July 1993 Circular 311 Auburn University Agricultural Experiment Station Alabama Auburn University, Alabama Lowell T. Frobish, Director

AU-Sweet

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Scarlet
A Disease Resistant High Quality Watermelon with Dark Red Flesh

CONTENTS
Variety Development.................... Origin and Breeding History............... Disease Resistance...................... Fruit Characteristics..................... Summary............................ . Pest Control............ ............. Availability of Seed ..................... Acknowledgements...................... Literature Cited......................... Appendix............................. Page 4 . 4
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First Printing 3M, July 1993

Information contained herein is available to all persons without regard to race, color, sex, or national origin.

AU-SWEET SCARLET: A DISEASE RESISTANT HIGH

QUALITY WATERMELON WITH DARK RED FLESH
J.D. NORTON, G.E. BOYHAN, D.A. SMITH,AND BR. ABRAHAMS

AU-SWEET SCARLET is a multiple disease-resistant watermelon (Citaullus lanatus [Thumb] Matsum of Nakai) variety adapted to growing conditions in the southeastern United States. It has resistance to race 2 anthracnose (Colletotrichum obiculare [Berk and Mont.] Ark.) fusarium wilt (Fusarium oxysporium [f. sp. niveum (E.F.Sm.) Snyd. and Hans.]), gummy stem blight (Didymella bryoniae [Auersw. Rhem]). Disease is a major factor limiting production of watermelon in the southeastern United States. Anthracnose, fusarium wilt, and gummy stem blight are three of the most serious diseases. Severe crop losses and reduced yields of melons have resulted from these diseases in certain fields in Alabama. Although the damage seems to be more widespread in the Gulf Coast area, there have been frequent reports of damage in Central and North Alabama. Although satisfactory control of anthracnose and gummy stem blight may be accomplished with the proper application of fungicides during normal weather conditions, no control measure is effective during periods of high humidity and excessive rainfall. Furthermore, the three leading varieties, Charleston Gray, Jubilee, and Crimson Sweet are not resistant to race 2 anthracnose or gummy stem blight (1,2). The only practical control now available for fusarium wilt is varieties that are inherently resistant to the pathogen.

'Professor, Research Associate, Former Associate Professor, and Technician of Horticulture.

VARIETY DEVELOPMENT
The discovery that certain plant introductions (PI 189225 and PI 271778) were resistant to race 2 anthracnose (8) and gummy stem blight (6,7) led to the initiation of an Alabama Agricultural Experiment Station watermelon breeding program to develop multiple disease-resistant breeding lines that produce high yields of excellent quality fruit. Two of these lines AU-1 and AU-3, were released as AU-Jubilant and AU-Producer, respectively (4). The AW-1001CSY breeding line was released as AU-Golden Producer (3). AW-82-50CS was released as AU-Sweet Scarlet (3).

ORIGIN AND BREEDING HISTORY
AU-Sweet Scarlet was developed by the Department of Horticulture, and the Alabama Agricultural Experiment Station, Auburn University. It has multiple disease resistance to race 2 anthracnose, downy mildew, fusarium wilt, and gummy stem blight, as shown in Table 1. Crosses, backcrosses, and selfs were utilized, originating with the crosses Crimson Sweet x PI 189225, All Sweet x PI 362515, and Calhoun Gray x W.R. Peacock as shown in the pedigree, in the Figure 1. Resistance to gummy stem blight and race 2 anthracnose was incorporated into the breeding lines from plant introductions by a backcross program. Progeny were selected in a screening program that utilized an incubation chamber and greenhouse to eliminate susceptible plants from the population (1,3,4,5,6,7,8). Multiple disease resistance of AU-Sweet Scarlet has been excellent in field plantings.

TABLE 1. DISEASE INDEX RATINGS FOR RESISTANCE TO ANTHRACNOSE,
FUSARIUM WILT, AND GUMMY STEM BLIGHT

Disease index' Cultivar Anthracnose race 2 Fusarium wilt 3c 2b 3c Gummy stem blight 5b 5b 5b 2a 2a 2a

Charleston Gray .................. 5b Crimson Sweet ..................... 5b Jubilee ................................... 5b AU-Producer ....................... 2a AU-Golden Producer ......... 2a AU-Sweet Scarlet ................ 2a

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'Disease index: 0 = no injury, 1 = 1-20%, 2 = 21-40%, 3 = 41-60%, 4 = 61-80%, and 5 = 81-100% diseased plants. 2 Mean separation within columns by Duncan's multiple Range Test, 5% level.

