
Crassweller said the most rewarding part of his career was working with the faculty, students and three generations of mid-Atlantic fruit growers and industry members.
“I have known grandparents, fathers and mothers, and children of orchard growers,” he said. “Another highlight was being able to teach the tree-fruit production class to multiple generations. However, I will miss the chance to mentor the fourth generation.”