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Three questions with... David Karp

The ‘Fruit Detective’ and his Modern Citrus Cultivars Descriptive Database

No one can stay uninterested in fruit after a casual conversation with David Karp. The sheer vastness of David’s knowledge of fruit cultivars, the passion with which he talks about fruit qualities, and the rich vocabulary he uses to describe them cannot leave anyone unmoved. Depending on how the conversation goes, one might as well think him a biologist (for the depth of his knowledge), a chef (for the number of taste epithets in his vocabulary), a scientist (for his association with the UC Riverside and his contributions to horticultural sciences), or a farmer (to be fair, he is a partner in a fruit farm in the San Jose area). Indeed, David appears to have lived several lives – as a trader on Wall Street, as a journalist traveling the world in search for the best fruits for The New York Times and the Los Angeles Times, and, finally, as an academic and the ultimate ‘fruit detective’.

Roughly a year ago, David reached out to CIOPORA with several queries on plant IP rights. He was looking for any reliable records of PBR, plant patents, and trademarks in citrus for a major undertaking – the Modern Citrus Cultivars Descriptive Database. Recently, we caught up with David to check on the project’s development.

Photo: David Karp at the University of California, Riverside Citrus Variety Collection.

Photo credit: Andrea Bricco

CIOPORA (C): David, how did you come up with the idea for the Modern Citrus Cultivars Descriptive Database, and what is its main purpose?

David Karp (DK): As co-editor of the Register of New Fruit and Nut Cultivars, I was compiling a list of new citrus cultivars developed around the world, to help choose which ones to describe in the Register. I was able to download a file of all IP-protected citrus cultivars from the PLUTO database maintained by The International Union for the Protection of New Varieties of Plants (UPOV), but this source listed many cultivars generically as “citrus”, without specifying the fruit type, such as orange, lemon, mandarin hybrid, etc. To fill in the blanks in this field for fruit type or common name I started gathering information from plant patents, scientific articles, commercial descriptions, and other sources, thinking that in a few days I could annotate the whole list of ~1,000 cultivars. But as I made notes, I realized that all the information fields were interdependent. For example, to find scientific articles about a Japanese satsuma mandarin, one needed to have the cultivar name in Japanese characters. Gradually the scope expanded into a new model of pomological reference work, with 23 categories including cultivar names, synonyms, trademarks, common names, botanical names, intellectual property applications and grants, breeders and their affiliations, pedigrees, descriptions of trees and fruits, and bibliographical citations with links.

This work complements the website of the University of California, Riverside Citrus Variety Collection (CVC), which I helped put together over the past 15 years. That older website describes the CVC’s accessions, most of which are publicly available. However, most recent citrus cultivars, including some of great scientific and/or commercial importance, are IP-protected and not available for public collections to plant, but are nevertheless of great interest to citrus industry stakeholders, including breeders and other citrus researchers, IP professionals, growers, nurseries, packers, wholesalers, retailers, processors, foodservice – and the citrus-curious public, too! By systematic discovery and exploitation of available sources, I have gathered a wide range of information that in many cases would not otherwise be readily available – to give just one example, the description of a pummelo recently developed in China, based on a scientific article in Chinese.

C: Was it challenging to collect the IP title information for the project?

DK: I needed to find IP application and grant details (numbers and dates), and associated technical dossiers, such as DUS test reports with descriptions of trees and fruit. The PLUTO database provided a good starting point, but I wanted to find the original sources on which it was based, e.g., the plant variety rights gazettes and databases for each country or jurisdiction. UPOV provides a handy Directory of PVP Offices, but this often doesn’t include direct links to PVP gazettes and databases, which can be hard to find. Over time I found most but not all of what I was looking for, and listed the names and links in MCCDD’s Appendix D - Patent, PBR, and trademark journals, and databases.

PBR and plant patent dossiers are easy to find for some countries and jurisdictions, but quite difficult for others. Some issuers appear not to make any information available, while others vary considerably in the material they provide, such as photos, breeding pedigree, and morphological descriptions according to IPGRI descriptors or CPVO DUS protocols. Some countries charge for translation of and access to their PBR and DUS files.

One problem, common in scientific research, is that many source materials are in foreign languages. Over time I figured out how to find each cultivar’s name in its native language and script, search for authoritative documents, take screen grabs and perform optical character recognition as needed, and translate via Google translate. Doing this for hundreds of cultivars took a long time, but hopefully will shine a light on many previously obscure sources.

I still have much to learn. I am eager to interact with CIOPORA and UPOV experts as I continue to explore what information is available, where to find it, and how best to use it. I am happy to share this knowledge and hopeful that it will prove useful to other researchers.

C: How can breeders, including CIOPORA members, utilize the database right now and what are the next steps in the project’s development?

DK: The MCCDD home page is on the CVC website. Its primary content, the MCCDD database, is in an Excel file. Users can read it online, or download the file, which is easy to sort and search.

The MCCDD home page links to a detailed description of the work, with explanations of the choices I made. There are also five appendices with information that may be of interest to a wide range of researchers, such as a spreadsheet of North American plant patents and PBR for all pomological crops from 2016 onwards, searchable by cultivar name, crop, IP details, and date.

MCCDD is a work in progress, updated after the appearance of new information, such as plant patent or PBR application or grant details. In addition, I am trying to improve both the content and the format.

To improve the content, I hope to enlist the assistance of citrus experts in each country where new cultivars have originated. For recently developed cultivars I may reach out to the breeders themselves. I’d like to add more cultivars protected in non-UPOV jurisdictions. Ultimately, I’d like to obtain and include photographs of each cultivar, which would be of great interest and utility to both specialists and casual browsers.

The current Excel format is easy for me to compile and maintain, and good for users to search, but unwieldy for browsing – few people read Excel spreadsheets for pleasure! To make MCCDD both more robust and reader-friendly, I would like to transform it into a true searchable database like PLUTO, which would allow users to search by multiple criteria, such as Spanish clementines post 2010, or lycopene-pigmented sweet oranges. In addition, however, I’d like to provide one page for each cultivar, including synonyms, trademarks, sources, and PBR information from all jurisdictions. In that way, each page would be an authoritative reference for one cultivar and would be readily accessible via search engines. That is the case now for CVC pages, which are often the first resource that shows up in internet searches for a cultivar.


David Karp is an Assistant Specialist at the Department of Botany & Plant Sciences, University of California, Riverside. Contact:


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