His concepts of seed-potato quality were implemented by the University of Idaho in a foundation seed program. Seed growers in the high-altitude, seed-producing areas of the state owe much to Marshall's vision and understanding of the value of certified seed.
His persistence in hanging on to practices that he believed in contributed much to the color and the legend of Joe Marshall. In his later years, he wore a mustache and was very frequently seen clad in bib overalls. He appeared to wear them proudly as the uniform of a man who has spent his life in agriculture and loved the Idaho potato.
The appreciation expressed for Joe Marshall's contributions in his own time was very gratifying to him in later years and especially the title of "Idaho Potato King," which he always enjoyed and cherished. He died in January 1964, at the age of 89.
A tribute was paid Joe Marshall when the potato industry-research center was established at the University of Idaho Experiment Station at Aberdeen. The modern laboratory office and greenhouse complex became known as the Joe Marshall Research Center. His name appears on the bronze plaque and a color picture of Joe Marshall inspecting a field of blossoming potatoes decorates the wall inside the entrance.
The contribution of men such as Marshall, who worked tirelessly and uncompromisingly for the betterment of the industry, would be extremely difficult to measure. But it is certain that Joe Marshall's contributions have earned for him a prominent place in the history of the Idaho potato industry.