Watermelon Research and Development Group

Report from 1995 Annual Meeting

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15th ANNUAL MEETING, New Orleans, Louisiana
Sunday, January 29, 1995

• Ray D. Martyn, WRG Chair
• Texas A&M University, College Station, TX

The Watermelon Research Group met in New Orleans on Sunday, January 29, 1995, in conjunction with the Southern Association of Agricultural Scientists (SAAS) and the Southern Region of the American Society for Horticultural Science (SR:ASHS). Twenty five people were in attendance.

Don Maynard (UF-AREC, Bradenton, FL) presented an account of his and Gary Elmstrom's trip to Japan for the International Watermelon Summit in July, 1994. He indicated that a world library has been established and there was a world collection of watermelon germplasm on display. The price of melons in Japan was astounding. Watermelons were as much as $1.40/lb or $40-50 apiece. Cantaloupes ranged from $50-75 apiece.

Don Hopkins (UF-AREC, Leesburg, FL) presented an update on the watermelon fruit blotch (FB) disease. He indicated that there was a cooperative effort between seed corporations, research personnel, and transplant operations to solve this problem. Recommendations for growing melons for seed production are to grow in dry climates and where FB does not occur. Seed infection can be as high as 50% in some cases. The fruit does not have to show symptoms in order for the seed to be infected. The best seed treatment was 24-72 hr fermentation in 1% HCl, but this reduced the germination slightly to 85-90%. Greenhouse spread in transplants is favored by overhead irrigation and high humidity (>70%). Spread is very much limited below 50% RH. Spread of FB in the field is enhanced by rain events and overhead irrigation and is higher in spring crops than in fall crops. The wild citron was susceptible to FB in the laboratory; however, infected citrons have not found in the field. Don also reported that copper resistance has been detected in some isolates of the FB bacterium. Southern states with confirmed reports of fruit blotch include Florida, Louisiana, Georgia, South Carolina, and Texas.

Tom Garrett (Pee Dee-REC, Florence, SC) reported on FB trials in 24 triploid lines. The diploid pollinator had 90% fruit infection while the triploid fruit range from 10-30%. He indicated that the FB bacterium can persist in seed for at least 5 years. Marty Baker (TAES, Overton, TX) reported on a 4-year seedless watermelon variety trial in which over 25 varieties were evaluated. He reported that FB was not seen in any of the lines. He recommended a reduced spacing (6-8') for triploids with one row of pollinator for three rows of triploids with two active bee hives per acre. The size of the fruit continued to increase with most averaging 18-20 lbs currently. He is trying to develop a 22-28 lb triploid melon.

Frank Dainello (TAES, College Station, TX) reported on the progress of the fusarium wilt screening nursery being established in east Texas (Overton). They are still in the process of building up uniform inoculum of FON race I and race 2 throughout the fields. Commercial testing of lines is still 1-2 years away.

Charlie Johnson (LSU, Calhoun, LA) reported on his progress in developing a watermelon with resistance to FON race 2. Several lines look very promising. Joe Norton (Auburn, AL) reported on his screening program for ZYMV and the fusarium wilt resistance in Au-Producer. Dan Egel (American Sun Melon) gave an update on the gummy stem (Didymella bryoniae) research grant. Research is concentrating on the epidemiology and infection process and the development of a PCR seed detection method.

The next meeting of the Watermelon Research Group will be in Greensboro, NC on Sunday (1:00 PM - 4:00 PM), February 4, 1996, in conjunction with SAAS and SR:ASHS. For more information, contact Ray Martyn at 409-845-7311 (voice), 409-845-6483 (fax), or martyn@ppserver.tamu.edu (e-mail).