Crop Profile for Watermelons in Oklahoma

Prepared: March, 1999
Revised: June, 2003

General Production Information

Production Regions

The highest watermelon production levels are in the southwestern counties of Caddo and Jefferson. The following is a map showing counties that reported harvesting watermelon acres in 1997.



Cultural Practices

Watermelon planting begins in late March in southern Oklahoma and mid April in northern areas. Seed will not germinate at soil temperatures below 60o F. Seedling emergence usually occurs in seven to ten days if soil temperature at seed depth is 65 to 68o F. Some watermelons are transplanted and are generally grown on plastic mulch.

Shallow mechanical cultivation and hand hoeing are needed to control weeds before plants have vined. Pruning roots and vines with cultivating equipment slows melon development and reduces yield. Several pre-emergence herbicides are available that will control germinating broadleaf weeds and grasses in seeded and transplanted watermelons if used properly. Chemicals are economical when used as a band application over the planted row.

Worker Exposure Issues

Applicators: Oklahoma watermelons are regularly treated with insecticides, fungicides, and herbicides. In a 1993 survey 67% of watermelon acres were treated with fungicides, 85% of acres treated with herbicides, and 85% with insecticides. Insecticides were applied 76% by ground and 24% by air. Herbicides were applied 93% by ground and 7% by air. Fungicides were applied 65% by ground and 35% by air. Eighty two percent of the acres were treated by the farmers themselves and 18% were treated by commercial applicators.

Number of Applications: In 1993 an average of 1.3 applications per year of insecticides were used on Oklahoma watermelons. Fungicides were applied on average 1.5 times per year. Herbicide use is mostly pre-plant or post-emergence which accounts for one application per year. The only exception would be Poast which could be used more than 1 time.

Hand Labor and Harvesters: In 1993 71% of watermelon acres were hand hoed for weed control and more than one hoeing could occur. 35% of the acreage was cultivated and 15% was mulched. Watermelons are harvested, and packaged exclusively by hand in Oklahoma usually by seasonal migrant workers.



Insect Pests

Oklahoma watermelon producers report squash bugs (Anasa tristis), aphids, and cucumber beetle adults (Diabrotica undecimpunctata howardi) as their major insect problems.

1993 Insecticide Use Survey of Watermelon Growers

Insecticide

Total Acres Treated

Average Applications Per Year

Asana (esfenvalerate)

1905

 1.5 (1-3)

Bacillus Thuringiensis

10

1

Dimethoate (dimethoate)

190

1

Diazanon (diazanon)

45

2

Furadan (carbofuran)

2095

1

Kelthane (dicofol)

200

1

Lannate (methomyl)

1.5

1

Malathion (malathion)

38

1.3 (1-2)

Metasystox-R (oxydemeton-methyl)

25

1.5(1-2)

Permethrin

4.5

1.3 (1-2)

Phosdrin

200

1

Pyrethrins

10

1

Sevin (carbaryl)

254

1.6 (1-4)

Thiodan (endosulfan)

522

2 (1-3)


2003 Estimated Use by State Specialist

Insecticide

Total Acres Treated

% of Acres Treated

Average Applications Per Year

Asana (esfenvalerate)

1905

25

1.5 (1-3)

Bacillus Thuringiensis

10

1

1

Dimethoate (dimethoate)

190

25

1

Furadan (carbofuran)

2095

55

1

Kelthane (dicofol)

200

15

1

Lannate (methomyl)

1.5

10

1

Malathion (malathion)

38

1

1.3 (1-2)

Metasystox-R (oxydemeton-methyl)

25

50

1.5 (1-2)

Permethrin

4.5

10

1.3 (1-2)

Pyrethrins

10

1

1

Sevin (carbaryl)

254

15

1.6 (1-4)

Thiodan (endosulfan)

522

25

2 (1-3)

Actara (thiamethoxam)

140

2

1

Platinum (thiamethoxam)

140

2

1

Provado (imidacloprid)

350

5

1

Fulfill (pymetrozine)

70

1

1

Spintor (spinosad)

350

5

1

Capture (bifenthrin)

700

10

1

Danitol (fenpropathrin)

140

2

1

Agri-mek (abamectin)

1050

15

1


Insect Pest Occurrence

Cucurbit Integrated Crop Management

----------------------------------------------------- Crop Time Line --------------------------------------------------

