Robert P. Kahn received his educational training in plant pathology in 1951 at the University of Illinois, Champaign-Urbana. He completed his doctoral degree working on asparagus rust and its causal agent Puccinia asparagi. Between 1952 and 1957, he was a supervisory plant pathologist at the Crops Division, Chemical Corps, U.S. Army, Frederick, Maryland. He investigated the virus infection process and the epidemiology of the rice blast disease. In 1957, he joined Plant Quarantine, Agriculture Research Service, which was transferred in 1970, to become Plant Protection and Quarantine, Animal and Plant Inspection Service (APHIS). He retired in 1985 but continued as a consultant in plant protection and quarantine until 2008, with contracts from APHIS, USAID, FAO, Commonwealth Agricultural Bureau International, and the World Bank. Also under agreements or contracts with APHIS or with other governments and/or grower associations, he completed 26 risk assessments for the export of commodities from other countries to the United States.
Kahn is an outstanding plant pathologist with significant contributions in the areas of regulatory research, biological updating of regulations, professional and public service, and administration. During his career as a regulatory plant pathologist, he published 99 papers and 30 technical reports. His most notable contributions as an author or editor include a three-volume set, Plant Protection and Quarantine, published by CRC Press (Volume I: Biological Concepts; Volume II: Selected Pests and Pathogens of Quarantine Significance; and Volume III: Special Topics). These books have served as monumental reference sources to the field of regulatory plant pathology. In addition, Kahn’s important review on “Exclusion as plant disease control strategy,” published in the Annual Review of Plant Pathology, provided a detailed and comprehensive evaluation of the use of exclusion as a regulatory plant pest control tool. More recently Kahn and S. B. Mathur were editors of another outstanding reference book entitled Containment Facilities and Safeguards for Exotic Plant Pathogens and Pests, published by APS PRESS. Kahn again advanced the field of regulatory plant pathology with the publication of his latest comprehensive reference book.
Kahn was one of the pioneer regulatory plant pathologists to recognize the need to develop methods for pest risk analysis for the export or import of commodities. In 1978, he published a paper outlining a framework and defining terms for pest risk analysis (Kahn, R. P. 1978. A Concept of Pest Risk Analysis. Eur. Mediterr. Plant Prot. Organ. Bull. 9:119-130). Kahn has also received national and international recognition for his accomplishments in the development of international standardized procedures for risk analysis and virus detection as a member of several international working groups for viruses of temperate fruit trees, small fruits, grapevine, legumes, vegetables, and ornamentals.
In 1957, at the U.S. Plant Introduction Station, Glenn Dale, Maryland. Kahn established the first USDA virus-indexing program, which included serology, for high-risk imported plants that are prohibited to the public under Quarantine 319.37 but are admissible under permit for scientific purposes after passing through quarantine at the Plant Introduction Station. Some of the high-risk plants that must pass through such a quarantine and are subject to virus indexing include Solanum, Prunus, Hibiscus, Datura, and Ipomoea species. Kahn also conducted research on the feasibility of using embryo or meristem tip culture and heat treatment to exclude viruses but allow entry of previously infected valuable plant germplasm.
With the introduction of the virus-indexing program, Kahn was able to improve the disease control strategies available to regulatory plant pathology and also provide an increased level of safeguards and exclude exotic plant pests. Examples include the nepoviruses Eucharis mottle virus and Tomato ringspot virus; the potyvirus Colombian datura virus; Amaryllis viruses; Dioscorea latent virus; and exotic strains of domestic viruses, such as potato viruses A, M, S, X, and Y, in imported germplasm. He detected the tobacco veinal necrosis strain of PVY in imported species of Solanum cardensii and S. andigenum and Potato spindle tuber viroid in imported germplasm. Kahn was awarded the Herbert Medal from the American Plant Life Society in recognition of his research on Amaryllis viruses.
Kahn has made significant contributions in professional and public service areas. He served on many APS committees, such as Seed Pathology (1978), International Cooperation (1978–1979), Regulatory Plant Pathology (chair [1974–1976], member [1965–1970, 1972–1976, 1982–1986]), and Virology (1969–1970), and as chair of the Subcommittee on the American Type Culture Collection (ATCC) for Viruses. As chair, he was instrumental in changing the decentralized and informal system of virus preservation at various university laboratories to a standardized system and centralized location at ATTC, Rockville, Maryland. Kahn was also an APHIS representative to the USDA Recombinant DNA Committee (1982–1985). He was a member of the British Society of Plant Pathology and has served as chair of the Seed Pathology Committee of the North American Plant Protection Organization (1980–1984).
In addition, he served as a scientific advisor to the Inter-African Phytosanitary Commission (1970–1974). Kahn’s contributions to the field of regulatory plant pathology in international standards, international plant protection research, publication of pest risk assessments, service to scientific societies and international plant protection organizations, and publication of his groundbreaking comprehensive books merit recognition of his outstanding accomplishments.