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Watermelon Research and Development Group

Report from 1999 Annual Meeting

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Joint Report

CUCURBITACEAE’98, Pacific Grove, California
December 1, 1998


19th ANNUAL MEETING, Memphis, Tennessee
January 31, 1999

  • Benny D. Bruton, Chairman
    US Department of Agriculture
    Agricultural Research Service
    Lane, Oklahoma 74555
    [Voice] 580-889-7395 [Fax] 580-889-5783

Meeting Summary, June, 1999

  • The Watermelon Research and Development Working Group (WRDWG) met during the Cucurbitaceae’98 Meetings on Tuesday, December 1, 1998 in Pacific Grove, California. The meeting was held at the Asilomar Conference Center in conjunction with the Cucurbitaceae’98. More than 50 people were present and many more turned away because of seating capacity. Seven research reports were presented generating a lot of discussion.
  • The Annual Meeting of the WRDWG was on Sunday, January 31, 1999 in Memphis, Tennessee. The meeting was held at the Peabody Hotel in conjunction with The Southern Association of Agricultural Scientists (S.A.A.S.), the Southern Region American Society for Horticultural Sciences (SR: ASHS) and the Southern Division: American Phytopathology Society (SD: APS). We had excellent attendance with more than 50 people present at the meeting. Six research reports, a status report on watermelon germplasm, and a short film on research projects supported by the National Watermelon Promotion Board were presented to the group stimulating much interest and discussion among the participants.
  • The WRDWG has continued to grow in attendance and influence since its inception. The group has grown from three people in 1982 to more than 50 people in 1999. Dr. Gary Elmstrom was Chairman of the group from about 1982 through 1992. Dr. Ray Martyn was Chairman of the group from 1993 until 1997. We are now a very dynamic group with the common goal of expanding knowledge for the watermelon industry. Consequently, we are indebted to both Dr. Elmstrom and Dr. Martyn for their leadership.

