On Oct. 7, 2005, as temperatures hit the mid-80s, a group of engineers, Aggies and others gathered on campus to witness history: The legendary UC-Blackwelder tomato harvester was formally being designated a historic landmark by the American Society of Agricultural and Biological Engineers. On that warm autumn day, the harvester became the society’s 45th historic landmark, joining such icons as John Deere’s steel moldboard plow, the McCormick Reaper, Eli Whitney’s cotton gin, the row-crop tractor and the self-propelled combine. In California, it was the sixth such landmark, along with the Holt track-type tractor and steep-slope combine, the Rainbird sprinkler, FMC’s continuous rotary sterilizer for canned goods and the roll-over protective structure for tractors — which also was developed, in part, at UC Davis.
The historic designation was a momentous occasion for three men who — while not as well known as their innovation — arguably saved California’s processed tomato industry in the 1960s. For those men — Jack Hanna, Coby Lorenzen and Steven Sluka — their story dates back to the 1940s.
In 1942, UC Davis vegetable crops researcher Hanna started breeding new tomato varieties that would ripen uniformly and could withstand mechanical harvesting. Seven years later, agricultural engineer Lorenzen joined Hanna in working to develop a mechanical tomato harvester. Parallel efforts by others, including a team led by an agricultural engineer and horticulturist at Michigan State University, eventually resulted in several different harvesting mechanisms. Engineering the equipment was no small challenge because tomato harvesting requires multiple functions, including cutting and lifting the vines, then separating the tomatoes from the vines. But in the late 1950s, another UC Davis agricultural engineer, Sluka, developed a key improvement — a vine separator — for Lorenzen’s machine.
The UC Davis team successfully tested their newly modified harvester on the Lester Heringer farm in Chico. Heringer was so impressed that he convinced the Blackwelder Manufacturing Co. of Rio Vista to commercialize the design. According to the plaque unveiled in 2005, the resulting machine “became the dominant tomato harvester in the world and revolutionized the industry.” In only a five-year-period, 1963–68, the methods for harvesting processing tomatoes in the U.S. changed from essentially all manual to primarily mechanical.
“Mechanical harvesting was controversial because it seemingly displaced human labor,” Bruce Hartsough, then-chair of the Department of Agricultural and Biological Engineering, said in an October 2005 interview. But by reducing harvesting costs by nearly one half, Hartsough said, the harvester eliminated an economic constraint on the U.S. processing tomato industry, resulting in large increases in tomato acreage and yield. Those increases, in turn, provided additional employment in field work, transportation and processing that more than offset the displaced harvesting jobs.
“The tomato harvester is a perfect example of the shared history of agricultural engineering and biology,” Hartsough said. “It required the parallel collaborative development of tomato varieties that were resistant to mechanical damage, were easily detached from the vine and ripened uniformly.”