7 pp., 2 figures, 5 tablesThis profile of watermelon production in Texas gives an overview of basic commodity information; discusses insect, disease and weed pests; cultural and chemical control methods

Hall, Kent D.

Holloway, Rodney L.

Smith, Dudley

Texas A&amp;M Repository

This profile on watermelon production in Texas gives an overview of basic com-modity information; and discusses insect, disease and weed pests, cultural andchemical control methods.Basic Commodity Information—1996-98 AverageState Rank: ..........................Texas is the nation’s number one producer of commercial watermelons.Percent U.S. Production: 20 percentAcres Planted: ......................50,000 to 60,000 Cash Value: ..........................Cash receipts total approximately $50 million. Inaddition, an unknown quantity of melons are sold out of small roadside stands and from the back of trucks along the roadside by people who do not ship melons. Watermelons, along with a number of other vegetable crops, are an important source of supplemental income in many areas of Texas.Yearly Production Costs:Total fertilizer ..........................$32.00 per acre, nitrogen applied at 40pounds per acre; phosphate applied at 60 pounds per acre Seeding rate ..............................3 pounds per acre at $20 per poundTotal pesticide ..........................$110 per acre; herbicides, $51 per acre; insecticides, $23 per acre; fungicides, $32 per acre; application cost, $4.00 per acrePollination ................................$30 per acreHarvest expense........................$3.50 per acrePlastic mulch ............................$75 to $275 per acre depending upon plasticusedMachinery labor cost ................$18 per acre Other labor cost ........................$65 per acreVariable costs (South Texas) ....irrigated, $1071.94 (drip tape approximately$225 per acre); dryland, $748.94 per acreFixed costs (South Texas) ........irrigated, $151.55 per acre; dryland, $78.42per acreCommodity DestinationOne hundred (100) percent of the state’s watermelon production goes to thefresh market.Production RegionsWatermelons are grown in nearly half the counties in Texas. The top fivewatermelon producing counties are Hidalgo, Brooks, Knox, Gaines and Wood. TheTexasCropProfileWATERMELONSE-213-00Prepared by Rodney L. Holloway and Kent D. Hall1In collaboration with Frank Dainello, Lynn Brandenberger, James Robinson,George Philly, Mark Black, Noel Troxclair and Tom Isakiet21Extension Specialist and Extension Associate, The Texas A&M University System.2Extension Horticulturist, Extension Horticulturist, Extension Horticulturist, Extension Entomologist,Extension Plant Pathologist, Extension Entomologist and Extension Plant Pathologist, The TexasA&M University System.accompanying map shows different geographicalcropping areas in Texas. Watermelons are commer-cially grown in regions 1, 3, 4, 6 and 9.Watermelons are an annual crop in Texas.Harvest starts in early May in the Lower RioGrande Valley (South Texas), June in the WinterGarden, June-July in East Texas, late summer andearly fall in the Cross Timbers/DeLeon area, andin September and October in the High Plains.Eighty (80) percent of Texas production is market-ed in June, July and August. The optimum mar-keting window is mid June through mid July. Each of the Texas production regions will oftenhave unique pest problems. Diseases are a goodexample. Anthracnose and gummy stem blight areimportant problems in northern areas of the statebut are generally not considered to be conditionsworth treating in South Texas and the WinterGarden. Cultural PracticesVarieties: Hybrids - Royal Jubilee, Royal Sweet,Prince Charles, Summer Flavor 500, Sangria,Royal Sweet, Big Stripe, Fiesta. Open pollinated -All Sweet and Jubilee II. About 65 percent of theTexas commercial watermelon production ishybrid, 20 percent is open pollinated and 15 per-cent is seedless.Soil preference: Deep, well-drained, light tex-tured soil having a pH range