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Crimson Sweet
Crimson Sweet

PI 189225

F1

F2

F3

Selfed 1981 All Sweet

Selfed 1982

Bulked 1984

F -F 1985-1990 AW-82-50-CS

PI 362515

Calhoun Gray

W.R. Peacock
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Pedigree of 'AU-Sweet Scarlet' watermelon.

Selections were made annually of disease resistant seedlings and high yield of excellent quality fruit. Resistance to gummy stem blight and race 2 anthracnose was secured from PI 189225 and PI 362515. Resistance to fusarium wilt was obtained from Crimson Sweet, All Sweet, Calhoun Gray, W.R. Peacock, and the plant introductions. AU-Sweet Scarlet has been grown as AW-82-50CS in trials at the E.V. Smith Research Center in Shorter and statewide at a number of Alabama Agricultural Experiment Station research sites. It also has been grown in Southern Cooperative Watermelon Trials in other Southern states, and in demonstration plantings by commercial growers.

DISEASE RESISTANCE
AU-Sweet Scarlet is resistant to downy mildew, race 2 anthracnose, and fusarium wilt, as shown in Table 1. Resistance to gummy stem blight, and race 2 anthracnose are significantly higher in AU-Sweet Scarlet than for Crimson Sweet and the other varieties. AU-Sweet Scarlet was developed from a program of backcrossing and inbreeding to obtain resistance to anthracnose, downy mildew, fusarium wilt, and gummy stem blight. Crosses, backcrosses, and selfs were utilized, originating with the crosses Crimson Sweet x PI 189225, All Sweet x PI 362515, and Calhoun Gray x W.R. Peacock as shown in the pedigree, in Figure 1. Following the crosses, a backcrossing and disease screening program was followed with selection for disease resistant seedlings and high yield of excellent quality fruit. Results of laboratory, greenhouse and field tests are given in Tables 1 and 2 and Appendix Tables 1, 2, and 3. FRUIT CHARACTERISTICS AU-Sweet Scarlet was found to be superior to Charleston Gray, Crimson Sweet, and Jubilee in quality, and disease resistance, as shown in Tables 1 and 2 and Appendix Tables 1 and 2. Yield of fruit was comparable to that of Charleston Gray, Crimson Sweet, and Jubilee, as shown in Table 2 and Appendix Tables 1 and 2. Fruit weight compares favorably with other varieties. Rind firmness was higher for AU-Sweet Scarlet than for Crimson Sweet, Jubilee, and AU-Producer, as shown in Table 8. A darker flesh color (46A 2) was observed for AU-Sweet Scarlet than for AU-Producer (46B 2) and Crimson Sweet (46C 2). Taste tests indicated that the edible quality (color, texture and taste) was higher in AU-Sweet Scarlet than Charleston Gray, Crimson Sweet, Jubilee

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RHS Colour Chart, The Royal Horticultural Society, London.

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Table 2. Yield and Fruit Characteristics of Varieties of Watermelons, Four Alabama Locations, 1988-1991 Variety Yield/ acre Fruit weight Soluble solids' Quality preference 2 Width/ length ratio Rind thickness Rind firmness 3 Days to maturity Rind color

Lb. Crimson Sweet ................... Jubilee ................................. AU-Producer ....................... AU-Golden Producer ........... AU-Sweet Scarlet ............... 22,481 16,594 22,513 20,173 19,120

Lb. 18.0 21.3 19.0 18.8 19.3

Pct. 10.4 9.6 10.8 10.8 11.4 8.0 7.9 8.2 8.2 9.0 .71 .45 .85 .85 .87

In. .86 1.00 .75 .75 .50 20.0 19.1 25.0 22.7 23.6 75 90 75 75 75 Green Green Green Green Green striped striped striped striped striped

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'Total soluble solids determined with Bausch and Lomb refractory, 0-25 percent scale. Response index: 9-10 = excellent, 7-8 = good, 5-6 = acceptable, and below 5 = unacceptable. Puncture test performed with Instron 1122 Instrument, 1-cm 2 Magnus Taylor probe. Puncture made at 5-cm intervals beginning at stem end.

and AU-Producer (Appendix Table 3). Mean total soluble solids of AU-Sweet Scarlet flesh was higher than for the other cultivars (Table 2 and Appendix Table 2). The fruit of AU-Sweet Scarlet are round to oblong-round in shape with few culls. Melons are similar to AU-Producer in size. Sizes are mostly in the 19.8-30.9 lb range but weights of 35 lb. are not uncommon. The rind color is light green with dark green stripes. The flesh is bright red (46A 2), firm but not tough. Rind and flesh characteristics make the melons well-adapted to shipping.

