Methods
Contains data taken at the Southern Regional PI Station. The data in this study was recorded by the staff of the Southern Regional Plant Introduction Station in Griffin, GA. For additional information, contact Robert Jarret at (404) 228-7207.
1998 Watermelon increase in Byron
1999 Watermelon increase in Byron
2000 Watermelon increase in Byron
2001 Watermelon increase in Byron
2002 Watermelon increase in Byron
1996 Watermelon increase in Byron
Evaluation of watermelon for resistance to Anthracnose Race 1 in Field Environment
Evaluation of watermelon for resistance to Anthracnose Race 1 in Growth Chamber
Evaluation of watermelon for resistance to Anthracnose Race 1 in Greenhouse
Evaluation of watermelon for resistance to Anthracnose Race 2 in Greenhouse
Evaluation of watermelon for resistance to bacterial fruit blotch, Acidovorax avenae subsp. citrulli. An isolate obtained in 1989 (WFB89-1) from a commercial watermelon variety was the primary isolate used in the greenhouse screening tests. The commercial watermelon 'Charleston Gray' was used as a susceptible check in all of the greenhouse screening tests.
Evaluation of watermelon for resistance to bacterial fruit blotch, Acidovorax avenae subsp. citrulli. An isolate obtained in 1989 (WFB89-1) from a commercial watermelon variety was the primary isolate used in the greenhouse screening tests. The commercial watermelon 'Charleston Gray' was used as a susceptible check in all of the greenhouse screening tests. Screening tests conducted during summer of 1997 and repeated during the winter of 1997-98.
3-yr study conducted a screening of 1,452 Citrulus spp. cultigens (PIs and cultivars) for resistance to BFB at the immature fruit stage.
2004 Citrullus and Praecitrullus increase in Byron, Georgia
2003 Watermelon increase in Experiment
2004 Watermelon increase in Experiment
Watermelon evaluated for fatty acid content using gas chromatography (GC) analysis
Evaluation of watermelon for resistance to Fusarium Race 1
Accessions of watermelon were tested for Gummy stem blight (GSB) resistance. GSB is caused by
Didymella bryoniae (Auersw.) Rehm [=
Mycosphaerella citrullina (C.O.Sm.) Gross. and
Mycosphaerella melonis (Pass) Chiu & Walker]. The resistant check was PI 189225 and the susceptible check was 'Charleston Gray'. Field and greenhouse studies were conducted from 1998-2001.
The most resistant cultigens were chosen as having a low mean disease severity rating (x<4.0) and a low standard deviation. The most susceptible cultigens were chosen as having a high mean disease severity rating (x>6.0) and a low standard deviation. PI 189225 and PI 271778 were previously reported sources of resistance (Sowell and Pointer, Plant Disease Reporter 46:883-885. 1962. 59:413-415. 1975). Cultigens more resistant than PI 189225 and PI 271778 both in the field and greenhouse tests under heavy artificial inoculation were assumed to be more adapted to survive natural epidemics of gummy stem blight. Therefore, data are presented for mean disease resistance for all accessions more resistant than PI 189225 (mean = 3.8, standard deviation = 1.2), the most resistant accession previously known. Including PI 189225, there were 60 accessions that had some level of resistance. PI 279461, PI 482379, PI 254744, PI 526233, PI 482276, PI 271771, PI 164248, PI 244019, PI 296332, and PI 490383 were selected as the most resistant cultigens.
View the disease assessment scale in an Excel Spreadsheet or as an HTML webpage. View summary statistics in an Excel Spreadsheet or as an HTML webpage.
Image of greenhouse and field grown fruit in Lane, Oklahoma or College Station, Texas
Images of watermelon submitted by various cooperators
Scanned Seed images of watermelon from Plant Genetic Resources Conservation Unit, Griffin, Georgia
2008 Watermelon increase at Isabela, Puerto Rico
2010 Watermelon increase at Isabela, Puerto Rico
Reported in literature or correspondence
2009 Watermelon increase at Mayaguez, Puerto Rico
Watermelon accessions in the CuCAP Molecular Core Collection
Watermelon accessions were tested against a race 2
Sphaerotheca fuliginea (Schlechtend.: Fr.) Pollacci isolate to evaluate for resistance to powdery mildew disease. Growth room-grown seedlings were artifically inoculated with conidia from watermelon host leaves at 2-day intervals from the appearance of the first true leaf until test results were taken, when the second true leaf was fully expanded.
Plants were evaluated on a 1 to 9 scale of increasing disease severity where 1 = no evidence of infection, 2 = trace infection of cotyledons only, 3 = low infection of cotyledons only, 4 = moderate infection of cotyledons only, trace infection of leaves, or no infection of cotyledons, slight infection of leaves, 5 = severe infection of cotyledons, slight infection of leaves, 6 = severe infection of cotyledons, moderate leaf infection as evidenced by leaf deformity and or sporulation on leaves, 7 = severe infection with abundant sporulation on cotyledons and leaves, or on leaves only, 8 = severe infection of leaves with some necrosis of leaves, and 9 = plant dead due to powdery mildew.
Disease indices (DIs) were calculated as a weighted average for each of these entries. Plants having powdery mildew ratings of 1.0 to 3.0 were classed as resistant, 3.1 to 6.0 were classed as intermediate resistance, and 6.1 to 9.0 were classed as susceptible.
All accessions of
Citrullus colocynthis and
Citrullus lanatus var.
citroides, and about 10% of
C. lanatus var.
lanatus (156) accessions from the U.S. Plant Introduction (PI) Citrullus germplasm collection were evaluated for resistance to root-knot nematode (
Meloidogyne arenaria race 1) in greenhouse tests.
Meloidogyne arenaria race 1 was cultured on 'Rutgers' tomato and 'Kentucky Wonder 191' pole bean in isolated soil benches in the greenhouse. Seeds of each accession were sown in the greenhouse in plastic growing trays and ten days later an aliquot containing approximately 2,500 eggs of
M. arenaria race 1 was pipetted into the soil surrounding each root system. Eight weeks after inoculation, the plants were severed at the crown and the roots were washed and immersed in a 15% solution of red food color to stain the egg masses. After rinsing gently under running tap water, they were evaluated for galling severity and egg mass production using a 1 to 9 scale.
View the disease assessment scale in an Excel Spreadsheet or as an HTML webpage.
The primary criterion for designating resistance and susceptibility of the accessions was the root gall severity index. Egg mass data was also presented because it provides additional information about the reaction of the accessions to Meloidogyne arenaria race 1. However, accessions were considered resistant only if both the root gall index and the egg mass index were <= 4.9. 'Charleston Gray', 'Crimson Sweet', and 'Dixie Lee' were included as susceptible check cultivars in all tests. Only one C. lanatus var. lanatus accession, PI 459074, could be classified as low resistance [root gall index (GI) = 4.9 and egg mass index (EMI) = 3.10]. All C. colocynthis accessions were highly susceptible (GI range = 8.5 to 9.0 and EMI range = 5.00 to 9.00). Twenty C. lanatus var. citroides accessions appeared moderately resistant with a GI = 3.1 to 4.0, but none were highly resistant.
Watermelon evaluated for seed oil content using time domain NMR (TD-NMR)
Watermelon evaluated for percent of total seed weight attributable to embryo and seed coat
2006 Watermelon increase in St. Croix