of 5.5 to 8.0 (opti-mum 6.5 to 7.0) is preferred. Watermelons do nottolerate heavy soils. Optimum growing conditions: Bright, hotdays (80 to 95 degrees F) and warm nights (60 to70 degrees F) are optimum. Cooler temperaturesand excessive rainfall slow growth and maturity.Overcast, cloudy and or rainy weather reducessugars (fruit quality). In Texas, a 3-year rotation isrecommended for watermelons to reduce the inci-dence of fusarium.Establishment methods: Watermelons usuallyare direct seeded or transplanted, often on plasticmulch covered raised beds. Optimum planting timeis when all danger of frost has passed and/or soilseed zone temperature exceeds 70 degrees F.Seeding rate is 1 to 3 pounds per acre, 300 to 600seed per ounce. Plant seed at a depth of 3/4 inch to1 inch. Seeding spacing is equal to 3-foot in-row on6-foot beds (irrigated); 5-foot in-row on 8-foot to 10-foot beds (dry land).Fertilization: Actual fertilization rates must bebased on soil test results. General rate, in poundsper acre, is 80-80-80. Actual applications may varyas follows. Nitrogen - 40 to 90 pounds total; apply 0 to50 pounds preplant broadcast incorporated orsplit band 4 inches deep and 4 to 6 feet oneither side of seed row at planting plus 20 to30 pounds sidedressed 3 weeks after emer-gence. Under high rainfall, an additional 20pounds may be required at vining (sidedressis split bands or through fertigation).  Phosphorus - 40 to 80 pounds total; applybanded 3 to 4 inches below seed at plantingor near the level of the transplant root base.  Potassium - 40 to 80 pounds total; if neededapply with preplant nitrogen. Starter solutionfor transplants equals approximately 8ounces of high phosphate starter solution perplant at field setting.Irrigation: Between 10 inches to 15 inches ofwater per season is needed. A steady moisture sup-ply (1 inch to 2 inches every 10 to 14 days) isrequired. Stop irrigation approximately 10 to 14days prior to anticipated maturity (onset of fleshcolor). Key stages for irrigation are establishmentand fruit set.2Pest InformationInsectsKey pests are cucumber beetles, aphids andsquash bugs. Others include cutworms, cabbagelooper, leaf hoppers, leaf miners, melon worms,pickleworms, mites, squashvine borers and fleabeetles.AphidsAphids are often a mid to late season pest ofTexas watermelons. Damage results from theaphids’ honeydew secretions. Since most watermel-ons are taken directly from the field to market, thehoneydew, a sticky sweet substance, causes unde-sirable appearance for market. Aphids also maytransmit certain mosaic viruses that attack water-melons. Aphids feed on the underside of leaves,causing cupping and distortion. Warm humidweather coupled with vigorous well fertilized vinesare conducive for aphid development. Scouting isan effective management tool; five aphids per leafsignals a damaging population. Beneficial insectssuch as lady beetles and lacewings can reduceaphid numbers and limit the number of requiredinsecticide applications. Cucumber beetlesCucumber beetles are generally only a problemto young watermelon plants. When the crop is firstbecoming established, these beetles will feed onyoung tender stems, leaves and shoots. Once vinesare older and more dense, beetle damage can betolerated. Cucumber beetles are green oblong-ovalColeoptera that are about 5 mm long. Females layoval, orange-yellow eggs in clusters of 25 to 50 onthe undersides of host plant leaves. The beetle lar-vae are about 10 mm long and have a yellow-white, somewhat wrinkled body with three pairs ofbrownish legs near the head. Pupae are white,tinged with yellow and 6 to 8 mm long.Overwintering is in fence rows and surroundingfields. Squash bugsSquash bug adults and nymphs feed on plantstems and leaves, often near the base of the plant.Damage occurs when unusually large populationsare on the melons. Damaged leaves appear grayishand may wilt and die. Adults are brownish gray todark gray bugs about 5/8 inch long. Nymphs havea green abdomen with