I. Research Updates

  • One of the more difficult chores that the Chairman has to do is take notes of the research presentations and make sense out of it later. These are brief summaries of the presentations. At the end of each summary, it will be noted which meeting the information was presented. You are encouraged to contact the individual scientist if you need additional information.
  • Dr. George Boyhan [], University of Georgia, discussed the Web Page being developed for the Watermelon Research and Development Working Group. Dr. Boyhan has done a lot of work to get the Web Page up and running. We are indebted to him for that. Thanks a lot.
  • Mr. Ron Kothera [] and Dr. Anthony Keinath [], Department of Plant Pathology and Physiology, Clemson University. They are studying the Phoma spp.-Didymella bryoniae complex. There are three distinct groups of fungi that can cause confusion for those working on the gummy stem blight pathogen (Didymella bryoniae). They have developed PCR primers (three) to differentiate between Phoma cucurbitacearum (Didymella bryoniae), Phoma I, and Phoma II. Phoma II (has sexual stage) which can be very confusing in culture. There are dramatic differences in the ability of these fungi to cause disease on watermelon. The PCR can also be used for testing seed for presence of the respective fungi. [Cucurbitaceae’98 and 19th Annual Meeting]
  • Dr. Warren Roberts [], Department of Horticulture, Oklahoma State University is working toward standardization of variety evaluations and data accumulation. The objective is to form a groundwork for a coalition of workers that would allow for increased uniformity and increased information exchange throughout the watermelon industry. Details need to be worked out as to the specific format, data, and evaluations that will be required. [19th Annual Meeting]
  • Mr. Sam Pair [], USDA-ARS, Lane, Oklahoma, gave an overview of the research on Yellow Vine of watermelon. The disease is associated with a phloem-limited bacterium that is likely vectored by a leaf-hopper insect according to his research. The main characteristic symptom is a honey-brown discoloration of the phloem. The disease was first observed in Texas and Oklahoma watermelons in 1991. However, in 1998, the disease was confirmed by PCR in Tennessee on watermelon and pumpkin. Consequently, the watermelon crop in the southeastern U S may also be at risk. [Cucurbitaceae’98 and 19th Annual Meeting]
  • Dr. John Damicone [], Department of Entomology and Plant Pathology, Oklahoma State University is working on control of foliar disease of watermelons with an emphasis on anthracnose. His research has shown that Topsin plus Dithane gave good control as well as Bravo alone. In 1998, Xanthomonas campestris pv. cucurbitae was responsible for severe defoliation of pumpkin. The disease caused up to 30% defoliation in watermelon in 1997. This is a disease new to Oklahoma and not much is known about the epidemiology. [19th Annual Meeting]
  • Dr. Todd Wehner [], Department of Horticulture, North Carolina State University, is testing more than 1200 watermelon PIs for resistance to Papaya ring spot virus type W (PRSV-W). PRSV-W was formerly called watermelon mosaic virus 1 (WMV-1). Inoculation methods were developed for the purpose of screening the germplasm. Tests were run to determine the optimum seedling stage for inoculation ranging from the cotyledon to the four true leaf stage. Results indicated that the rub method on the first true leaf was the most satisfactory method to establish symptoms. The most virulent isolate was selected for further evaluations. Testing should be completed by spring of 1999. Dr. Wehner has a list of diploid inbreds (or OPs) that he is collecting seed and pedigree information on. If you can assist, please contact Todd at his E-mail address for the list and any information that you may have. [Cucurbitaceae’98 and 19th Annual Meeting]
  • Dr. Joe Norton, Department of Horticulture, Auburn University, gave an overview of his watermelon breeding program over the years which included such releases as AU-Jubilant, AU Sweet Scarlet, and others. He noted that the honey bee population in Georgia and many other areas of the United States is critically low. At the present rate, honey bees may become an endangered species which ultimately is impacting cucurbit production. [Cucurbitaceae’98 and 19th Annual Meeting]
  • Dr. Tom Zitter [], Department of Plant Pathology, Cornell University, discussed pathogenicity and virulence of Didymella bryoniae. Other nonpathogenic or weakly virulent Phoma species are sometimes isolated from infected tissue, complicating identification of the pathogen. PCR primers can be used to differentiate between Phoma cucurbitacearum (Didymella bryoniae) and other Phoma spp. Twenty D. bryoniae isolates, collected from cucurbits, all caused similar disease reaction on inoculated cucurbits indicating similarity among Didymella isolates in level of virulence. [Cucurbitaceae’98]
  • Dr. Bruce Carle [], University of Florida, discussed the situation with race 2 of Fusarium oxysporum f. sp. nevium in watermelon. At present, there are no known commercial cultivars with adequate resistance to this race. Using PI 296341, various crosses have been made to incorporate Fusarium race 2 resistance into horticulturally acceptible material. Good progress is being made in several lines. His virus resistance work in watermelon is also progressing nicely. [Cucurbitaceae’98]
  • Dr. Benny Bruton [] USDA-ARS, Lane, Oklahoma, discussed the situation with watermelon germplasm at Griffin, Georgia. A preliminary report was handed out at the meeting. The final report was sent out in June. If you did not get a copy, we will have it on our Watermelon Research and Development Working Group Web Site, which is in the process of being moved to the Lane Research Station in Lane, Oklahoma. The new Web Site should be up and running by September, 1999. The address will be: [19th Annual Meeting]
  • Another topic that was discussed is a seed source for the watermelon differentials for determining race of Fusarium oxysporum f. sp. niveum. Dr. Todd Wehner agreed to get the differential germplasm, test it for purity, and increase it for distribution. Germplasm can be hard to find and impossible to know the genetic purity. I hope that, in the future, we can find someone to produce the differentials and offer them for sale. [19th Annual Meeting]