SUMMARY
AU-Sweet Scarlet is superior to the current varieties in quality and disease resistance and satisfactory in yield. AU-Sweet Scarlet is multiple disease resistant, with resistance to anthracnose, fusarium wilt, and gummy stem blight. The variety is being released to broaden the base of high quality, disease resistant melons available to growers in the southern United States. This high quality fruit with intense bright red color should be accepted in commercial markets, roadside markets, and for home gardens. Because of AU-Sweet Scarlet's early maturity, it fits well into the commercial production program to lengthen the season for any given production area or grower.

PEST CONTROL
Successful multiple disease resistance is essential for melon production, however, good grower production practices are also important in the control of insects, diseases, and nematodes. Rotation of crops, sanitation, and destruction of weed hosts will greatly reduce pest problems. In addition, a spray schedule may be necessary to control insects and diseases, particularly during periods of high humidity and rainfall.

AVAILABILITY OF SEED
An exclusive release of AU-Sweet Scarlet was made to Hollar and Company, Inc., Rocky Ford, Colorado 81067, for production and marketing of seed. Growers and home gardeners can find high quality seed at wholesale and retail outlets.

ACKNOWLEDGEMENTS
We gratefully acknowledge the assistance of J.S. Bannon and W.T. Hogue, E.V. Smith Research Center, Shorter, AL; J.A. Pitts and K.C. Short, Chilton Area Horticulture Substation, Clanton, AL; M.H. Hollingsworth, North Alabama Horticulture Substation, Cullman, AL; J.T. Eason and M.E. Ruf, Sand Mountain Substation, Crossville, AL; E.L. Carden and N.R. McDaniel,

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Gulf Coast Substation, Fairhope, AL; and H.E. Ivey and Larry Wells, Wiregrass Substation, Headland, AL; in increasing seed and conducting cultivar and breeding line trials.

LITERATURE CITED
(1)
(2)

NORTON, J.D. 1979. Inheritance of Resistance to Gummy Stem Blight in Watermelon. J. Amer. Soc. Hort. Sci. 14:630-632.
, J.M. SNELL, H.M. BRYCE, C.C. CARLTON, AND M.H.

HOLLINGSWORTH. 1983. Breeding Watermelons for Disease Resistance. Al. Agr. Exp. Sta. Highlights of Agr. Res. 30(4):2.
(3) , G.E. BOYHAN, B.R. ABRAHAMS, J.S. BANNON, J.A. PITTS,

(4) (5)

(6) (7)
(8)

(9)

M.H. HOLLINGSWORTH AND J.T. EASON. 1991. New Disease Resistant Watermelons Produced in AAES Research, Al. Agr. Exp. Sta. Highlights of Agr. Res. Vol. 38(4):8. , R.D. COSPER, D.A. SMITH AND K.S. RYMAL. 1986. AUJubilant and AU-Producer Watermelons. HortScience 21:1460:1461. , R.D. COSPER, D.A. SMITH AND K.S. RYMAL. 1983. AUJubilant and AU-Producer: Quality, Disease-Resistant Watermelon Varieties for the South. Al. Agr. Exp. Sta. Cir. 280. SOWELL, G.B., JR. AND G.R. POINTER. 1962. Gummy Stem Blight Resistance of Introduced Watermelons. Plant Dis. Rptr. 46:883-885. . 1975. An Additional Source of Resistance to Gummy Stem Blight in Watermelon. Plant Dis. Rptr. 59:413-415. , B.B. RHODES, AND J.D. NORTON. 1980. New Sources of Resistance to Watermelon Anthracnose. J. Amer. Soc. Hort. Sci. 105:197-199. SUVANPRAKORN, KAMOLVAN AND J.D. NORTON. 1980. Inheritance of Resistance to Race 2 Anthracnose in Watermelon. J. Amer. Soc. Hort. Sci. 105:862-865.

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APPENDIX

APPENDIX TABLE 1. AVERAGE YIELD PER ACRE OF WATERMELON VARIETIES AT FOUR LOCATIONS IN ALABAMA, 1991-1992

Variety

Clanton Lb.

Culiman Lb. 23,213 17,963 22,057 18,094 17,407

Fairhope Lb. 15,164 14,483 17,252 13,412 16,870

Headland Lb. 23,045 15,018 21,998 24,869 17,330

Crimson Sweet........................ Jubilee ................................. AU-Producer.......................... AU-Golden Producer ................ AU-Sweet Scarlet ....................