crimson head. Eggs are laidin clusters often on the top of leaves. Developingimmatures generally are found underneath.Squash bugs transmit anasa wilt to watermelons.Synthetic pyrethroid insecticides used for squashbug control can cause late season aphid populationincreases.White fliesWhite flies feed by sucking plant juices fromhost plants and heavy feeding can cause mottlingor yellowing of the leaves. Adult whiteflies areabout 1/16 inch long and have four wings alongeach side of the body that are covered with a whitewaxy powder. Immatures or nymphs are lightgreen, oval, and about the size of a pinhead. Whitefly adults secrete honeydew that often will turnblack and blemish fruit because honeydew is amedium for smutty mold.DiseasesGummy stem blightGummy stem blight (GSB) (Didymella bryoniae)is one of the most important diseases of Texaswatermelons. Expressed in warm wet weather (theoptimal temperature is 74 degrees F), symptomsinclude round, black, wrinkled spots on leaves andsunken dark areas on stems. A gummy brownmaterial will ooze from older stems in the laterstages of disease development. Disease develop-3Table 1: Chemicals for Watermelon Insect Control.*Chemical % Acres Treated Appl. per Year Pounds A.I. per Acre Primary TargetCarbaryl (Sevin®) 4 1.3 0.87 Cucumber beetleDiazinon (Diazinon®) 1 1.9 0.28 Cucumber beetleDimethoate (Cygon®, Defend®) 5 1.2 0.12 AphidEndosulfan (Thiodan®, Phaser®) 26 1.2 0.69 Squash bugEsfenvalerate (Asana®) 2 1.2 0.02 Squash bugImadicloprid (Admire®, Provado®, Gaucho®) 3 1 0.2 AphidMalathion (Malathion) 3 1.2 0.67 AphidMethomyl (Lannate) 14 2 0.42 Squash bug*56,000 acres in 1996.ment begins at the center of the plant and pro-gresses outward. On the fruit, lesions appear assmall water soaked areas that eventually enlargeto an indefinite size. This fungus overwinters ininfected plant debris in the soil and on seed.Cultural control suggestions include to not disturbvines that are wet from dew or rain.AnthracnoseAnthracnose (Colletotrich orbiculare) is a consis-tent watermelon disease in East Texas and occa-sionally a problem in the northeast. Anthracnosecan completely kill vines before fruit matures, andwill cause lesions on the fruit. The disease symp-toms include irregular, brown to black, dry leafspots that eventually cause the leaf to shrivel upand die. On the fruit, sunken, circular to irregularlesions occur from pinpoint size to 1 inch or morein diameter. Elongate stem and petiole lesionsoccur. Spores of the fungus produced on lesionsmay rapidly spread the infection following rainyweather. The fungus overwinters in decaying vinesand on seed from diseased fruit. Infected fruit areoften ruined in the field or lost to decay in transit.Powdery mildewTwo fungi, Spaerotheca fuliginea and Erysiphecichoracearum, are responsible for the powderymildew disease. These quickly spreading fungi firstappear as a white to gray dusty material on theupper leaf surface and subsequently spread tocover the entire surface. Once a leaf becomes cov-ered by powdery mildew it will become dry andbrittle, and eventually die. These diseases developon older leaves and tend not to be a consistentproblem in Texas melons. WiltWilt (Fusarium oxysporium) fungi are soil borneand enter the plants through the roots. Early dis-ease symptoms are a brown discoloration insideroots and stems that leads to plant vascular sys-tem breakdown. Plants wilt, then die soon aftersymptoms are observed. Foliage of infected plantsfirst turn yellow, signaling the presence of fusari-um. Crop rotation is the best control method andoften requires intervals as long a 5 years betweenplantings.Downy mildewThis disease first appears as large brown blotch-es on the upper surface of leaves and can rapidlydefoliate vines. Stems and fruit are not affected.Downy mildew (Pseudoperonospora cubenis) devel-opment is favored by cool, wet nights and warmhumid days. It is mainly important in late-season(fall) production possibly because it does not over-winter well