Insight No. 6

“Sometimes the roots of scientific revolutions are found in the most unlikely places.”

Author: Mani Skaria, Ph.D.
Professor Emeritus, Texas A&M–Kingsville
President & CEO, US Citrus
Production Date: August 31, 2025

Executive Summary

This Inside Story reveals a hidden chapter in citrus history. While Dr. Richard Hensz is celebrated as the father of the Texas red grapefruit—creator of Star Ruby and Rio Red—few know his pivotal role in mentoring a young Spanish scientist, Luis Navarro, during a USAID mission. Navarro’s academic journey at the University of California under Dr. Toshio Murashige, combined with his friendship with Florida technician Chet Roistacher, gave birth to shoot-tip grafting (STG), the foundation of clean citrus worldwide. This method revolutionized citrus by removing viruses from planting material, spreading from California to Florida, Israel, Spain, Turkey, and South Africa. Texas was the last to adopt it, in 1988, with Dr. Mani Skaria bringing the program to the Texas A&M-Kingsville Citrus Center. A personal photograph from that year captures Hensz, Skaria, Roistacher’s family, and a young Ronnie Skaria—today the CEO of US Citrus. This Inside Story blends science, serendipity, and legacy, reminding us that breakthroughs often grow from unexpected encounters, friendships, and shared vision.

Narrative

Dr. Richard Hensz is remembered as the father of the Texas red grapefruit. His releases, Star Ruby and Rio Red, transformed the citrus industries not only in Texas but also in Israel, Turkey, and South Africa. His name appeared in national newspapers like the Washington Post and Wall Street Journal. Yet, behind his public acclaim lay an untold story that only came to light after his passing.

During his overseas mission as Director of a USAID project in Spain, Hensz worked to strengthen Spanish agricultural science. Among his tasks was identifying promising young talent. One day, he encountered a teenager with long hair, a guitar, bell-bottom pants, and a cigarette—Luis Navarro. Despite the carefree exterior, Hensz saw potential in him and recruited Navarro for study at the University of California.

In California, Navarro studied under Dr. Toshio Murashige, the Japanese scientist who pioneered plant tissue culture. At the same time, Navarro met Chet Roistacher, a Florida technician fond of cigars, violin, and banjo. Despite their different backgrounds, the two struck up a friendship. Over music and discussions, they explored an idea: could the virus-free shoot tip of a citrus plant be grown into a clean, healthy tree?

Using Murashige’s nutrient media, Navarro and Roistacher proved it possible. By grafting the tiny meristem tip onto rootstock under sterile conditions, entire citrus plants could be regenerated free of systemic viruses. This method, called shoot-tip grafting (STG), was a breakthrough. California established the first clean citrus program, providing disease-free foundation stock that could be multiplied indefinitely. The innovation spread to Florida, Israel, Spain, Turkey, and beyond. South Africa built much of its citrus industry on the foundation of Star Ruby and clean plant material.

India had its own parallel developments through Dr. H. Maheshwari, who showed how coconut water could nurture plant cells and protoplasts, laying groundwork for tissue culture. Globally, the pieces of plant science were converging, but it was the meeting of Navarro, Murashige, and Roistacher that brought clean citrus to life.

Texas, however, was late to adopt. In 1988, when Dr. Mani Skaria joined the Texas A&M-Kingsville Citrus Center, he worked with Roistacher to finally bring certified clean citrus to the state. By then, Dr. Hensz was director of the center—and fittingly, Skaria would be the last faculty member Hensz appointed. Navarro and Roistacher both visited Texas to help establish the program.

A personal photograph from that year captures the moment: at Dr. Skaria’s first home in Edinburg, Texas, Hensz and his wife Betty, Mrs. Roistacher, and the Skaria family stand together. Chet himself took the photo. Decades later, the little boy in that photo—Ronnie Skaria—now leads US Citrus as CEO, carrying the vision of clean citrus into a new generation.

The hidden story of clean citrus is not just about science. It is about vision, friendship, and legacy. It shows how a hippie guitarist, a cigar-smoking violinist, a Japanese pioneer, and a Texas grapefruit breeder together reshaped the future of citrus. And it reminds us that sometimes, the roots of revolutions are found in the most unlikely places.

Closing Tagline

“Clean citrus wasn’t just a scientific method—it was a friendship, a vision, and a legacy carried forward.”