Preplant Planting Seedling Vining Flowering Fruit Set Fruit Development Harvest Post-Harvest
soil insect pests --wireworms and grubs thrips, cucumber beetles, squash bugs, and cutworms cucumber beetles, squash bugs, aphids DO NOT APPLY INSECTICIDES cucumber beetles (larvae), squash bugs, aphids, mites, melonworms and pickleworms, squash vine borers


Striped and Spotted Cucumber Beetles
Acalymma vittata and Diabrotica undecimpunctata howardi

Both species of cucumber beetles are known to infest watermelon fields. Beetles over winter in nearby hedgerows and woodlands feeding on alternate weed hosts in the early spring. As soon as melons germinate in March and April, beetles migrate to the field and begin feeding on young seedlings. Although most watermelon cultivars have good bacterial wilt resistance, heavy beetle populations (greater than 5 per plant) can severely affect stand establishment during the cotyledon stage. Once the first three leaves are established, plants generally compensate for damage through vigorous growth. Cucumber beetle adults can be vectors for bacterial wilt. Cucumber beetle larvae have also been commonly reported damaging mature fruit by tunneling into the rinds at the fruit soil contact point. Because cucumbers beetles pose a big problem for Oklahoma Watermelon producers and the increase in triploid hybrid seedless watermelon production soil applications of Furadan have become an important tool for Oklahoma Watermelon producers.

Controls


Aphids
Aphis gossypii

Aphids feed mainly on the undersides of the leaves causing cupping of leaves, leaf distortion, plant stunting, and a reduction in the quality and quantity of fruit. Infestations are usually higher in hot, dry summers following cool springs which reduce the efficiency of natural enemies. In addition, over fertilization with nitrogen can increase aphid populations. Honeydew secreted by aphids supports growth of rooty mold on leaves and fruit. Aphids may transmit viruses.

Controls


Spider Mites
Tetranychus spp.

Spider mites can be a serious pest of watermelons, especially during hot, dry weather. Infested plants appear yellow and become visible from a distance. Mites are primarily found on the undersides of leaves making the leaves appear tan or yellow and have a "crusty appearance". Mites feed on the plant sap and can defoliate vines in a few weeks in hot, dry weather. Defoliated plants tend to yield small, poor quality fruit.

Controls


Squash Bugs
Anasa tristis

Squash bugs feed on plant pholem and xylem. Both adults and nymphs feed on plants. Squash bugs can occur in large numbers, weakening or killing plants. Damaged leaves appear grayish and may wilt and die. Adults tend to occur around the base of the plant near the ground, and may be abundant in fields with plastic mulch.

Controls

Successful management of squash bugs is based on prohibiting early season population increases.



Weeds

Oklahoma Watermelon producers report pigweed (Amaranthus spp.), crabgrass (Digitaria sanguinalis), and johnsongrass (Sorghum halpense) as the most troublesome weeds in watermelon production. Mustards, lambsquarter, morningglory, and panicum were also some of the other weeds identified by producers as weed problems.

1993 Weed Control Use Survey of Watermelon Growers

Herbicide

Total Acres Treated

Average Applications/yr

Alanap (naptalam)

340

1

Curbit (ethalfluralin)

471

1

Prefar (bensulide)

340

1

Poast (sethoxydim)

485

1

Treflan (trifluralin)

2540

1

Cultivation

1127

 ----

Mulches

101

 ----

Hand hoe

2289

 ----


2003 Estimate by State Specialist

Alanap (naptalam)

340

1

Curbit (ethalfluralin)

471

1

Prefar (bensulide)

Few

1

Poast (sethoxydim)

4000

1

Treflan (trifluralin)

5000

1

Strategy (ethalfluralin+ clomazone)

1000

1

Sandea (halosulfuron)

2000

1

Prism/Select (clethodim)

1000

1

Cultivation

10000

 ----

Hand hoe

3000

 ----

Weeds can cause losses to watermelon production in numerous ways. Weeds compete for nutrients, water and light causing a reducing in yield potential. Also, weed foliage may intercept the spray of fungicides and insecticides and prevent contact with watermelon foliage and fruit. Lastly, harvesting crews cannot find the watermelons covered by weeds and slows harvest.

Cultivations are an essential component of watermelon production. However, without herbicides it is increasingly difficult to cultivate watermelon fields. Herbicides are an aid to cultivation because they suppress weed growth until plants can become large enough for cultivation.