but moves in from tropical areas. Thekey to effective chemical treatments are early dis-ease detection and regular preventative applica-tions. Cultural control includes planting resistantvarieties, isolating fields and reducing plant densi-ty to promote more open canopies.Cercospora leaf spotThis disease (Cercospora sp.) causes small leafspots that can cause defoliation of vines undersevere disease pressure. Airborne movement ofspores is important for introducing the pathogen.The irregular leaf spots have a yellow halo and adark brown center that first appear on the oldestleaves. Damage is from defoliation that can restrictfruit development and from increased exposure ofmelons to the sun, resulting in scalding.Cercospora leaf spot is the most prevalent foliardisease of watermelon in many parts of Texas butit is not usually a serious problem. However,because heavy infection can lead to defoliation,chemical control is often advised, particularly insouth Texas.Alternaria leaf blightThis fungus (Alternaria cucumerina) overwin-ters on plant debris from the previous crop. Thedisease manifestation is similar to cercospora;older leaves are affected first and then newerleaves, shoots and runners. Alternaria lesionsresemble a target with a lighter area encircling adark spot. A minimum of 2 years rotation is recom-mended as a cultural management practice for thisorganism. 4Cucumber beetleAzinphos-methyl     (Guthion®)Carbaryl (Sevin®)CryoliteDiazinon (Diazinon®)Endosulfan (Thiodan®)Esfenvalerate (Asana®)LindaneMalathianMethomyl (Lannate®)MethoxychlorPermethrin (Ambush®,    Pounce®)AphidsDiazinon (Diazinon)Dimethoate (Cygon)Endosulfan (Thiodan®)LindaneMalathionMethomyl (Lannate®)Oxamyl (Vydate®)Oxydemeton-methyl (Metasystox-R®)Permethrin (Ambush®, Pounce®)Squash bugCarbaryl (Sevin®)Endosulfan (Thiodan®)Esfenvalerate (Asana®)LindanePermethrin(Ambush®,    Pounce®)Table 2: Chemical Alternatives for Major WatermelonInsect Pests.5Angular Leaf SpotCopper & ZincAnthracnoseChlorothalonilFosetyl-aluminum & ManebMancozeb, ManebManebMefenoxam & ChlorothalonilBacterial Fruit BlotchMancozeb & CopperCucumber Belly RotChlorothalonilDowny MildewChlorothalonilCopper & ZincFosetyl-aluminumFosetyl-aluminum & ManebMancozeb & CopperMancozeb, ManebManebMefenoxam & ChlorothalonilMefenoxam & MancozebMetalaxyl & MancozebGummy Stem BlightChlorothalonilFosetyl-aluminum & ManebMancozeb & CopperMancozeb, ManebManebMefenoxam & ChlorothalonilLeaf SpotChlorothalonilFosetyl-aluminum & ManebMancozeb & CopperMancozeb, ManebManebMefenoxam & ChlorothalonilLeaf Spot/Leaf BlightChlorothalonilCopper & ZincFosetyl-aluminum & ManebMancozeb & CopperMancozeb, ManebMefenoxam & ChlorothalonilPlant Parasitic NematodesOxamylPowdery MildewCopper & ZincChlorothalonilCopper & ZincScabChlorothalonilCopper & ZincMancozeb, ManebMefenoxam & ChlorothalonilTarget SpotChlorothalonilTable 3: Watermelon Disease Control Chemicals.* Chemical Target Pests Pounds A.I. per Acre % Area Treated # of Appl. Benomyl (Benlate®) Powdery mildew, anthracnose, gummy stem blight 0.22 9 1.7Chlorothalonil (Bravo®) Cercospora leaf spot, anthracnose, downy mildew, gummy stem blight, alternaria leaf spot,powdery mildew 1.15 38 3.3Copper hydroxide 0.42 9 2.2 Mancozeb Cercospora leaf spot, anthracnose,  downy mildew,gummy stem blight, alternaria leaf spot 1.28 12 2.8 Metalaxyl Combined with maneb for downy mildew 0.12 11 2.3 Azoxystrobin (Quadris®) Gummy stem blight, powdery mildew, some activityagainst downy mildew 0.10-0.25 10 2.0 *Many fungicides are applied in combination with other fungicides to broaden an application’s spectrum of control.Table 4: Watermelon Disease Control Alternatives.Other watermelon maladiesOther diseases considered to be occasional pestsof Texas watermelons include white mold(Sclerotinia sclerotiorum), Rhizoctonia solani,damping off (Pythium) which is managed with seedtreatments, and bacterial fruit blotch (Acidivoraxavenae). The squash leaf curl virus, a common dis-ease of fall watermelons, is