II. News

  • National Watermelon Promotion Board (NWPB). Mr. William Watson, Executive Director [], was not able to attend due to prior commitments. William did provide the group with a film of research projects that have been supported by the NWPB as well as research proposals that have been funded for 1999. The board of directors voted to add two more projects and to continue two research projects begun last year.
  • A new project at the Lane Research Station, Lane, OK will investigate the content and health properties of lycopene, a powerful antioxidant in watermelon. USDA-ARS investigator Dr. Penelope Perkins -Veazie [] will lead a team of researchers from USDA, Oklahoma State University, and Texas A&M, who will determine yield, stability, and quality of lycopene from marketable fruit and from watermelons considered culls.
  • In another new project, a team of researchers from Oklahoma State University will set up a system to better collect and disseminate production-related research to watermelon industry members. Researchers see a need to regularly communicate and relay information to the watermelon industry about cultivar and pesticide evaluations, fertility rates, and cultural practices. The group hopes to develop a national information exchange group to establish a mechanism for distributing research results and information to all facets of the watermelon industry.
  • The Directors voted to expand the work of Purdue University plant pathologist Richard Latin, who has developed a weather-based system designed to reduce fungicide use without increasing the risk of serious disease outbreaks. The system is called MELCAST or Melon Disease Forcaster. Growers have relied upon MELCAST to provide temperature and moisture readings that enable them to spray at the most opportune time, thereby improving disease control while reducing fungicide costs.
  • The Board also voted to continue University of Florida research by plant pathologist Dr. Don Hopkins who is investigating how to marshal a plant’s natural defense system to control disease through chemicals known as plant defense activators. These activators have no direct toxic effect on pathogenic fungi or bacteria and are not classified as fungicides. Early findings indicate thes activators are effective in preventing the spread of bacterial fruit blotch in the greenhouse and would be effective in reducing the amount of fruit blotch in the field.
  • The NWPB has budgeted $50,000 annually through 2001 to support research that addresses the following five research priority areas: (1) Postharvest physiology/quality, (2) Gummy stem blight, including host resistance, epidemiology, and control, (3) Standardization of variety evaluations and data accumulation, (4) Removal and disposal of plastic mulch, and (5) Disease forecast systems.

III. New Business

  • It was decided at the Memphis Meeting that we should invite all interested people (national and international) to become involved with our group. Once we get the Web Site working we want to enter their personal data into the system. We will have a search engine so that a person can find an expert in watermelon culture, fertility, plastic mulch, postharvest problems, foliar diseases, or soilborne diseases, etc.
  • This information should provide a very nice service to research and extension personnel to find needed information. We do not intend to try to duplicate information that is covered on other Web Pages. Hopefully, we will have the system up and running before long.

IV. Upcoming Meetings

  • 20th Annual Watermelon Research and Development Working Group will be at 1:00 to 5:00 PM on Sunday 30 January, 2000 in Lexington, Kentucky.
  • VIIth Eucarpia Meeting on Cucurbit Genetics and Breeding, 19-23 March, 2000 in Israel.

V. Special Thanks

  • I would like to extend a special thanks to Dr. Tom Williams of Novartis Seeds Inc. for sponsoring refreshments at this year’s annual meeting. We appreciate your support!

VI. Past Refreshment Sponsorships

  • Novartis Seeds Inc.: Memphis, Tennessee - 1999
  • Sunseeds: Little Rock, Arkansas - 1998
  • Barham Seeds: Birmingham, Alabama - 1997
  • American SunMelon: Greensboro, North Carolina - 1996
  • Willhite Seeds: New Orleans, Louisiana - 1995
  • Asgrow Seed Company: Nashville, Tennessee - 1994
  • American SunMelon:Tulsa, Oklahoma - 1993


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Page citation: Wehner, T.C., Cucurbit Genetics Cooperative;
Created by T.C. Wehner and T. Ng, 1 June 2005; design by C.T. Glenn;
send questions to T.C. Wehner; last revised on 19 February, 2008