28,502 18,910 28,746 24,318 24,875

APPENDIX TABLE 2. YIELD, FRUIT WEIGHT, AND SOLUBLE SOLIDS OF WATERMELON CULTIVARS IN SOUTHERN COOPERATIVE WATERMELON TRIAL, 1989-1990

Cultivar

Yield/ acre Lb.

Fruit weight Lb. 8.7 9.7 8.8

Soluble solids
Pct.

Charleston Gray .................... Jubilee................................ AU-Sweet Scarlet...................

42,392 35,542 35,460

10.5 10.1 11.4

APPENDIX TABLE 3.

RESPONSE OF TASTE PANEL TO QUALITY OF WATERMELON

CULTIVARS AND BREEDING LINES, AUBURN, AL, 1988'

Cultivar or breeding line Charleston Gray..................................... Jubilee ....... ......................................... Crimson Sweet ...................................... AU-Producer......................................... AU-Sweet Scarlet .................................. 'Response index: 9-10
=

Color 7.5' 7.6 7.8 7.8

Texture 7.8' 7.9 8.0 8.1 9.0

Flavor 7.1 7.3 8.0 8.4 9.0
=

Average 7.5' 7.6 7.9 8.1 9.0 unacceptable.

9.0
=

excellent, 7-8

=

good, 5-6

acceptable, below 5

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APPENDIX TABLE 4.

FLESH COLOR OF WATERMELON CULTIVARS AND

BREEDING LINES, AUBURN, AL, 1988'

Hearts

Subseed

Cultivar or breeding line L Charleston Gray ....................... Jubilee ....................................... Crimson Sweet ........................... AU-Producer .............................. AU-Sweet Scarlet ...................... 39.10 41.77 38.27 43.55 44.62 a 30.95 29.46 28.58 31.05 31.25 b 15.25 15.15 14.60 15.33 15.40 L 38.84 38.84 38.19 39.92 40.54 a 27.17 27.17 23.97 29.75 30.45 b 14.73 14.73 14.60 14.73 16.86

'Hunter color difference values standardized to red plaque; L = 68.7, a = 23.0, and b = 9.4
where L = total light reflectance, a = red, and b = yellow.

APPENDIX TABLE 5.

RIND FIRMNESS (PUNCTURE TEST) OF WATERMELON CULTIVARS AND BREEDING LINES, AUBURN, AL, 1988'

Top side Cultivar Stem end Kg2 Charleston Gray ............ Jubilee ......... Crimson Sweet ........... AU-Producer AU-Sweet Scarlet .......... Kg Middle Blosssom end Kg Stem end Kg

Ground side Middle Blossom end Kg 15.7 11.6 Avg.

Kg 25.4 21.5

Kg 23.25 19.10

27.8 23.4

26.9 22.6

17.0 12.5

26.7 22.8

24.6 27.4

23.5 26.5

13.7 15.5

23.4 26.3

22.6 25.2

12.3 15.1

20.02 22.67

28.2

27.4

16.1

27.6

26.5

15.8

23.60

'Puncture test performed with Instron 1122 Instrument, 1 cm Magnus Taylor probe. Puncture made at 5 cm intervals at stem end. 2 One Kg equals 2.2 lb.

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Alabama's Agricultural Experiment Station System AUBURN UNIVERSITY

Wiith an agricu Itur'Al rese'archi unit in everx major soil area. AUburn Universitxserves4 the needs ol'I field5
crop, liv estock, forestry, anid horticultural producers in each region in Alabama. Every citizen of the state has at stake in

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tiiis research prograii.
si nce any adv antae from new~ and miore ol economical ws produc ing and handling tarmi piodlucts directlx benefits the cotnsumng public.

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*Main Agricultural Experiment Station, Auburn. E. V. Smith Research Center, Shorter.
Tennessee Valley Substation, Belle Mina. Sand Mountain Substation Crossve.e North Alabama Horticulture Substation. Cullman. Upper Coastal Plain Substation. Winfield. Forestry Unit. Fayette County. Cnilton Area Horticulture Sobstation. Clanton. Forestry Unit. Coosa County. Piedmont Suostation. Camp H il Foresty Unit. Autauga County. Prattv ile Experiment Feld Prattville. 11t Black Belt Substation. Marion Junction. 12. The Tu~rnipseed-Ikerberry Place. Union Springs. 13. Lower Coastal Plair Suostation. Camden. 14. Forestry Unit. Barboir County 15 Monroesille Experiment Field. Monroev ille. 16. Wiregrass Substation. Headlano. 17 Brewtoni Experiment Pield Brewton. 18 Ornamentai Horticulture Substation. Spring Hili. 19 guClf Coast Substation. Fairhope.