transmitted by white-flies and can be managed by controlling the white-flies. Other viruses include the watermelon mosaicvirus, papaya ringspot virus and the tobaccoringspot virus.Chemical control of watermelon diseases:There are several chemicals that are used for dis-ease control in watermelons. Most are efficaciousagainst more than one pest. This broad spectrumcharacteristic influences the use of a materialbecause a product usually becomes the chemical ofchoice if numerous diseases are controlled with asingle application. Use information is complicatedby the fact that many compounds are used in com-bination with other fungicides.Resistance management: Combination ofchemicals is often recommended to help preventdisease resistance. For instance, menfanoxam(Ridomil Gold) can be used in combination withprotectant fungicides such as mancozeb orchlorothalonil to help prevent the emergence ofresistant strains. Alternative chemical applicationsare suggested for new fungicides such as Quadristo prevent the development of disease resistance. 6Rodney L. HollowayExtension Specialist2488 TAMUCollege Station, Texas 77843-2488979-845-3849rholloway@tamu.eduKent HallExtension Associate2488 TAMUCollege Station, Texas 77843-2488kd-hall@tamu.eduFrank DainelloExtension Horticulturist2134 TAMUCollege Station, Texas 77843-2134979-845-8567f-dainello@tamu.eduLynn BrandenbergerExtension HorticulturistTAMU Weslaco Center2401 East Highway 83Weslaco, Texas 78596-8344956-968-5581l-brandenberger@tamu.eduMarvin MillerResearch HorticultureTAMU Weslaco Center2401 East Highway 83Weslaco, Texas 78596-8344m-miller@tamu.eduTable 5. Weed Control in Watermelons.*Chemical % Area Treated Appl. per Year Pounds A.I. per Acre CommentsEthalfluralin (Sonalan™) 7 1.0 0.58 Apply after seeding to the soil surface.Sethoxydim (Poast®) 6 1.3 0.18 Apply postemergence to young, actively growing grass.Trifluralin (Treflan™) 29 1.0 0.55 Apply postemergence, directed to the soil under crop leaves.*National Agricultural Statistics 1996: http://usda.mannlib.cornell.edu/reports/nassWeedsWeeds are a constant problem in Texas water-melons. Plastic mulch has become an importanttool in watermelon weed management and inwater conservation. Weed control is essential toprevent mulch damage. Annual broadleaf weeds,annual grasses and perennial grasses are the tar-gets of herbicide applications. Application timingand the understanding of weed life cycles areessential elements of successful control. Applica-tion timings are preplant or preemergence, earlypostemergence and postemergence (postdirected).State ContactsBrandenberger, Lynn. South Texas ValleyVegetable Notes. Texas A&M UniversityResearch and Extension Center at Weslaco.Vol. 5, No. 11,1997. 4 pp.E-10, “Vegetable and Herb Disease ControlProducts for Texas,” Texas Plant DiseaseHandbook. Texas Agricultural ExtensionService, http://agpublications.tamu.edu/pubs/eplant.“Texas Commercial Vegetable Production Guide.”Texas Agricultural Extension Service. B-1305, “Insect Control Guide for CommercialVegetables.”  Texas Agricultural ExtensionService.B-5022, “Weed Control in Vegetable, Fruit and NutCrops.” Texas Agricultural Extension Service.National Agricultural Pesticide Impact AssessmentProgram Web Sitehttp://ipmwww.ncsu.edu/opmppiap/.Texas A&M University Research and ExtensionCenter at Weslaco Web Sitehttp://primera.tamu.edu/.Texas Agricultural Statistics. 1997.USDA/National Agricultural Statistics Servicehttp://usda.mannlib.cornell.edu/reports/nass.ReferencesThe information given herein is for educational purposes only. Reference to trade names is made with the understanding that no dis-crimination is intended and no endorsement by the Texas Agricultural Extension Service is implied.

Texas Crop Profile: Watermelon

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Texas Crop Profile: Watermelon

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Texas Crop Profile: Watermelon

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