Herbicides provide weed control in a band down the row. This provides chemical weed control within the row without the cultivation which can retard plant growth. It also then allows the row row middles to be cultivated.

In 2002 two new products were labeled for watermelons in Oklahoma: Sandea (Halosulfuron) can be applied preemergence to direct seeded fields at a rate of 0.5 to 0.75 oz of material/acre. Currently the label will allow Sandea to be applied to row-middles only for transplants at 0.5 to 1.0 oz/acre rates. Sandea will control several broadleaf weeds and both yellow and purple nutsedge (postemergence).

Strategy (Curbit [ethalfluralin]) + Command 3ME [clomazone]) labeled for use in watermelon as a preemergence application at a rate of 2 to 6 pints/acre for the control of several grassy and broadleaf weeds.

Chemical Control

Emerged annual broadleaf weeds, grass

Gramoxone Max
(Paraquat)

Preplant or Preemergence

0.56 to 1.0 lb/acre

Apply to emerged weeds before crop plants emerge. Cannot be applied over crop.

Annual broadleaf weeds

Alanap L
(Naptalam)

Early Postemergence

2 to 4 lb/acre

Apply to a clean soil after transplanting and before weeds emerge.

Alanap L
(Naptalam)

Pre or Postemergence

3 to 4 lb/acre

Apply to a clean soil after transplanting and before weeds emerge.

Annual grasses

Prefar 4E
(Bensulide)

Preplant

5 to 6 lb/acre

Incorporate thoroughly into the soil with shallow cultivation or irrigation before planting.

Prefar 4E
(Bensulide)

Preemergence

5 to 6 lb/acre

Apply to flat-planted or bedded crops. Incorporate with irrigation.

Annual grass and broadleaf weeds

Alanap 2L +
Prefar 4E
(Naptalam + Bensulide)

Preplant

Alanap L – 2 to 4 lb/acre +
Prefar 4E – 4 to 6 lb/acre

Incorporate the mixture into the soil at a depth of ½ to 1 inch or use overhead irrigation.

Treflan
(Trifluralin)

Postemergence

0.5 to 1.0 lb/acre

Apply as directed spray under leaves when crop is in the 3 to 4 leaf stage and immediately into the soil.

Curbit
(Ethalfluralin)

Preemergence

See label

Use only as post-plant surface application immediately after seeding.

Emerged annual and perennial grasses

Poast
(Sethoxydim)

Postemergence

See label

Apply to young actively growing grass. Do not apply within 14 days of harvest.

Annual weeds, Johnsongrass, Bermudagrass

Roundup
(Glyphosate)

Preplant

See label

Apply prior to planting. Allow 3 days between application and planting.



Diseases

Anthracnose and powdery mildew are the two most common disease problems for Oklahoma Watermelon producers. Leafspot, downy mildew, gummy stem blight, and bacterial fruit blotch can be encountered by producers but normally do not represent the disease problems year after year that anthracnose and powdery mildew do.

1993 Fungicide Use Survey of Watermelon Growers

Fungicide

Total Acres Treated

Average Applications/yr

Bayleton (triademefon)

500

1

Bravo (chorothalonil)

285

2(1-3)

Dithane (mancozeb)

480

2(1-3)

Ridomil/Bravo (metalaxyl/ chorothalonil)

1875

1.8(1-3)

TennCop (copper salts of fatty & rosin acids)

675

1


2003 Estimated Use by State Specialist

Fungicide

Total Acres Treated

Average Applications/yr

Bravo (chorothalonil)

4000

2

Dithane (mancozeb)

1000

2

Topsin (thiophante-methyl)

1000

2

Quadris (azoxystrobin)

1000

1

Nova (myclobutanil)

500

1

Ridomil/Bravo (metalaxyl/ chorothalonil)

250

1


Fusarium Wilt
Fusarium niveum

Fusarium wilt is caused by a fungus that lives in the soil and penetrates the roots. Symptoms are a brown discoloration of the vascular system of roots and stems, followed by a wilting and death of the plant.

Control


Anthracnose
Colletotrichum orbiculare

Anthracnose attacks all above-ground parts of watermelon plants, can completely kill vines before the fruit mature, cause lesions on the fruit which ruins them in the field, or results in loss to decay in transit. The symptoms include irregular, brown to black, dry leaf spots, eventually causing the leaf to shrivel up and die. On the fruit, sunken, circular to irregular lesions occur from pinpoint size to one inch or more in diameter. Elongate stem and petiole lesions occur. Spores of the fungus are produced on lesions that may rapidly spread the infection following rainy weather. The fungus over winters in decaying vines and on seed from diseased fruit. It is the most important and destructive foliar disease in Oklahoma.

Controls


Alternaria Leaf Blight
Alternaria cucumerina

This disease causes leaf spots and defoliation. It over winters in infected plant debris in the soil and seed. It is a relatively minor disease.

Controls


Cercospora Leaf Spot
Cercospora citrullina

This disease causes small, circular, leaf spots that can cause defoliation of vines under severe disease pressure. Normally it is of minor importance.

Controls


Downy Mildew
Pseudoperonospora cubensis

This disease causes large brown blotches on leaves and rapidly defoliates vines. Stems and fruit are not affected. It is favored by cool, wet nights, and warm humid days. It is mainly important in late-season (fall) production.

Controls


Gummy Stem Blight
Didymella bryoniae

Gummy stem blight just attacks the leaves and stems of watermelon. This fungus also over winters in infected plant debris in the soil and seed. Minor importance in Oklahoma.

Controls


Bacterial Fruit Blotch
Acidovorax avenasubsp. citrulli

Causes brown spots on leaves that are of minor importance. Causes large water-soaked, greasy areas on upper part of fruit which renders fruit unmarketable. The disease is seed borne and survives in crop debris and in volunteer melons. Minor in Oklahoma.

Controls



Contacts

Charles Luper
Extension Associate
405-744-5531
luper@okstate.edu

Jim T. Criswell
Extension Pesticide Coordinator
405-744-5531
jtc@okstate.edu

Jonathan Edelson
Professor, Entomology
IPM, Vegetable Crops
580-889-7343
jedelson-okstate@lane-ag.org

John Damicone
Professor Plant Pathology
405-744-9962
jpd3898@okstate.edu

Lynn Brandenburger
Associate Professor, Food Crops
405-744-5404
lpb@okstate.edu

Pat Bolin
IPM Coordinator
405-744-9420
bolinp@okstate.edu



Reference

  1. Bolin and Brandenberg, 2001, Cucurbit Crop Production Manual, OCES

  2. 2002 OSU Extension Agents’ Handbook of Insect, Plant Disease, and Weed Control. Oklahoma Cooperative Extension Service Division of Agricultural Sciences and Natural Resources, E-832.

  3. Beste, E., D. Caron, G. Dively, K. Everts, E. Kee, S. Walker, J. Whalen, J. Windsor, T. Wooten, 1998. Watermelon Production Guide for Delaware and Maryland. Revised Draft.

  4. Chester, K.S. 1950. Nature and Prevention of Plant Diseases. Second Edition.

  5. Damicone, J.P., J.A. Duthie, B.D. Bruton, and J.E. Motes. 1994. Guide for Identification and Management of Diseases of Cucurbit Vegetable Crops. Oklahoma Cooperative Extension Service Division of Agricultural Sciences and Natural Resources, E-929.

  6. Drees. B.M. and J.A. Jackman. 1998. A Field Guide to Common Texas Insect.

  7. USDA/ERS Information Center. The U.S. Watermelon Industry.http://usda.mannlib.cornell.edu//data-sets/specialty/89029/

  8. Flint, M. 1990. Pests of the Garden and Small Farm. A Grower’s Guide to Using Less Pesticide. University of California Division of Agriculture and Natural Resources publication 3332.

  9. Oklahoma Agricultural Statistics 2001.

  10. Oklahoma State University Enterprise Budgets.

  11. Roberts, W., J. Motes, J. Edelson, J. Damicone, and J. Duthie. 1996. Watermelon Production. Oklahoma Cooperative Extension Service Division of Agricultural Sciences and Natural Resources, F-6236.

  12. Yepsen, R.B. 1976. The Encyclopedia of Natural Insect & Disease Control.

  13. Vegetables 2001 Summary. United States Department of Agriculture. National Agricultural Statistics Service. January 2002. http://usda.mannlib.cornell.edu/reports/nassr/fruit/pvg-bban/vgan0102.txt